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An Electronic Chalkboard for Classroom and Distance Teaching

1. else if pdf create color gt The session as lt A href pdf lect_col pdf target _TOP gt Portable Document Format lt A gt file n lt P gt lt P gt n else The session as lt A href pdf lect_bw pdf target _TOP gt Portable Document Format lt A gt file n lt P gt lt P gt n 2 J if echalk audio lt APPLET archive template archives code wwr wwrelient class width 1 height 1 name audio gt n if echalk audio sync alpha null lt PARAM name syncalpha gt value echalk audio sync alpha gt n lt PARAM name archivemode value audio gt n lt PARAM name loopmode value on gt n lt APPLET gt n if echalk video if echalk board lt APPLET archive template archives code console Console gt width 1 height 1 name console gt lt PARAM name title value echalk title gt lt PARAM name seconds value echalk recordingtime seconds gt if template skin src null lt PARAM name initfile value skin ini gt n y Please activate Java lt APPLET gt lt P gt lt DIV gt lt BODY gt lt HTML gt Listing 3 6 Default English template for archived replay Video and board Applet parts are omitted due to space constraints 56 CHAPTER 3 THE E CHALK APPLICATION string true is interpreted as true Bracketed sequences of values are inter preted as
2. FE stop _causc Close Figure 3 5 A memory usage monitor for the JVM realized as Launchable method A Launchable must provide a default constructor Note that there is no language mechanism in Java to enforce the presence of the default constructor or any other constructor signature in classes implementing an interface This can only be specified informally in the documentation It would have been possible to merge the init call with the constructor but demanding a default constructor for components by documentation is common practice like for example for Java Beans or for OSGI bundles in contrast to demanding other constructor signatures The launch command of the command line console dynamically loads the Launchable class given as the first argument instantiates it calls init on the instance with any further command line parameters as arguments and calls the launch method The command interpreter s thread is blocked until the launch method returns To avoid Launchables blocking the interpreter they have to be started in the background For this purpose any command can be started in a separate thread by using a trailing amp sign similar to Unix shell style commands started in the background The Launchable can then be stopped by using the deorbit command on it executing the method of the same name on the Launchable object An example of a Launchable supplied purely for development purposes is the memory usage m
3. Figure 1 10 A MANIC lecture on Unix network programming with RealVideo and RealAudio audio stream encoded in RealAudio experimentally also with RealVideo see Figure 1 10 The audio is encoded for low bandwidth quality requiring only a modem connection The system also comes with a connection to a MYSQL database for storing and searching courses with the access interface being built as PHP scripts for Apache Webservers The MANIAC 2 0 server is written in Perl the previous version numbered 1 5 was implemented in Java To create a MANIC course the author creates the HTML pages and or im ages externally To highlight text in the HTML pages the author manually adds a special MANIC tag into the document s HTML code Audio is encoded from DAT or videotape recordings The Timing Data Recorder TDR application creates program timing events for the presentations At the server the replay is controlled with CGI scripts At the client side a JavaScript enabled browser with cookies enabled and the RealAudio plug in installed is needed to view the course The viewer s navigation options include starting and stopping the re play jumping to the next or the previous slide and random access of slides via a table of contents 1 6 2 Cornell Lecture Browser The Cornell Lecture Browser MS99 17 which is also used by Berkeley as the BMRC Lecture Browser 5 shows slides with a synchronized RealAudio and RealVideo stream It uses JavaScri
4. Java Media Framework JMF http java sun com products java media jmf JavaView Homepage http www javaview de JLink for Mathematica by Wolfram Research Inc http www wolfram com solutions mathlink jlink 194 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 WEB REFERENCES Just In Time Lectures JITL http www jitl cs cmu edu Jython a pure Java Python implementation http www jython org KDE User Interface Guidelines http developer kde org documentation design ui Lecturnity http www lecturnity com Lemon Commodore 64 Museum http www lemon64 com museun LEO Deutsch Englisches W rterbuch PDA optimierte Version http pda leo org Libungif An uncompressed GIF library http sourceforge net projects libungif Lokando AG http www lokando com Lorenz Kaim Schule Kronach Berufsschule Unterrichtsbeispiel mit E Kreide http www bs kronach de Unterrichtsbeispiele gebr1 Lorenz Kaim Schule Kronach Rudolf Schirmer Berufsausbildung DBFH Mechatroniker http www bs kronach de DBFH projekt htm Lynx http lynx browser org MacroMedia Inc Authorware http www macromedia com software authorware MacroMedia Inc Director http www macromedia com software director MANIC Multimedia Asynchronous Networked Individualized Courseware by RIPPLES Research in Presentation Product
5. 22 22 20 8 4 2 Qualitative Study on E Chalk Courses 9 Outlook 10 Conclusion Bibliography Web References Appendix CONTENTS 167 169 191 199 Chapter 1 Introduction and Related Work Computers promise the fountains of utopia but only deliver a flood of information Langdon Winner Mythinformation Whole Earth Review Jan 1985 1 1 The E Learning Landscape The history of computer supported education is rooted in the early era of main frames In 1963 the PLATO system Woo94 Programmed Logic for Auto mated Teaching Operations was developed at University of Illinois It had custom built multimedia teaching terminal stations connected to the mainframe A proprietary language called TUTOR was created for authoring educational software More than 15 000 hours worth of instruction material were developed for PLATO Features like online chat and bulletin board notes were added in the early 1970s long before the Internet In 1976 Control Data Corporation CDC established PLATO IV as a commercial educational product with its successor still around 75 Recent years have witnessed considerable activity in the field of computer aided education With an access to the Internet being almost omnipresent people envision a new age of learning the learners will be free to learn when and where they want learning efficiencies will be heightened by a multimedia enriched learning experiences and training costs can be cut by re
6. JPEG format is incorrect The right term should be JFIF JPEG file interchange format whereas the specification can be found in ISO92 However the term JPEG format is used more commonly 13Some results from research on spatial attention suggest that it is actually possible to attend to two spatial locations simultaneously under certain circumstances HK98 BCP99 The model of assuming only a single locus may be simplistic but concerning its application in user interface design it is preferred for practical purposes 5 4 VIDEO AND BOARD IMAGE COMBINED 103 Figure 5 10 Screenshot of the experimental version for cutting out the lecturer The video is already shown over an board image but the lecturer s image is not yet correctly aligned with the board drawings strategy keeping track of the number of recurrences Those blocks with a high appearance count are likely to belong to the background others are considered foreground blocks i e the lecturer For details see JFRO4 This algorithm is currently refined by combining the initial strategy with other strategies for classifying between background and lecturer for example by looking at the color histograms of the blocks and by using edge detection filters Figure 5 10 shows an example result Note that these approaches do not yet take any advantage of information about the board content in the background which is available from the E Chalk board or alternativel
7. Whiteboard marker LCD Tablet gt Figure 1 13 Replay of a Tegrity recording about using Tegrity effects introduced by lossy video encodings a custom lossless codec the Tech Smith TSCC Codec was developed However it requires the remote viewer to install the codec for replay which is only available for Windows The presenta tions can be exported to standard video formats AVI QuickTime RealVideo with standard encodings but this re introduces the problems of hard to read contents Another commercial example is Tegrity 93 It captures the screen provides software for freehand annotation and records the audio and or video of the instructor A Java Applet player handles both live transmission and replay from an archive The player can be used by the students to add their annotations to the recording as freehand or as typed text Figure 1 13 shows a replay of a Tegrity recording in a Java enabled browser The Transparent TeleteachingTool 2502 TTT is a screen recording tool for teaching developed at Universit t Trier It uses the Virtual Network Computing RSF WH98 VNC tools for a networked screen capturing of the presentation computer at the TTT server The captured screen audio and an optional video signal are encoded by the server stored for replay and multicasted to remote viewers In synchronous access the audio signal is transmitted as uncompressed p law mono the video as M JPEG encoded
8. arrays have to be checked for visibility With the Forms of a single page being already ordered all the relevant Forms can be retrieved in the correct order from the page arrays in linear time Elements which are shown only temporarily on the board like image placing frames and text input cursors are not painted to the offscreen buffer Instead they are painted directly to the screen using XOR paint and removed by re painting with another XOR paint For the board client an instance of the echalk shared DrawPanel class is the component handling the actual display of the board content implementing double buffering and processing board events into new Forms or changes to ex isting ones The subclass echalk board gui ActiveDrawPanel is used for the server side board The ActiveDrawPanel is capable of processing user inputs to create board events To allow adding Applets to the DrawPanel see Section 4 10 the DrawPanel class inherits from the container java awt Panel 4 2 Drawing Lines The board feature used most is the plain drawing feature A drawing action is achieved by a mouse drag like motion with a pointing device The board receives the points of the drag movement and connects these points to a stroke in the current drawing color and drawing width Eraser actions are handled like drawings in the background color A stroke to be painted is stored in a echalk util form StrokeForm object A StrokeForm stores the list of its vertex p
9. Aufgaben Galerie Figure 7 8 A snapshot from 23 a slide show with audio and control panel created by Schule des Sehens 86 an e learning project on art The different lesson slides illustrate different details of the art work explained self the frame that contains the slide show Applet parent the Applet s parent frame _top the top level frame of the Applet s window and _blank a new unnamed top level window If a named frame is used and a frame of that name does not already exist a new top level window with the specified name is created and the document is shown there If the parameter is omitted the default target is used initially set to the target name slideframe The showurl commands are executed in the order of their timestamp values When two commands use the same timestamp they may be executed in any order The other type of entry is used to set the default target for following showurl lines Its syntax is defaulttarget utarget where target is the new target If it is omitted the default target is set to the frame with the name slideframe creating it in a new top level window if it does not yet exist The data file for the slide show can be created either directly with a text editor or more comfortably with the Exymen editor see Section 6 13 Jumping to a timestamp to is realized as displaying the last document to be shown in the interval 0 to The parameter recognized by the slide show Ap
10. CSCW pages 285 294 Seattle WA USA November 1998 ACM press Thomas P Moran and William van Melle Tivoli Integrating structured domain objects into a freeform whiteboard environment demonstration In Proceedings of the Conference on Human Fac tors in Computing Systems CHI The Hague The Netherlands April 2000 ACM press Demonstrations video physical and shared spaces Thomas P Moran William van Melle and Patrick Chiu Spatial interpretation of domain objects integrated into a freeform elec tronic whiteboard In Proceedings of the eleventh annual ACM symposium on User interface software and technology UIST pages 175 184 San Francisco CA USA November 1998 ACM press Thomas P Moran William van Melle and Patrick Chiu Tai lorable domain objects as meeting tools for an electronic white board In Proceedings of the ACM conference on Computer sup ported cooperative work CSCW pages 295 304 Seattle WA USA November 1998 ACM press Victor S Miller and Mark N Wegman United States Patent No 4 814 746 Data compression method 1983 International Business Machines Corporation filed on June 1 1983 Brad A Myers The pebbles project using PCs and hand held computers together In Proceedings of the Conference on Human Factors in Computing Systems CHI pages 14 15 The Hague The Netherlands April 2000 ACM press Brad A Myers Using hand held devices and PCs together Com munications of the
11. aiiin jpg E lazione New StON Ing 5 Echo Demo Chalklet vertical Esa Tic Tac Toe remote El Echalk Create Chalklet Bookmark Classpath URL http www online lectures org chalkletsil Choose dh Search Class Name hples chalklets logierec LogieChalkletKit Echalk Chalklet Properties Logicrecognition Masa Ti Delete stg math Jaa mural Default octop Cut Thumbnail penal T copy Raul snel b Setup for a plugin which recognizes and simulates handwritten logical circuits lionfig lt 3 Choose File Stg 0 jpg lions Import Directory Sti fejpo Chalklet Logicrecognition Classpath http wnr online lectures org chalklets logic jar Class de echalk xsamples chalklets logicrec LogicChalkletKit sketch of echalk system file ybdechalk idea gif table coral file gbetablecoral jpg tiger file gfutiger gif file ghdweatherjpg Feedback Config File Saved Gates Directory Diagram Draw a diagram during simulation vi Diagram Cancel Figure 2 5 Left The bookmark editor for image bookmarks Right The book mark editor for chalklets in the process of defining a new entry The properties dialog provides a tabbed page for each of the four expected build parameters defining formal name prompt for query on the board and HTTP send method POST or GET The bookmark setup for chalklets
12. if no control panel is present the client will have to start automatically or it will pause indeterminately The default value for this entry is true for live transmissions when no control panel is present and false for archived replay when the control panel Applet is used for control embedded Setting this parameter to true causes the client board to use the Applet area in the HTML page rather than opening its own frame The default value is false This parameter was introduced due to user requests In a distance teach ing project at Universitat Regensburg users wanted to combine video and audio streams in Real format 79 with a timed display of Web pages trig gered with SMIL W3C98 W3C01 Some of the pages were to contain short board recordings With their remote viewer already operating both a RealPlayer window and a Web browser they wanted to avoid another window for the user to operate autoclose A client is notified of the end of a live transmission by a terminate event see Section 4 10 2 By default or when autoclose is set to false it opens a message dialog to notify the user This is especially important for transmissions without audio signal as the remote viewer would have difficulty in distinguishing between a transmission that has ended one that stalls or one where the teacher simply pauses for a while Note that for replayed lectures this is usually not needed due to the presence of the control panel Appl
13. s voice This information is stored for the later recording phase The wizard assists users in assessing the quality of the audio equipment and makes them aware of the equipment s influence on the recording e During recording filters hardware monitors and automatic gain con trol work with the information collected by the expert system Clas sic recording studio equipment like graphical equalizers noise gates and compressors are simulated and automatically operated 5 2 3 Setup Before lectures are recorded the user creates a so called audio profile It repre sents a fingerprint of the interplay of sound card equipment and speaker The profile is recorded using a multi step wizard that guides the user through sev eral steps see Figure 5 2 This setup takes about three minutes and has to be done once per speaker and sound equipment Each speaker uses their own audio profile for all recordings The setup screen asks to assemble the hardware as it is to be used in the lecture recording The wizard detects the sound card and its mixing capabilities see Figure 5 3 Using the operating system s mixer API the sound card s input ports are scanned to find plugged in recording devices This is done by briefly reading from each port with gain set to maximum while all other input lines are muted The line with the highest noise level is assumed to be the input source If noise level differences are below a certain threshold the user is re
14. 43 E Chalk relies on its own implementation of the Bre senham circle drawing algorithm Bre77 68 CHAPTER 4 BOARD SERVER New New New Undo Undo Ta Form l undone Form insertion index Figure 4 3 An example of handling a sequence undos redos and Form object creations The example sequence is taken from the UndoManager example in LEW 02 is delegated to the Applet s paint method When the Applet is added to the board it is registered as a java awt Component to the DrawPanel For this reasons the DrawPanel inherits from java awt Container see Section 4 1 Whenever the AppletForm s absolute position changes due to a scroll event the Applet s setBounds java awt Rectangle method is used to redefine its area For description of logging AWT events of Applets for replay purposes see Section 4 10 1 4 5 Undo Redo and Clear All To realize Undo and Redo actions the board stores all Form events sequentially in an array and keeps an index to the next point of insertion into the array like a stack 4 An undo command decreases the index by one a redo reinserts an undone element by increasing the index When a new Form is added redo of previously undone elements becomes unavailable See Figure 4 3 for illustration A Clear All command is rarely used It simply removes all elements from the Form array 4 6 Custom GUI elements The b
15. 6 1 1 PDF Structure A PDF is organized as a tree of objects The main element to organize the document is the PageTree A PageTree contains Pages objects which list other Pages and or Page objects A Page has a list of objects specifying the actual content of the page All PDF objects are numbered and used in other objects by this reference The trailer of a PDF file contains a table that maps object references to their byte address in the file See Ado03 for details The PDF converter outputs a flat hierarchy of PDF objects that keeps the number of objects low This makes the resulting PDF smaller as the overhead for defining objects is reduced It also speeds up the process of loading and rendering a PDF Only a single Pages list is used and each Page has only a single content object The content part consists of basic PDF drawing commands like line strokes text drawings included images and changes to the current graphic state like setting stroke width and paint color The Portable Document Format allows to compress content data with a range of compression filters including run length encoding RLE LZW ZL78 Wel84 and flate compression ZL77 DG96 Deu96 The PDF converter program uses flate compression on the page con tent data except for content objects where this does not save storage space This is true only for very small content objects where the compression specifi 6There may be a few extra objects for images an
16. A color can be reserved for input to the recognition module in the setup Writing a special tick symbol marks the end of a handwriting request The recognized string is sent to the connected computer algebra system or to a simple built in calcu lator if no algebra system is set up and the result is added to the board See Figure 2 14 for an example Chalklets Chalklet are a kind of interactive animations designed for the E Chalk board On creation a chalklet is assigned a rectangular section of the board to operate on The chalklet then receives what the user draws into that area and may itself draw strokes in the chalklet s area Chalklets implemented so far include a game of Tic Tac Toe a logic circuits simulator working hand drawn circuits definitions and a python interpreter for handwritten programs See 6 12 for example chalklets When a chalklet bookmark is selected one has to define the chalklet s area on the board A chalklet defines its minimum area When a click is used for positioning the chalklet instance receives this minimum area Alternatively the area can be dragged to a bigger rectangle See Figure 2 11 Chalklet s areas are allowed to overlap User drawn strokes in the intersec tion of the areas are sent to all the listening chalklets A chalklet scrolled out of the visible area is deactivated 26This prevents chalklets from changing the board image without the user being able to notice 2 5 R
17. FP04 SOPA is built on top of the OSGi 71 open services gateway initiative standard a mechanism originally coming from the field of ubiquitous computing It specifies 1This task requires a developer to overwrite up to ten methods for building a wrapper to a streaming service one wants to integrate 93 94 CHAPTER 5 AUDIO AND VIDEO SERVERS GainControl vun tan Audiograbber TCPServerTarget Figure 5 1 A simple audio streaming server graph how to load update and delete software components from the Internet while a system is running OSG02 HC04a SOPA uses the Oscar OSGi implementa tion HC04b 70 5 1 2 Audio Codecs WWR2 Codecs Current browsers often only have a Java environment of Java version 1 1 pre installed In such environments Java Applets cannot play back sound with a sampling frequency higher than 8999 Hz 38 Hence the basic input format chosen for WWR2 was 8kHz 8bit w law mono as defined in Int88 the format used for digital telephone lines It requires a connection speed of 64 kbps Several codecs for different bandwidth CPU speeds and audio quality levels were integrated into WWR2 by modifying older compression standards WWR2 contains a simple and fast 50 kbps codec which uses no compression but the Java s built in gzip algorithm To achieve better compression WWR2 also contains the 4 bit version of the law codec which is adapted from Int88 This co
18. For the board the handling is slightly more complex due to the event based representation of the board format In the case of a late connect it has to load all past events to build up the current board image 27 A further extension can be the possibility to resume stopped macros and an interactive control of the replay speed 8The macro recorder is described in Section 6 9 29 A tool to generate E Chalk macros for animating algorithms is described in Esp04 see Section 6 12 2 30Due to the security instructions on Applets the client Applets can only connect to the Web server they come from For this reason the E Chalk main application must run on the Web server in live transmissions An alternative would be to run a proxy on the Web server which hands just hands the data over 44 CHAPTER 2 USER INTERFACE Porammiden me Gamps Laplace Gli ws Be N Dilun i Zi Haske Interpolckon Figure 2 16 Left An E Chalk lecture seen in the board Applet Right The corresponding PDF page The board client allows vertical scrolling by the remote user enabling the user to look at older board content already scrolled away This can be done by using a scrollbar featured by the board client or by dragging Horizontal dragging is also possible when the width of the remote client board is smaller than the board at the server side This is usually the case when the full board does not fit on the receiving computer
19. and Steven A Wolfman Speech ink and slides The interaction of content channels In Proceedings of the Twelfth ACM International Conference on Multimedia 2004 pages 796 803 New York NY USA October 2004 ACM press Richard Anderson Crystal Hoyer Craig Prince Jonathan Su Fred Videon and Steven A Wolfman A study of digital ink in lecture presentation In Proceedings of the conference on Hu man factors in computing systems CHI pages 567 574 Vienna Austria April 2004 ACM press 169 170 And04 App87 App92 App93 App0la App01b Baa88 BAT99 BBJ 98 BBW04 BCD 98 BCP99 BG96 BIBLIOGRAPHY Richard Anderson Beyond PowerPoint Building a new classroom presenter Syllabus Magazine pages 31 33 June 2004 Apple Computer Inc Apple Human Interface Guidelines The Apple Desktop Interface Addison Wesley 1987 Apple Computer Inc Macintosh Human Interface Guidelines Addison Wesley 1992 Apple Computer Inc Cupertino CA USA Newton Apple Mes sagePad Handbook 1993 Apple Computer Inc Inside Mac OS X Aqua Human Interface Guidelines October 2001 Apple Computer Inc Inside QuickTime QuickTime File Format March 2001 Specification of the QuickTime file format Bernard J Baars A Cognitive Theory of Consciousness Cam bridge University Press Cambridge UK 1988 Jason A Brotherton Gregory D Abowd and Khai N Truong Supporting capture and access
20. audio video are initialized for recording As the setup may take a few moments a dialog with an animated indeterminate progress bar is shown if it takes more than half a second During the recording stream data are written continuously to the disk This avoids potentially long saving times at the end of a lecture and minimizes data loss in case of an abnormal program termination When the recorded streams include the board stream the recording is ended by exiting from the board interface Otherwise the system displays an informa tion dialog with an indeterminate progress bar animation and a button to stop the recording see Figure 2 9 for an example After the recording a recorded board stream is converted to a PDF tran script if the option was chosen in the setup Again if the process takes longer than half a second dialogs with progress bars are shown 17The paper formats supported in the current implementation are DIN AO to A6 letter half letter legal note and ledger 18 specially appending to a long previous session may cause the board initialization take some time because the board must load the complete data of the old session 38 CHAPTER 2 USER INTERFACE El Echalk ER Bl Echalk FE General A Board lt Audio Sviieo El Live Server amp por 2 General A Board Audio El video LiveServer amp PDF Max Connections hE 3 Paper Size DINA4 zj Parts Maximum Number of Live Connections Se
21. drag handles are part of the board When the instructor starts a drag action at one of these handles he or she moves the board content up or down like pulling a blackboard up or down The mouse pointer is shown as a hand icon during dragging and when it is above the drag handle see Figure 2 11 Images and Applets The system allows the user to paste images from local hard drives or from the Internet Pressing the add image button a dialog displays the image bookmarks with titles and thumbnail icons see Figure 2 10 The user can pick one of the bookmarks or type in an image URL or select an image file with a file dialog from a local disk The file dialog applies a file filter to show only the supported file formats GIF and JPEG When the user has selected an image the loading process starts This process may take a noticeable time as remote image locations are allowed If it should take more than half a second a progress dialog with a cancel button is opened enabling the user to abort lengthy loading actions Except for the cancel 20PNG images can also be handled by the server software However in the default setup their usage is disabled because the PNG format is not guaranteed to be displayable in remote E Chalk clients The client relies on the Java decoding of images and Java versions before 1 3 lack PNG support in some browsers 21 The same approach is taken for other types of resources that can be added to the board
22. equal lt lt gt gt and the boolean operators amp amp and or and not Compar ison operators work with lexical string order Possible return values of boolean operators are the strings true and false As boolean operand only the 20The VCR control Applet is described in Section 7 1 21For example the default pages use the lecture title as page title 2The syntax could easily be extended by additional statements like loops or arithmetic operators to make the template syntax computationally complete Also allowing an operator for indirect addressing might be introduced then For the templates produced here the power of the provided statement is enough and the simple syntax makes the template definition less error prone When targeting at a full fledged programming language it would make more sense to use a standard script language like Perl or Python 3 7 HTML TEMPLATES 55 lt HTML gt lt HEAD gt lt TITLE gt E Chalk echalk title lt TITLE gt lt META name author content user name gt lt META name date content date gt lt HEAD gt lt BODY bgcolor 000000 text FFFFFF gt lt DIV align center gt lt H1 gt echalk title lt H1 gt lt P gt if echalk pdf if pdf create both The session as PDF files gt lt A href pdf lect_col pdf target _TOP gt color lt A gt and lt A href pdf lect_bw pdf target _TOP gt b w lt A gt n lt P gt lt P gt n
23. handles the Applet s parameter specific setup and controls the replay An instance of the inner thread class Client EventReaderThread concurrently reads all the events for live transmissions that is done from a server socket for a recorded lecture directly from the event file The event reading thread submits the threads to the echalk client EventScheduler which handles the timed delivery of events to the DrawPanel For a recorded lecture including an audio stream a thread EventScheduler AudioSyncThread is started adjusting the local board time at regular intervals every five seconds to match the audio client s time and thus preventing a slowly accumulating synchronization offset 7 2 2 VCR Operations While the audio and video stream need only the stream data of the current point of time to the event based nature of the board means the board needs to examine all events in the interval 0 to to construct the board view for to When the board has to jump from a time offset to to an offset tp At in the future 5See Section 4 1 6See Section 4 11 7See Section 4 10 7 2 BOARD CLIENT 133 com amp A RADA ES E ooge 9 oome 2222 00 MED 000065 600 Figure 7 4 Two example skin graphics left the default skin and right an OS X Aqua style one Transparent image parts are shown in white the scheduler has to try to submit all missing events events with timestamps in to to At immediately This
24. like CGI calls or requests for mathematical computations 40 CHAPTER 2 USER INTERFACE Figure 2 11 Top row left to right Drawing tool mouse pointer eraser tool pointer pointers for tools of big sizes the hand pointer over the top drag han dle placement of an image or Applet positioning a chalklet and dragging the chalklet area bigger with currently selected area painted semi transparent over an existing board drawing At bottom Positioning a macro option the board does not accept any interaction during the loading process When the image data have arrived the user is expected to place the image on the board The mouse pointer changes to a cross hair and the bounding rectangle of the image is attached see Figure 2 11 The image s upper left position is set by a mouse click Once put on the board it can be regularly painted with board drawings letting the instructor annotate the image Another button provides the same functionality for adding Applets to the board content Their URLs reference HTML pages with embedded Applets When the selected page contains more than one Applet all of them have to be positioned by the user Like in a Java enabled browser the board then executes the Applets which can be interacted with regularly see Figure 2 12 Unlike the images one cannot draw on the Applets with the board tools because all mouse events on the Applet screen areas are consumed by the Applets Typing Text Another b
25. lt cmd gt cat lt file gt clear close cset lt key gt lt value gt cunset lt key gt deorbit lt no gt destroy lt no gt echo lt string gt exec lt command gt lt arg gt finalize free gc help history lt n gt hsave lt file gt hsetsize lt n gt hsource lt file gt iconify info interrupt lt no gt jobs launch lt class gt lt arg gt ls alFQRkhfStXr lt file gt mkdir v lt dir gt ps quit resume lt no gt rmdir vp lt dir gt save lt file gt seppuko set lt key gt lt value gt setpriority lt no gt lt pri gt source lt file gt sset lt key gt lt value gt suspend lt no gt ts tstop lt no gt unalias lt alias gt unset lt key gt version comment no effect list set command aliases print out files clear console disposes console list set config properties remove config property request termination of job lt no gt destroy thread lt no gt output strings execute native system command request of pending finalizations show memory statistics request garbage collection show this help print console history entries dumps history to file sets command history length load commands into history iconify console show echalk copyright info interrupt thread lt no gt list jobs launchables started in bg with amp starts a launchable list directory contents m
26. mats to any other of the audio formats listed above Another Exymen plug in available with the standard distribution allows to convert Microsoft PowerPoint Presentations exported as HTML pages to the E Chalk slide show format and to be edited with the above mentioned plug in for the slide show format An example of editing an E Chalk lecture of a slide show including an audio stream is shown in Figure 6 19 E Chalk Board Plug in While editing the multimedia data for audio video and slide shows is pretty straightforward editing the board content poses a few challenges The board stream represents the development of the board content as a sequence of timed events but events are not independent from previous events For example a redo event is only allowed after an undo event and a line drawing can only happen on the visible portion of the board meaning it is dependent on the offset generated by the antecedent scroll event These structural and spatial dependencies are classified in Fri02a It de scribes how the plug in manages to constantly maintain the dependencies within a Chunk for all editing operations The main idea behind preserving the non spatial dependencies is to organize the board chunks content data into atomic 6 13 POST PRODUCTION WITH EXYMEN 127 A E Chalk Boardeditor zweierkomp 00 00 00 16 24 25 Position Length Dira Figure 6 20 Removing a vertical board interval with the board MediaEditor F
27. men Kosten f r die Produktion von E Learning Materialien Daneben profitiert der Ansatz von den bereits vorhandenen didaktischen F higkeiten der Lehren den in der klassischen Unterrichtsform mit der Kreidetafel Die Fernlehrnenden k nnen die Aufzeichnung in einem Java f higem Brows er abspielen ohne das hierzu die Installation von speziellen Programmen zum Empfang n tig ist Die bertragung kann live empfangen werden oder zu einem sp teren Zeitpunkt abgespielt werden etwa zum Zwecke der Nachbereitung Die Arbeit beschreibt Entwurfsprinzipien und Architektur des Systems eben so wie die Erfahrungen aus dem praktischen Einsatz Lebenslauf 1990 1999 Studium der Mathematik und Informatik an der Freien Uni versit t Berlin 1993 1995 Forschungstutor bei Prof Dr Helmut Alt im Bereich Punkt mustererkennung zur Satellitensteuerung 17 11 1998 Abgabe der Diplomarbeit Beschriftung von Linienz gen 29 04 1999 Diplom Mathematik 18 10 1999 Diplom Informatik 1 5 30 11 1999 Wissenschaftlicher Berater des Sender Freies Berlin im EU Projekt Estima Ratio Seit 1 12 1999 Wissenschaftlicher Mitarbeiter in der Arbeitsgruppe Multime dia am Institut f r Informatik der Freien Universit t Berlin 199 200 APPENDIX Selbstst ndigkeitserkl rung zur Dissertation Ich versichere hiermit dass ich die Dissertation selbst ndig verfasst habe und dass ich keine anderen als die in der Arbeit genannten Hilfsmittel benutzt habe Lars Knipping
28. missions round trip delay would be twice that The WWR2 implementation used a delay of 12 700 ms while in the new WWR3 version the buffer time was reduced to 4 763 ms The values are results of experiments to find a good trade off between interruption free transmission and small delay The smaller delay in the newer version reflects improvements in the Internet s quality of service achieved in the last five years 7 3 1 VCR Operations The audio data stream consists of packets that contain audio data for a fixed duration 4 763 ms The storage size of the packets varies and is stored in the packet s header To fast forward WWR2 recordings the client runs through the packet s headers until it skipped enough packets Even worse for jumping backwards in time the client has to read the audio data from the beginning until it reaches the desired packet For WWR3 data this method is used only as fallback Nearly all Web servers today support HTTP requests for random access reads FGM 97 FGM 99 The WWR3 server stores both the encoded audio data and an index file which contains the sizes of the audio packets With the index information the audio client can jump directly to the right packet dramatically speeding up the oper ation The old method is used only if the index file cannot be accessed or if the Web server does not support byte range requests 7 3 2 Parameters Parameters recognized by the audio client Applet include
29. 0 http developer gnome org projects gup hig WEB REFERENCES 193 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 Evan Golub The BIRD Beacon Identified Realtime Display Note taking System http www cs umd edu egolub AVIAN BIRD GTCO whiteboards http www gtcocalcomp com Hades Hamburg Design System http tech www informatik uni hamburg de applet hades html1 Heise Online Microsofts Internet Explorer verliert gegentiber Mozilla Firefox Anteile http www heise de newsticker meldung 51152 Himmel5 The Art Show http www himmel5 de Hitachi Software http www hitachi soft com iLectures http ilectures uwa edu au imc Information Multimedia Communication Advanced Learning Solutions http www im c de Java Platform 1 1 API and Documentation http java sun com products archive jdk 1 1 Java 1 4 2 API Documentation Class java text MessageFormat http java sun com j2se 1 4 2 docs api java text MessageFormat html Java 1 4 2 API Documentation Class java util Properties http java sun com j2se 1 4 2 docs api java util Properties html Java 1 4 2 API Documentation Class java util ResourceBundle http java sun com j2se 1 4 2 docs api java util ResourceBundle html Java API Documentation http java sun com reference api Java Bug Database http developer java sun com developer bugParade
30. 12 70039 11 4 2975178 485 2 eigenvalues 87 103 18 52897 8 5 2244007 362 0 eigenvalues 111 102 51 77080 12 5 3292172 533 5 optics 96 94 03 47334 8 4 1985525 351 9 thermodynamics I 97 91 57 42202 7 6 1829194 331 6 disc Fourier transformation 6 89 24 88233 16 5 3832611 715 8 polynomial interpolation 7 79 38 78190 16 4 3362383 703 7 surface integrals 98 99 11 90992 15 3 3978159 668 5 stokes theorem 99 89 23 89913 16 8 3919085 732 1 Table 4 2 Recorded E Chalk sessions from courses at Freie Universit t Berlin and at Technische Universit t Berlin Capsules denote short modules recorded without listeners the other entries are produced as full lectures held with E Chalk Horizontal lines separate recordings from different authors it makes more sense to implement a simple custom format that is both better readable for humans and simpler to parse by programs Also using XML would introduce a structuring overhead that would noticeably increase the size of the representation 4 11 2 Structure The first five lines form the header of the file starting with the magic file marker eci in the first line followed by width and height of the board in decimal ASCII representation a line containing the lecture s title and finally the background color All colors in the event file are stored as hexadecimal a RGB values even though a values are not yet sup
31. 2 2 22 on En 83 4 11 Event Storage sro a ale Bi Bee nern 85 AAT Encoding g 4 rau ner 2a SE a AE Poe 85 4 11 22 Structure ski ee See ars AA E e S 87 4 12 Live Server s ta of ated Sd ae ee a ee 91 Audio and Video Servers 93 5 1 The WWR Audio Server 0 002000000005 93 5 1 1 Server Architecture 0 00 000 93 5 1 2 A dio Codecs saa oae aie 2 it LI Ee aD 94 5 2 Smart Audio Recording 2 2 2222 onen 95 5 2 1 Sources of Interference onen 95 5 2 2 Enhancing Recordings o 96 CONTENTS 522 3 Setup 4 64 Sad Hed De Ue A AR 5 2 4 During Recording 0 0 5 3 The WWV Video Server o 5 4 Video and Board Image Combined o oo 6 Tools Converters Add ons 6 1 Export to PORE esaa a e a a dos pb PDE Structure 2 22 rs e ta de 6 12 mages 22 4 gt 24 444 wm ne aan area eee A 6 1 3 Color Conversions 2 2 2 22mm 6 2 Export for Replay in Windows Media Player 6 3 Export to QuickTime and AVI Video 6 4 Creating Board Snapshots o o 6 5 Audio Format Updater o 6 6 Repairing Damaged Recordings o nn 6 7 Import of PowerPoint Presentations 6 8 Keywords from Handwriting Recognition 6 9 Macro Recorder nn 6 10 Automated DB or LMS Storage o 6 11 Handwriting Synthesis o e e
32. 3072768 pixels realized as a combination of three Smart rear projectors each of the three segments using its own computer Its software supports video conferencing and sharing content material between the local and the remote meeting sites As described in Gei98 it also supports gestures for shuffling display objects around throw them to office users standing at the opposite side of the wall take objects and put them back at another location exploring new forms of interaction with electronic boards The FLUIDUM 27 flexible user interfaces for distributed ubiquitous ma chinery lab research at Universitat des Saarlandes is of a similar vein with the goal of developing techniques and metaphors for differently scaled Ubiqui tous Computing scenarios like interactive desks rooms and buildings Among others the wipe gesture is researched as an interaction technique 1 5 6 IRoom I Workspace The Stanford I Workspace WJF02 is another project on interactive workspaces Their Room interactive room is equipped with a display enhanced table and a high resolution back projection wall the Stanford Interactive Mural measuring 6x3 5 feet with a 64 dpi resolution and realized with a 4x3 array of projectors 1 5 PEN BASED OFFICE AND CSCW TOOLS 15 NotePals landay Note Browser Change Password Logout View as list Project Author Date Type Fogg El fan El An El far Filter Sort by Project Author Date Typ
33. 3See handwriting synthesis description in Section 6 11 165 At MIT another framework for sketch recognition was developed Sez01 HD04 including a description language for drawings called LADDER HD03 Applications realized with the framework include Tahuti HD02 for creating UML diagrams by sketches and ASSIST ADO1 a sketch based CAD system Another example of a stroke based interface is Flatland MIEL99 MIELOO described in Section 1 5 4 Improvements to Replay In addition to the standard VCR operations provided for replay it would be useful to provide a kind of spatial control for the board stream A scaled down version of the final board content could well be provided The learner should then be able to jump to the time offset at which selected board content was created This would enable users to navigate in the lecture to a subject without having to search along the time line Small screen rendering techniques should be applied to enable replay on platforms that offer only resolutions lower than the one used for the recorded board see Section 8 1 3 Possible approaches include automatic scrolling to cur rently changed content and fish eye view techniques This would enable replay on hand held devices as well as recording with high resolution hardware 166 CHAPTER 9 OUTLOOK Chapter 10 Conclusion Lectures said McCrimmon are our most flexible art form Any idea however slight can be expanded to fill fift
34. 6 12 Example Chalklets o o e 6 12 1 EchoChalklet and TicTacToe 6 12 2 Animated Algorithms 6 12 3 Simulation of Neural Networks 6 12 4 Simulation of Logic Circuits o 6 12 5 Python Interpreter o o e 6 13 Post production with Exymen o o 6 13 1 Plug in Management 6 13 2 Data Structure lt o an BEE EEE A 6 13 3 Editable Formats 2 2 2222 nn 7 Client Applets 7 1 Client Control Panel and Masi Interface 2 Board Client ra o 2 a A an een 7 2 1 Event H ndling nous bb ead anne 1 232 VER Operations n h na A ta a 12 37 SCLOUIMG a Ah A a ae 7 2 4 Handling Applets o 7 2 5 Board Parameters 0 m nn nn 1 3 AUd1O Client 3 2 0 2 AE AS I a Ae ee a 1 3 1 YVGR Operations se ea ua ss eS eee ee Se da 1 332 Parameters anne ine ee ge a G CA Vid o Client nu dela EA Dr re 8 7 5 Slide Show 8 Experiences and Evaluation 831 Case Studies n Tu u r E ae 8 1 1 Hardware Setup in the Lecture Room 8 1 2 Uses for Remote Access o o 8 1 3 Replay on Hand held Devices vii 97 99 100 102 105 viii 8 2 Eval ations se e een ee po anne eS 8 3 Studies During Summer Term 2003 8 4 Studies During Winter Term 2003 04 8 4 1 Comparative Studies 2
35. Alison Young and Tony Clear editors Winds of Changing in the Sea of Learning Proceedings of the nine teenth Annual Conference of the Australian Society for Comput ers in Tertiary Education ASCILITE pages 749 758 Auckland New Zealand December 2002 UNITEC Institute of Technology Auckland New Zealand Web References 10 11 12 AOF Authoring On the Fly http ad informatik uni freiburg de aof AudioGraph Homepage http carol science uva nl jesshope audiograph audiographhomepa html AutoAuditorium http www autoauditorium com BlackBoard http www blackboard com BMRC Lecture Browser The Berkley Multimedia Research Center University of California http bmrc berkeley edu projects 1b Matthias Bollh fer Numerik I Diskrete Fouriertransformation E Chalk recording summer term 2003 http www moses tu berlin de Mathematik Numerik1 SS_2003 NMI Echalk num_bolle_2003 06 19 Matthias Bollh fer Numerik I Polynominterpolation E Chalk recording summer term 2003 http www moses tu berlin de Mathematik Numerik1 SS_2003 NMI Echalk num_bolle_2003 06 18 Camtasia http www techsmith de products studio Centra Symposium http www centra com products CiDS Computer in die Schulen http www cids de Cinderella The Interactive Geometry Software Cinderella http www cinderella de Georg Classen Elektronische Kreide als Hilfsmittel f r behinderte
36. Applets on the board due to its restriction to the server side it would be worth to integrate it for the use of chalklets as these are only running on the server side while the board client only handles their stroke events 4 11 EVENT STORAGE 85 clicks on a moving target displayed in an Applet at the server board and the target moves with a different speed on the client board the mouse event might miss the target in the replay Even worse the board has no appropriate way to handle time dependent states in replay for navigation in time leading to inconsistencies when the user uses fast forward or rewind on the replay e Applets reading from the network When the Applet reads from a network connection the data read will usually not be available for the replay For example the lecturer might use a chat client Applet that reads the communication data from a chat server The chat server must run on the same server the chat Applet came from as the security model of Java does not allow Applets to connect to different locations During replay the chat Applet can only connect to the side where the board replay came from and usually there will be no appropriate chat server e User AWT events generated on client side The remote user cannot be prevented from interacting with the Applet in the replay By having Applets receive both kinds of AWT events the lecturer s recorded events and the input at the client side the Applet may easil
37. Berlin den 15 11 2004
38. Common operations should be quick and easy while uncommon things should be still possible Avoiding Modes Mode errors occur when the user misclassifies a tool s status resulting in inap propriate actions for example when one tries to fast forward on a VCR during record mode or when one turns the car key when the engine is already running The notion of mode errors was first defined in Nor81 Several types of modes are distinguished Spatial modes dependent on loca tion of input tool like click on which element The locus of attention is usually at mode determining object and therefore these types of modes are not prone to errors Quasi modes depend on the state of the system and use a kinesthetic feedback to the user Examples are pressing down the shift key mouse drag ging with mouse button down and opening popup menus while holding the mouse button down Experiments have shown that these modes are also not prone to user mistakes SKB92 Temporal modes depend on the internal state of the system Temporal modes increase the cognitive load of users and are T An objection to this might be that it uses disk space even if the session is only meant for drawing a quick illustration as E Chalk is sometimes used in brainstorming sessions Also first time users were sometimes irritated because they were already trained by numerous applications to always explicitly save their documents However in this case the value of adhering
39. Dozenten December 2003 http www fu berlin de service behinderung aktuell ekreide html 191 192 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 WEB REFERENCES Classroom Presenter http www cs washington edu education dl presenter Classroom2000 http www gatech edu fce eclass ClickTeam Company Multimedia Fusion http www clickteam com English multimedia_fusion htm ConferenceXP http www conferencexp net Cornell Lecture Browser Multimedia Research Group University of Cornell http www cs cornell edu zeno Deutsches Museum http www deutsches museun de DigiWB project aGNU Linux driver for Mimio E Beam and IntelliBoard http mimio spline de DyKnow Dynamic Knowledge Transfer LLC http www dyknow com eBeam Electronics for Imaging http www e beam com E Chalk http www echalk de Englische Kunst des 18 Jahrhunderts William Hoghart Teil 1 Mirror Production by Werner Busch and Maximilian Benker http kazan inf fu berlin de echalk lectures arthist Esmertec AG http www esmertec com Exymen EXtend Your Media Editor Now http www exymen org Exymen at SourceForge http exymen sourceforge net FLUIDUM FLexible User Interfaces for Distributed Ubiquitous Machinery http www fluidum org Ghostscript http www ghostscript com GNOME Human Interface Guidelines 2
40. Figure 2 3 Left Setup dialog for General settings Tabs for Video and Live Server are deactivated as their corresponding checkboxes are not selected Right E Chalk text editor started for the expert mode configuration 2 4 1 Setup Dialog The E Chalk setup dialog allows to change the user recordings setting All these settings are stored persistently in a human readable format The different settings are grouped into tabbed pages with the General settings selected at startup as shown in Figure 2 3 Users can set the lecture s title and the path of the directory to store the recording to They may select which types of material to store board stream audio stream video stream PDF from board content and whether the lecture should be transmitted live In most sessions the settings on the following pages can remain unchanged The dialog serves as a graphical interface to conveniently change all param eters commonly used Some configuration entries however are only interesting to expert users To avoid these settings cluttering the dialog they are to be changed directly in the file where they are stored To this end a button labeled Expert Mode is part of the general setup page see Figure 2 3 It is used to load the settings file in a text editor The editor appears and the dialog is hid den When the text editor is closed the dialog re opens with the newly loaded settings See Figure 2 3 for a snapshot of the settings file loaded
41. Hochschule Bayern framework To this end RealAudio and RealVideo streams were combined with E Chalk board recordings 24See Section 5 2 3 3 9 LOCALIZATION 57 47 AudioWizard Help Viewer lt gt J fieno Gain Control Tuning Please ping all your equipment into the soundcard and switch it on Make sure thers is no feedback Inog and no outside noise Repeat the specified word in about the same intensity lice in an E Chalk lecture Adjust gain at hardware Raise the microphone a Ussa fabric coating tr ding caused by esplosives Figure 3 2 The help browser showing the help page for the audio wizard s step on gain control tuning have also been translated to Turkish see Figure 3 3 To provide the mnemonics for GUI elements and text in the current locale calls to static methods of the class de echalk util Txt are used The class Txt loads a java util ResourceBundle for the locale set E Chalk uses Java s property resource bundles meaning a property file is loaded to map lookup keys to localized entries In addition to using this mapping the loading mechanism of Txt has a special handling for the echalk 110n load key It allows to specify a comma separated list of additional property resource bundles to be loaded These can in turn have such an entry of additional bundles to be loaded and so on allowing to organize the localization data in a tree hierarchy The root property bundle for E Chalk s local
42. Holmer Roomware for cooperative buildings Integrated design of architectural spaces and information spaces In Norbert A Streitz Shin ichi Konomi and Heinz J rgen Burkhardt editors Cooperative Buildings In tegrating Information Organization and Architecture Proceedings of CoBuild 98 volume 1370 of Lecture Notes in Computer Science pages 4 21 Springer Verlag Darmstadt Germany 1998 Norbert A Streitz J rg Gei ler Torsten Holmer Shin ichi Konomi Christian M ller Tomfelde Wolfgang Reischl Petra 186 Shi00 Shn98 SKB92 SM96 SRS 93 SSL 97 Sta81 Ste04 Sti96 Sti97 STMTKO1 BIBLIOGRAPHY Rexroth Peter Seitz and Ralf Steinmetz i LAND An interac tive landscape for creativitiy and innovation In Proceedings of the Conference on Human Factors in Computing Systems CHI pages 120 127 Pittsburgh PA USA May 1999 ACM Press Jack Shirazi Java Performance Tuning O Reilly September 2000 Ben Shneiderman Designing the user interface strategies for effective human computer interaction Addison Wesley third edi tion March 1998 Abigail J Sellen Gordon P Kurtenbach and William A S Bux ton The prevention of mode errors through sensory feedback Journal of Human Computer Interaction 7 2 141 164 1992 Holger Schwenk and Maurice Milgram Constraint tangent dis tance for on line character recognition In International Confer ence on Pattern Recogn
43. JPEG decoding is supported by PDF This is not only much faster than the pixel grabbing method it also returns smaller PDF files 9The mechanism is called mask images by color in PDFs 10PNGs are not used in E Chalk with the default setup see Section 2 4 Still the direct parsing of PNG files in the PDF converter is a desirable future extension 6 1 EXPORT TO PDF 109 6 4 3 2 1 plot t sin t t Pi Pi Figure 6 3 Examples of outlined strokes and text element from a PDF tran script because the raw pixel data of the DCT encoded JPEG images do not compress well with flate encoding Still parts of the JPEG data must be parsed by the converter for two reasons First even though the image dimension and color space like RGB or gray scale is given in the inline JPEG data the information must also be stored in extra fields of the PDF image objects Second inserting corrupted JPEG image data like for example from a truncated file corrupts the whole PDF document stan dard PDF viewers do not display such PDFs For these reasons the converter scans the JPEG data for dimensions and color space and checks the integrity of the image If the image is damaged the pixel grabbing method described above is used as a fall back mechanism as the Java rendering mechanism can also handle truncated files filling in the unknown portions with a background color If the data are damaged so badly that even the pixel grabbing method fails t
44. June 2003 Twelfth EDEN Annual Conference European Distance Education Net work Gerald Friedland Lars Knipping Raul Rojas Joachim Schulte and Christian Zick Die E Chalk Software Einsatz und Evalu ation in Pr senzunterrichts und e Learning Szenarien In Pro ceedings of the First Potsdamer Multimedia Conference Potsdam Germany October 2004 Gerald Friedland Lars Knipping Raul Rojas Joachim Schulte and Christian Zick Evaluationsergebnisse zum Einsatz des E Kreide Systems im Wintersemester 2003 2004 Technical Report B 04 06 Fachbereich Mathematik und Informatik Freie Univer sit t Berlin June 2004 Gerald Friedland Lars Knipping Raul Rojas and Ernesto Tapia Web based education as a result of AI supported classroom teach ing In Knowledge Based Intelligent Information and Engineering Systems Seventh International Conference KES 2003 Oxford UK September 3 5 2003 Proceedings Part II volume 2774 of Lec ture Notes in Computer Sciences pages 290 296 Springer Verlag September 2003 Gerald Friedland Lars Knipping Raul Rojas and Ernesto Tapia Teaching with an intelligent electronic chalkboard In Proceed ings of ACM Multimedia SIGMM 2004 Workshop on Effective Telepresence pages 16 23 New York NY USA October 2004 ACM press Gerald Friedland Lars Knipping Joachim Schulte and Ernesto Tapia E Chalk A lecture recording system using the chalkboard metaphor Interactive Technology and Smart Educat
45. Listing 3 4 Example chalklet bookmark entry referencing the logic circuits simulating chalklet described in Section 6 12 4 Thumbnail data is omitted in this example Audio Profile Wizard Launch For creating a new audio profile in the setup dialog the audio profile wizard application is started See Section 5 2 3 for a description of how the profile wizard works The wizard directly changes the audio profile list when started as a stand alone application Started as a component of the E Chalk setup dialog profiles should only become permanent when the setup dialog is exited with OK or Exit and not with Cancel To this end the setup dialog creates a temporary file with a copy of the XML audio profile list This copy is given to the wizard for modifying When the setup dialog exits with Cancel the original XML file remains unchanged and any newly created audio profile identified by being referenced in the temporary copy but not in the original file is removed If the setup dialog is closed with Exit or if a recording is started with OK the temporary XML file is copied to the path of the audio profile list XML file and any user delete action on the profile list by users is made permanent by removing any now unreferenced profile data file 3 6 Starting a Lecture Recording When a recording is started the output directory is generated and the necessary files for remote access are written like the HTML index file and the Jar archive co
46. RELATED WORK Page Detector Status Display Record Controls Audio Scrollbar T ie y Figure 1 6 An Audio Notebook prototype Figure from SASO1 computerized access to the handwriting and the paper sheets used are marked to be recognized by the device Marquee WP94 is a system for annotating videos with handwritten notes For synchronizing the notes with the video time zones are created using a horizontal line gesture Handwritten keywords are manually converted to text for indexing purposes 1 5 2 Commercial Digitizing Whiteboard Software Most customers of digitizing whiteboards buy the hardware to equip their meet ing rooms As a result the software for these boards focuses on meetings and presentations They build on the standard desktop GUI and allow pen based annotations Some support desktop sharing for interaction with local co workers using personal computers some allow for distributed work For example the products of Centra Symposium 9 and WebEx Training Center 107 aim at presentations to remote audiences Often these tools can save the board content in static pages ACTIVstudio for example that comes with the Promethean ActivBoard 77 allows to save materials as HTML pages or as Microsoft PowerPoint presentations Some even have limited replay capabilities like the software of the SmartBoard from Smart Technologies 88 that is able to do audio recording 1 5 3 Tivoli MeetingBoard The objecti
47. Rainer M ller and Thomas Ottmann Electronic note taking sys tems problems and their use at universities In Heimo H Adels berger Betty Collis and Jan M Pawlowski editors Handbook on Information Technologies for Education amp Training chapter 9 pages 121 138 Springer Verlag Heidelberg Germany 2002 Momenta Momenta User s Reference Manual 1991 Andrew F Monk Mode errors a user centred analysis and some preventative measures using keying contingent sound Interna tional Journal of Man Machine Studies 24 4 313 327 1986 Sugata Mukhopadhyay and Brian Smith Passive capture and structuring of lectures In Proceedings of the seventh ACM inter national conference on Multimedia Part 1 pages 477 487 Or lando FL USA October November 1999 ACM Press 182 MSCM03 MSG98 MvMo0 MvMC98a MvMC98b MW83 Mye00 Mye01 Myn99 Nie99 BIBLIOGRAPHY Mingchao Ma Volker Schillings Tongbo Chen and Christoph Meinel T Cube A multimedia authoring system for elearning In Proceedings of E Learn 2003 World Conference on E Learning in Corporate Government Healthcare amp Higher Education pages 2289 2296 Phoenix AZ USA November 2003 Association for the Advancement of Computing in Education AACE Brad A Myers Herb Stiel and Robert Gargiul Collabora tion using multiple PDAs connected to a PC In Proceedings of the ACM conference on Computer supported cooperative work
48. Schulte conducted the extensive user evaluations on the system in university teaching Stefanie Eule evaluated the usage in K 12 schools For valuable feedbacks I would like to give thanks to many users especially to the MOSES team of Prof Dr Ruedi Seiler and Dr Sabina Jeschke including Erhard Zorn Sven Grottke Robert Luce and others Special compliments should also go to Dr Ulrich Kernbach of the Deutsches Museum in Munich and to the Himmel5 team I owe thanks to Guido Reuter of the MCR GmbH for expert information on board hardware and software for generously providing test hardware and for lots of interesting input For polishing up my English I am indebted to Heike Hellner Gerald Fried land Christian Zick and Peter Monnerjahn Finally for their kindness and support I want express my gratitude to my friends my parents and my beloved Diana Contents 1 Introduction and Related Work 1 1 The E Learning Landscape 1 1 2 EeChalk The Idea ane eaa 288 ee ee a a 5 1 3 Board Hardware sa a da a 4 ee ge eee eee Hw we Ode os 7 13 1 Digital Boards qaa nen wen aan en BAG Gee 8 1 4 Pen Computing Software 2 2 onen ern 9 1 5 Pen based Office and CSCW Tools o 11 1 5 1 Personal Note Taking o 11 1 5 2 Commercial Digitizing Whiteboard Software 12 1 5 3 Tivoli MeetingBoard 2 o o o 12 19 4 Platlando ae ase 2000 20 tee ar Iran
49. TableCellRenderer inter face to be used for rendering the thumbnails in the bookmark editors where the bookmark entries are shown in java swing JTable objects 70 CHAPTER 4 BOARD SERVER Echalk Load Image Bookmarks earth from space math lecture at TU Berlin fal FU Berlin computer science build Latest weather from METEOSAT 2 Gerald Lars F Echalk Load Chalklet Bookmarks 5 Echo Demo Anim horizontal 5 Echo Demo Anim vertical Logicrecognition De ogicrecognition classname de echalk logicrecognition LogicAnimationKit Isre http www online lectures org chalklets logice jar Feedback Disabled false Config File etcVogicrecognition conf Saved Gates Directory etcisavedGates Diagram fa se 2 tes L Christian URL httpvAwww eumets at deimarssimgiil a Figure 4 5 URL bookmark dialogs of the board left with textual input line and button to launch a file chooser right with tooltip for a chalklet bookmark type specific handler objects which manage how they are integrated into the board content Macros are not loaded via the RcLoader The resource loading tasks for the resource loader are triggered in the GUI s event handler thread and because potentially longer actions should never be handled directly in the event handler thread the RcLoader uses a separate thread to handle these tasks As described in Section 2 4 2 a feedback dialog is shown when a
50. Tele TASK CMMS03 MSCMO3 94 tele teaching anywhere solution kit is used for synchronous and asynchronous transmissions of lectures It delivers RealAudio and RealVideo of the lecturer plus a sequence of screenshots nor mally of an annotated slide show by the lecturer The slides are captured at one frame per two seconds For live streaming the slides are streamed as BMP images requiring the remote viewer to use a high bandwidth connection In a post processing step a narrow bandwidth version ISDN or modem is pro duced by encoding the snapshots as PNG graphics utilizing PNG transparency to achieve an encoding into difference and key frames For replay the RealPix technology from RealNetworks 79 is used to stream the slide images and SMIL for synchronizing the different streams The system uses an extra PC for capturing and encoding The solution is available commercially as all in one hardware to be connected to the presenta tion computer under the name t Cube 26Note that t Cube is unrelated to the pie menu based key input system T Cube described in Section 1 4 26 CHAPTER 1 INTRODUCTION AND RELATED WORK 1 9 Conclusion The approach presented here tries to solve the problem of huge costs for creat ing courseware material by generating it as a by product of regular classroom teaching The chalkboard lecture becomes a form of e learning authoring The approach benefits from many professional lecturers being able to sim
51. Ward Alan F Blackwell and David J C MacKay Dasher a data entry interface using continuous gestures and lan guage models In Proceedings of the thirteenth annual ACM sym posium on User interface software and technology UIST pages 129 137 San Diego CA USA November 2000 ACM Press Mark Weiser Some computer science issues in ubiquitous com puting Communications of the ACM 36 7 75 84 July 1993 Special issue on computer augmented environments back to the real world Terry A Welch United States Patent No 4 558 302 High speed data compression and decompression apparatus and method 1983 Sperry Corporation filed June 20 1983 Terry A Welch A technique for high performance data compres sion EEE Computer pages 8 19 June 1984 BIBLIOGRAPHY 189 WGB99 WHW94 Win0la Win01b WJFO2 Wol03 Woo94 WP94 WRB92 WRZO91 WSS97a Mark Weiser Rich Gold and John Seely Brown The origins of ubiquitous computing research at PARC in the late 1980s IBM Systems Journal 38 4 693 696 1999 Steve Whittaker Patrick Hyland and Myrtle Wiley FILOCHAT handwritten notes provide access to recorded conversations In Proceedings of the conference on Human factors in computing sys tems CHI pages 271 277 ACM press Boston MA USA April 1994 Terry Winograd Architectures for context Human Computer In teraction Journal 16 2 4 401 419 2001 Special issue on context awar
52. action being handled in the event handler effectively renders the program non responsive It would not even handle cancel actions from the user until the pending action is finished 8 This is an implementation of the worker thread pattern see GHJV95 4 7 BOARD RESOURCE LOADING 71 an image on the board The LoadTask objects contain the resource loading and decoding imple mentation as well as the methods for accessing information about the current progress to display in the progress cancel dialog a textual message with a lo calized description of the step the loading process is currently performing and a numerical progress if it is available The loading subtask also tries to determine the MIME type of the resource loaded For most requests like using image bookmarks it is known in advance what kind of data will be returned but for CGI requests it cannot be decided a priori which content decoding and handling is needed The system then uses the MIME type information to decide which decoder to use See Figure 4 6 for an overview of the classes involved in board resource loading 4 7 1 URL Loading Many of the board resources are loaded from URLs In the case of CGI scripts there can be also POST arguments given for the URL request For a URL loading task a URL connection is opened any POST arguments are sent sent over and the returned data is read from the connection If the URL is a file URL the URLLoad object does not use
53. an easy to use interface the software can be expected to gain the user s acceptance For the interaction on the board guidelines common for desktop programs will have to be taken with a grain of salt The board explicitly uses a different interaction metaphor and the guidelines sometimes have to be bent keeping their underlying arguments in mind On the other hand new requirements appear for example the use of the keyboard is very disruptive when working with a pen at the board and should be avoided as far as possible Also double 2The Applets need only Java 1 1 to avoid the requirement of a Java upgrade for the browser and they need not be signed 3 Again the given bandwidth is for the default setup 2 2 USABILITY CONSIDERATIONS 29 clicks should not be required Some persons already have trouble doing double clicks with mice and these are even more difficult to do with pen input devices Control by Keyboard Common usability guidelines recommend that an application should be fully controllable with the keyboard with no need to use the mouse Reasons are that expert users will often be faster with keyboard only inputs and that one should still be able to control the program in the absence of a pointing device Consequently the E Chalk setup dialog and all its sub dialogs provide mnemonic keys for all input elements 4 However this does not hold true for the main board operations painting and handwriting These cannot be na
54. and Nitin Sawhney Dynomite a dynamically organized ink and audio notebook In Steven Pem berton editor Proceedings of the conference on Human factors in computing systems CHI pages 186 193 ACM press Atlanta GA USA March 1997 190 wss 97b Yan83 ZBC02 Zhu97 ZL77 ZL78 ZS02 BIBLIOGRAPHY Lynn D Wilcox William N Schilit Nitin Sawhney Joseph W Sullivan and Timothy W Bickmore United States Patent No 5 970 455 System for capturing and retrieving audio data and corresponding hand written notes 1997 Xerox Corporation filed on March 20 1997 Robert J Yannes United States Patent No 4 677 890 Sound interface circuit 1983 Commodore Business Machines Inc filed on February 27 1983 Richard Zanibbi Dorothea Blostein and James R Cordy Rec ognizing mathematical expressions using tree transformation IEEE Transactions on Pattern Analysis and Machine Intelligence 24 11 November 2002 Chad Zhu RFC 2190 RTP Payload Format for H 263 Video Streams TETF TESG September 1997 Jacob Ziv and Abraham Lempel A universal algorithm for se quential data compression IEEE Transactions on Information Theory 23 337 342 May 1977 Jacob Ziv and Abraham Lempel Compression of individual se quences via variable rate coding IEEE Transactions on Informa tion Theory pages 530 536 September 1978 Peter Ziewer and Helmut Seidl Transparent teleteaching In Andy Williamson Cathy Gunn
55. be executed for all Applets before the next step is performed realizing a simple barrier synchronization For example all Applets must be constructed and made accessible via the stub setting before the Applets are initialized where they may try to access other Applets See Listing 4 1 for details When an Applet is removed from the board for example by a clear all event or by rewind on the client it is removed from the component list of the Draw Panel its stop and destroy methods are called the thread the Applet were started in is stopped and all references to the Applet and its classes are cleared According to Java s implementation advises on Applets the destroy method should release any resources the Applet used like extra threads and they can then be garbage collected Unfortunately it seems that few of the Applets around in the Web adhere to Java s implementation guide 4 10 1 Applet Events To be able to transmit the user interaction to the remote clients the AWT events on the Applet s components have to be logged To do that AWT listeners are registered to the Applet and recursively to all its subcomponents When a listener is notified of a low level AWT event happening it registers the event to the board for storing thus the remote client can recreate the event to be handled While the lecturer s basic interaction with the Applet can be reproduced this strategy has a number of problems with achieving an exa
56. be introduced by the sound equipment Hard disks and fans in the recording computer produce noise cables can cause electromagnetic interference that results in noise or humming Feedback loops can also be a problem if the voice is amplified for the audience The lecturer s attention is entirely focused on the presentation so that tech nical problems like just forgetting to switch the microphone on are easily over looked Weak batteries in the microphone cause a drastic reduction in the signal to noise ratio often without the speaker noticing Many people also have problems with the operating system s mixer It differs from sound card to sound card and from operating system to operating system and usually has many knobs and sliders with potentially wrong settings Selecting the right port and adjusting mixer settings can take even experienced users minutes Another subject is equipment quality Some sound cards cannot deliver high fidelity audio recordings In fact most sound cards focus on sound playback but not on sound recording Games and multimedia playback are their most important applications On board sound cards especially those in laptops often have very limited recording capabilities The quality loss introduced by modern software codecs is perceptually neg ligible compared to the problems described above Improving audio recording for lectures held in lecture halls means first and foremost improving the quality of the input sig
57. board data is stored as the timestamped vector data given by the original board events This avoids huge bandwidth and blurring of sharp edges in the board image that would result from generating a standard video stream format based on DCT compression On the other hand this introduces the need for installing a DirectShow plug in for Windows Media Player enabling it to decode the events for video playback See Figure 6 6 for an example of a replay The implementation of the decoder plug in can handle the most frequently used board events line drawings pasted images scrolls Also text events are partially handled typed text is supported but the dynamic line breaking provided by the board is missing as well as handling of cursor movements and backspace and delete Clear all requests Applets and undo redo events are not implemented either While this approach requires the user to install a plug in it has the advantage of preserving the lossless representation of the board stream and thus enjoying the advantages of clear board drawings with low storage space requirements For encoding the audio stream the standard encoders from the Windows Media API can be selected However decoding the E Chalk encoded audio and re encode it with another codec decreases the quality of the audio stream Also the available codecs are often less specialized to speech data than the E Chalk audio codec The quality of the audio stream usually decreases significa
58. causes the board to stall if the event reader has not yet read the events up to ty At Fortunately this is usually only the case if a replay is forwarded a considerable amount of time at the very beginning of replay and even then only for a short time because the board event data are relatively small in size Because there is no general reverse mechanism for a board event jumping back to a offset of to At is realized as a total rewind jumping to offset zero by clearing the whole board and then jumping forward to ty At To speed up jumping to a new offset the changes in the board content are not shown immediately Instead the changes are applied to the offscreen buffer Intermediate changes are only shown by repaints during lengthy VCR operations when the adjustment takes more than one second to realize and only in steps of one second giving the user some feedback that the board is still active The board also signals the user to be busy during the adjustment by changing the mouse pointer to a wait pointer 7 2 3 Scrolling The server board can be scrolled with mouse drags by the drag handles while other mouse drag actions are used to draw on the board The client board which the remote viewer cannot paint on allows to do scrolling type drags everywhere on the board To give a feedback to the user the mouse cursor changes to move pointer defined by the operating system once he or she starts to drag Horizontal drags are a
59. circuits chalklet simulating a clocked RS Flip Flop High inputs are shown with red lines low inputs with blue lines A state timing diagram for the circuit is shown at the bottom left Figure from Liw04 The chalklet usability has been tested in a video taped laboratory test Eight users with different background knowledge about logic circuits and the E Chalk system got a 15 minute introduction into logic circuits and using the chalklet Then they received a number of exercises requiring them to use the chalklet Afterward they were interviewed for their experiences and opinions Some minor interface flaws in the chalklet were identified in the test notably of features not being being recognized as connected by wires due to the rec ognizer s distance tolerance being to small and in the workflow for storing circuits for reuse The feedback resulted in certain adjustments being made to the chalklet See Liw04 for details 6 12 5 Python Interpreter Python vRD03 78 is a programming language that was conceived as a teaching language The technical overhead from language syntax is very small compared to most other languages Python programs look very similar to algorithms in pseudo code notation The idea of building a Python interpreter chalklet came in mind when Computing Science lecturers were looking for a tool to interactively teach programming and algorithms with E Chalk Hence a Python interpreter chalklet was developed Ste0
60. displaying the manual when it is started from the boards tool dialog When the help is started from within E Chalk the browser shows the help section relevant to the subcomponent it was started from providing basic con text sensitivity for the help system For example when it is started from the audio profile wizard it opens the help page at the section describing the cur rent wizard page accessing the different help sections by the use of HTML anchors See Figure 3 2 for an example The built in browser implements the Launchable interface and can therefore also be started from the E Chalk command line console see Section 3 10 1 3 9 Localization The user interface of the E Chalk server application and its installer is in ternationalized including subcomponents like the E Chalk board Only those software tools and documentations provided exclusively for developer use have an English only interface These include the command line console described in Section 3 10 1 the internal message log described in 3 10 2 the included API documentation and the comments in the configuration files Localizations realized are English US variant and German DE variant An old version of the server is also available in Spanish and parts of the interface 23 This feature was actually requested by the department of Economics at Universit t Re gensburg Multimedia supported lectures were produced at the department in a project of the Virtuelle
61. eClass Georgia University developed a technology originally named Classroom2000 and later renamed to eClass Abo99 Bro01 14 It records lecture slides and hand written annotations as static Web pages together with audio and optionally video recordings of the instructor and any Web page he or she visited during the lecture The presentation component ZenPad handles showing slides in GIF or JPEG format added beforehand in a pre production phase as well as freehand annotation Empty slides can be added during the presentation to be used as a whiteboard Any Web page URL the lecturer visits is recorded by having the demonstration Web browser use a custom proxy server Audio and low quality video of the lecturer are encoded in RealVideo and RealAudio 25 ZenPad is a pure Java successor of the original ClassPad program written in Visual Basic The ClassPad application produced static annotated slides but involved manual upload and structuring of lectures with about four man hours per lecture ZenPad was developed to have an automatic upload and to support certain replay features 24 CHAPTER 1 INTRODUCTION AND RELATED WORK Be Du onen Dono EEN MIA ee Bal fa AI A GrafikRahmen extends Frame public static String args Problembeschreibung a GrafikRahnen wnd new GrafikRahnen Gegeben Of n Objekte der Gr en sing WindowEvent event mit 0 lt s lt 1 f r 1 lt i lt n D setBackground Col
62. file and optional skin data for the VCR control Applet are specified Optionally a list of files to be copied to the lecture recording directory can be specified too for example for images to be embedded by the HTML files The templates are a mixture of literate HTML and interpreted code The code parts are enclosed in brackets Within the code area parts can be aggregated to blocks by enclosing them in brackets Literate strings in the interpreted section are marked by enclosing pairs of quotes or double quotes Tokens which are not literals predefined keywords brackets or operators are interpreted as variables For a variable the value of the Property with the variable name defined in the E Chalk system is used or the empty string if it is undefined For property lookup the lecture settings and the startup config uration properties are used In addition a few runtime properties are defined like time date and in templates for replay from archive the values of the recorded lecture s length Supported statements in the template code are if else statements with a syntax similar to Java and a statement for setting a property variable in the context of the template with syntax being set lt varname gt lt value gt All other statements are terms formed by literates variables or operators on sub terms and are interpreted as output of the corresponding values Supported operators are the comparison operators not equal
63. front view on the lecturer on a stage one fixed at a projection screen for a slide projection and a third looking at the lecturer from a side view Multiple microphones are used usually at the stage in the auditorium and optionally a wireless microphone worn by the speaker The system mixes the sound signals tracks the lecturer with the cameras looking at him or her and uses a heuristic approach to switch between different cameras For example it shows the view on the slide projection when a new slide appears We Met WRZO91 WRB92 window environment meeting enhancement tool is a tool for an electronic whiteboard to show slides with pen annota tions Interactions are stored for replay but audio capturing is not supported Handwriting is saved as timed vector data keeping its storage size small 1 8 1 Desktop Grabbing Applications that grab desktop activity and store them as video for replay can be used to record lecture presentations especially if they allow to record the audio of lecturers narration and have tools for adding annotations For example Camtasia Studio 8 by TechSmith Corporation 92 is a commercial Windows 2000 XP application for real time screen recording and synchronized audio It also allows place marks with cursor highlights and in a post production phase captions text boxes and graphics can be added To avoid the detrimental 1 8 LECTURE RECORDING 21 Tegrity Instructor Interacting with Content ES
64. in the setup Other requests concerned distribution of lecture recordings on CD ROM and archives for E Chalk material to make recordings from former terms available The lecturers interviews showed that most board features were used rarely except for the basic writing features and including of images Instructors pre ferred the eraser to the undo function However switching between pen and eraser for minor corrections was cumbersome In reaction to these findings the possibility to toggle between eraser and drawing tool by the right mouse button equivalent to the extra button on the pen of the Numonics whiteboard used in most TU lectures was added All lecturers used a black board back ground Their preferred writing color was green as it offered a good contrast both to the black background on the board and to the white background of the PDF transcript There were some complaints about several colors having bad contrast in the PDF due to the background color change and about the PDF page separation running through writing This caused the introduction of the outline feature for the PDF contents see Section 6 1 3 and a page separation algorithm that considered the vertical distribution of the contents described in Section 6 1 Another suggestion for improvement was a preview function for images re alized as a thumbnail option for bookmarks Lecturers would have liked to This feature is active in the default setup but can be
65. interfaces for informal and oppor tunistic meetings Technical Report GIT GVU 99 06 GVU Cen ter Georgia Institute of Technology January 1999 Michael J Black Francois B rard Allan D Jepson William New man Eric Saund Gudrun Socher and Michael Taylor The digital office Overview In Proceedings of the 1998 American Association for Artificial Intelligence AAAI Spring Symposium on Intelligent Environments Palo Alto CA USA March 1998 Dave Berque Terri Bonebright and Michael Whitesell Using pen based computers across the computer science curriculum In Pro ceedings of the thirty fifth SIGCSE technical symposium on Com puter science education pages 61 65 Norfolk VA USA March 2004 ACM Press session on new technologies for classroom in struction Carsten Bormann Linda S Cline Gim Deisher Tom Gardos Christian Maciocco Donald Newell Jorg Ott Gary Sullivan Stephan Wenger and Chad Zhu RFC 2429 RTP Payload For mat for the 1998 Version of ITU T Rec H 263 Video H 263 IETF IESG October 1998 Narcisse P Bichot Kyle R Cave and Harold Pashler Visual selection mediated by location Feature based selection of non contiguous locations Perception amp Psychophysics 61 3 403 423 1999 Dorothea Blostein and Ann Grbavec Recognition of mathematical notation In P S P Wang and H Bunke editors Handbook on Optical Character Recognition and Document Analysis chapter 22 World Scientific Publishi
66. is even more complex New entries are created in a dialog It expects the URL where the chalklet s code should be loaded from and the name of the ChalkletKit class to produce the chalklet instance To make the setup easier the Create Bookmark dialog allows to auto matically search the classpath URL for all ChalkletKit classes After that a dialog showing the properties can be displayed the meta information defined by the kit is shown and input components for the parameters expected by the kit are provided see Figure 2 5 Audio Settings The audio settings page allows to select a codec to be used for the audio stream see Figure 2 6 The page also provides a list of audio profiles An audio profile is used to tune the recording for quality depending on the information on audio hardware and speakers frequency range stored in the profile See Section 5 2 for details The Button labeled Create starts the audio profile wizard to generate 13See Section 4 6 4 for a technical description of chalklet programming 14An alternative approach would have been to require the chalklets to be packed in a Jar archive together with meta information specifying the ChalkletKit s name This approach is often pursued in component based programming for example for Java beans or for Os car OSGi bundles However the need for meta information can be confusing for beginners The required packing also introduces an extra step for developers This can b
67. is positioned behind each display The camera signals are fed into a second PC which searches for the laser pointer s signal computes a mouse position from it and sends the position to the display handling computer A receiving program acts as a mouse driver setting the mouse position accordingly For a detailed description see Die03 However this solution only provides a kind of zero button mouse To add more features to the pen the driver has been enhanced to handle additional signals sent via bluetooth see Reb04 The extra space of the data wall are used with E Chalk to show previously 146 CHAPTER 8 EXPERIENCES AND EVALUATION Figure 8 3 Left Digitizer tablet with integrated LCD tablet Wacom Cintig integrated into a lectern at the the Computer Science lecture hall at Freie Uni versit t Berlin Right Digitizer tablet Wacom Graphire used at a German high school the Erich Hoepner Oberschule in Berlin developed parts of the board lecture giving the classroom audience more context information see Figure 8 4 Only the rightmost quarter of the display is used by the lecturer for drawings Allowing contents to be added to the other three screens would result in problems with replay on displays with regular resolution The three passive windows shown in addition to the default E Chalk screen are realized as E Chalk clients replaying the live stream An Applet parameter causes them to display the content shifted vertically b
68. is to record the mouse pointer all the time Displaying it on the client side would fit into the philosophy of delivering the same information to the learner in the classroom and to the remote user It does not require the lecturer to adapt his or her teaching to the technical requirements of the remote viewer Constantly capturing the mouse pointer position results in extra data to be transmitted but the data volume in question does not exceed the levels reached for drawing events As shown in the bandwidth analysis in Section 4 10 1 the actual data volume is negligible given the event rates delivered by standard pointing devices Chalklet Support The chalklet concept is a quite recent addition to the E Chalk system and therefore the API library for chalklet developers and the underlying chalklet management are at an early stage of development In the future chalklet code should be restricted using Java security mecha nisms like the java lang SecurityManager The execution of chalklets should be secured by concepts similar to Java Applet execution is in browsers running them in a secure sandbox This would protect the main E Chalk application against malignant chalklets for example preventing chalklets from terminating the whole application by calling System exit int However some restrictions posed on Applets like prohibiting file access and very restricted network access might turn out to be too restrictive for productive chalklet
69. lasers to track the reflective bands of the pens and erasers Different pens have different reflective patterns so that they can be distinguished The Webster TS Series from the same company uses resistive sensors The StarBoard Series from Hitachi Software 35 features both front and rear projected whiteboards Some of the pen tracking systems for the front projection systems are based on electrical induction others use a combination of infrared and ultrasonic tracking The rear projected StarBoard R 70X tracks the pen with an infrared laser 1 4 Pen Computing Software A number of pen input metaphors have been considered including writing in notebooks for example Filochat WHW94 and Dynomite WSS97a both de scribed in Section 1 5 1 on cocktail napkins GD96 or onion skins Kra94 the flip chart metaphor e g Flatland IMEL99 see Section 1 5 4 or the oil painters palette and easel metaphor see M Pad Rek98 in Section 1 5 7 The 15A project spawned from these experiments for developing GNU Linux driver for several whiteboard interfaces including Mimio 19 16Even worse in one of the schools where the use of digitizing boards was evaluated within the CidS Computer in die Schulen project see Section 8 1 the eraser tool was stolen causing the board to interpret all writing actions as being done with the eraser A dummy had to be put into the eraser tray as a workaround 10 CHAPTER 1 INTRODUCTION AND RELATED WOR
70. lectures which include a video of the instructor share a psychologi cal problem with conventional distance lectures consisting of slides plus video stream Although every human being has only one locus of attention Baa88 Ras00 the attention of the remote student is led to two areas of the screen the video window and the board or slides area Hence it was tried to separate the video image of the lecturer from the background The image of the instruc tor can then be laid over the board creating the impression that the lecturer is working directly on the screen of the remote student Mimics and gestures of the instructor would appearing in direct relation to the board content Ideally the image of the lecturer can be made semi transparent or even turned off as illustrated in Figure 5 9 The first approach to separate the lecturer s image from the background used an observation from the WWV video encoding blocks stored in the difference frames almost always contained the lecturer s image Changes in board content rarely result in differences the encoder rates as significant However the differ ence frames seldom contained the complete image of the instructor and parts of the background might be briefly obscured by a moving lecturer only to appear again later To compensate for these effects the background was learned by storing repeated similar blocks into a block cache with a least recently used 12Strictly speaking the term
71. may be ignored by some codecs w lt n gt frame width preserves aspect ratio unless h is given may be ignored by some codecs h lt n gt frame height preserves aspect ratio unless w is given may be ignored by some codecs vV verbose output of progress d debug mode makes error output more verbose To get the available codecs listed two other Launchable command line ap plications are included in the echalk tools video package LsAviCodecs for an alphabetical list of all AVI codes and LsQtCodecs for the QuickTime codecs Most video codecs suffer from quality problems introduced by dropping higher frequency parts of the frame images as discussed in Section 1 1 However note that the encoded board stream is significantly superior in visual appearance to encoded video taped material because the encoded signal is much cleaner Re encoding the audio faces the problems already described for the conver sion for playback with Windows Media Player see Section 6 2 6 4 CREATING BOARD SNAPSHOTS 113 Figure 6 7 shows the playback of a lecture converted to AVI The original E Chalk recording has a size of 39 MB for about 96 minutes 37 MB of the data were allocated by audio data The board used a resolution of 1016x740 The AVI video is encoded with the ms mpg4 v2 encoder using 24 bit color and 25 frames per second and uncompressed 16 bit mono PCM audio The AVI has a size of 255 MB 164 MB of that being allocated by the audio 6 4 Creati
72. ne een 13 1 5 5 LAND and FLUIDUM 14 1 5 6 IRoom I Workspace 2 2 22 nennen 14 1 5 7 Other CSCW Systems 15 1 6 Course Authoring Systems 222 Hmmm 16 LET MANIC a SB epee a de AA a 16 1 6 2 Cornell Lecture Browser 2 22 20 17 16 35 AU dG a 2 4 a a ee oe SO a Gaa 17 1 7 Presentation and Classroom Enhancement 18 1 7 1 BIRD Note taking System 19 1 7 2 ConferenceXP Presenter Classroom Presenter 19 1 8 Lecture Recording 20 1 8 1 Desktop Grabbing o 20 1 8 2 Just In Time Lectures o o 22 Star Notebook a dai e dr eS eh ate ek Sa 22 1 8 4 DEBBIE DyKnow 2 2 2222 nen 23 1 8 5 Classroom 2000 eClasS o o o 23 Bo ADE a na es ae Bern er 24 13 0 Letur 2 2 2 ae ee Se ea a e 25 1 8 8 Tele TASK t Cube 2 2 2222 25 159 Conclusion a 22 4 2 A ee a ag 26 2 User Interface 27 2 1 Overview wur u oa RE A AR A A 27 2 2 Usability Considerations 2 22 Comm o 28 2 3 Installing Be Chalke oda auge sr er ne Ge 32 2 4 The E Chalk Server Application 32 241 Setup Dialog vn Nas a ar 33 vi CONTENTS 2 4 2 The Board Component 24 38 2 5 Remote Access 2 Common 43 The E Chalk Application 45 3 1 Main Configuration 2 0 0 00 0 0 000 45 3 1 1 Dynamically Loaded Cl
73. of the fourteenth annual ACM symposium on User inter face software and technology UIST pages 21 30 Orlando FL USA November 2001 ACM press BIBLIOGRAPHY 177 Gui02 Gwoo GWW00 Hay03 HC04a HC04b HD02 HD03 HD04 Hen98 Fran ois Guimbreti re Fluid Interactions for Wall Size Displays PhD thesis Stanford University Department of Computer Sci ence January 2002 Fran ois Guimbreti re and Terry Winograd FlowMenu combin ing command text and data entry In Proceedings of the thirteenth annual ACM symposium on User interface software and technology UIST pages 213 216 San Diego CA USA November 2000 ACM press Fran ois Guimbreti re Terry Winograd and Sha Xin Wei The geometer s workbench An experiment in interacting with a large high resolution display Technical Report CS TR 2000 05 Stan ford University Department of Computer Science May 2000 Simon Haykin Cocktail party phenomenon What is it and how do we solve it In European Summer School on ICA Berlin Germany June 2003 Richard S Hall and Humberto Cervantes Challenges in build ing service oriented applications for OSGi IEEE Communications Magazine 42 5 144 149 May 2004 Richard S Hall and Humberto Cervantes An OSGi implemen tation and experience report In Proceedings of the First IEEE Consumer Communications and Networking Conference CCNC Las Vegas NV USA January 2004 Tracy Ham
74. of the text When the user presses the enter key the text form is closed by a timestamp Text End string event and the cursor is removed The string text stored in the event is the MIME encoded final content of the text form including any line breaks from the board s dynamic line breaking The client board does not need this information for replay but it is used by the PDF converter With this extra field the PDF converter does not have to recalculate the text layout from the automatic line breaking done by the board A text is also automatically closed when a new Form is created or when an Undo event happens This means there can never be more than one TextForm receiving key input A key input of the printable character c for an open TextForm is represented as timestamp Text Char c with c being MIME encoded Some control characters backspace and delete and the cursor moving left and right arrow keys have their own events timestamp Text Backspace timestamp Text Delete timestamp Text Left timestamp Text Right When the user sets the whole text content using the text history with the up and down arrow keys the event timestamp Text SetTxt string is used to set the TextForm s content to the content of the MIME encoded string For pasting from the clipboard a string is inserted at the current cursor position The event timestamp Text Str string 4 12 LIVE SERVER 91 with the MIME encoded string is used Finally fo
75. old content After hiding the setup dialog each component is started in a different thread and execution blocks until the board thread returns as the board component is the only one that allows the user to end the session If the board is not among the recording components started an indeterminate progress dialog with a stop button is shown instead see the part on recording in Section 2 4 If starting the recording fails for example when there is no write permission on the output directory a localized error message is presented to the user and the setup dialog reopens enabling the user to change any erroneous settings and retry to record When the recording was successful the output directory is set up for archived access First the PDF version s of recorded board data is are generated again relying on the board to PDF converter being realized as a Launchable See Sec tion 6 1 for details The length of the recorded lecture streams is determined and with this information the HTML index file for the archived replay is generated as described in Section 3 7 19Like the recording components the converter is started by using the Launchable interface To be more specific the conversion is implemented using the Progressible sub interface of Launchable allowing to show a feedback on the conversion progress See Section 3 10 1 for a description of the interfaces For a description of the old WWR2 and the new WWR3 audio format see Sectio
76. on existing lectures recorded with the old format When a user chooses to append to such a recording the audio format is upgraded showing a progress dialog with a cancel option during the process When executed as a stand alone application it allows to define an audio profile for basic noise reduction and to choose the codec by its bandwidth usage gt java wwr2wwr3 Wwr2wwr3 lt options gt lt infile gt lt outdir gt options p lt profile gt c lt codec gt p lt profile gt audio profile for sound quality improvement c lt codec gt one of 128 64 48 32 kbps 128 being lossless default tries to conserve bandwidth 15 Portable PixelMap PPM is the color image format from the netpbm 67 package 16See Section 5 2 for creating and using audio profiles 114 CHAPTER 6 TOOLS CONVERTERS ADD ONS When executed as a Progressible from the main E Chalk system to upgrade the lecture to append the system assumes the audio profile selected to be ap plicable to the old recording as well speaker and recording equipment should be the same in both The current profile will be used for the conversion The upgrading process chooses the lowest bandwidth for the codec that is not lower than the original bandwidth This should preserve the original quality with out increasing the data volume too much The same behavior is used for the command line application when no codec option is given 6 6 Repairing Damaged Recordings From
77. pages 68 75 Palermo Italy May 2000 ACM press Takeo Igarashi Elizabeth D Mynatt W Keith Edwards and Anthony LaMarca Demonstrating flatland user interfaces In CHI 99 extended abstracts on Human factors in computing sys tems pages 27 28 Pittsburgh PA USA May 1999 ACM press Demonstration session advances in graphical interaction International Telecommunication Union Geneva Switzerland ITU T Recommendation G 711 Pulse code modulation PCM of voice frequencies November 1988 International Telecommunication Union Geneva Switzerland ITU T Recommendation G 726 Adaptive differential pulse code modulation ADPCM December 1990 BIBLIOGRAPHY 179 IS092 U97 Jes00 Jes01 Jes03 JFKO03 JFRO4 Joh00 JRV 89 JSS98 Kat02 KF98 ISO IEC JTC1 SC2 WG10 Digital Compression and Coding of Continuous Tone Still Images January 1992 Draft International Standard 10918 1 Hiroshi Ishii and Brygg Ullmer Tangible bits towards seamless interfaces between people bits and atoms In Steven Pemberton editor Proceedings of the Conference on Human Factors in Com puting Systems CHI pages 234 241 Atlanta GA USA March 1997 ACM Press Chris R Jesshope Using AudioGraph in on line teaching In Pro ceedings of the fourth International Conference on Open Learning Brisbane Australia December 2000 Chris R Jesshope Cost effective multimedia in on line teaching E
78. provided but the board recordings were made available for replay together with the PDF version of the board image Audio was not recorded due to audio recording hardware not being installed in the lecture halls at that time The surveyed FU lecture was held at the Computer Science department Here E Chalk was not used in classroom teaching Instead the lecturer used the system to record the content of lectures in advance The recording of board and audio stream and the PDF transcript were made available for revision purposes All lecture materials were put into a learning management system which gave some statistics on the student s access to the materials as an additional data source 4The LMS used was Blackboard 4 150 CHAPTER 8 EXPERIENCES AND EVALUATION data source observed group notes 595 questionnaires ca 1100 students start April May and end July of summer term 2003 893 short ca 900 students coupled with exam July 2003 questionnaires 6 interviews 6 instructors July 2003 Web accesses to 80 FU students by log file analysis for April to E Chalk material July 2003 Table 8 2 Data gathered by the first evaluation on E Chalk Sch03 All six lectures had an exam at the end of the term To evaluate E Chalk s influence on exam results the participants were asked about how much prepa ration they had done for the exam In addition to the surveys on the students opinions the six lecturers
79. s screen because of its resolution being too low For replay from the archive an additional Applet is opened to provide VCR like controls allowing to pause and resume to fast forward and rewind and to jump to any point in the recording timeline In contrast to the live transmission this type of access does not connect a remote E Chalk application Instead the replay relies on the file streaming capabilities of the Web server In addition to the dynamic board recording a PDF transcript of the board recording is provided to print out the board content comfortably See Figure 2 16 for examples of replay and the PDF version 31The dragging is similar to the server side drags using the board s drag handles It just allows to start a drag anywhere on the board surface drags are not interpreted as drawings on the client board 32The client Applets process the streamed data i e they do not need to load the full recording before starting to play Chapter 3 The E Chalk Application This chapter describes the system architecture and implementation of the main E Chalk server application The user front end of this main part is the setup dialog described in Section 2 4 1 It handles the settings for the E Chalk ses sion and controls the subcomponents board audio and video as well as the subcomponent for creating the PDF transcript The setup of the main application is represented as java util Properties and is stored in the Ja
80. screen being smaller than on a traditional board For a discussion of this problem see discussion of commentaries in the main findings part of Section 8 4 2 e A lower attendance rate at classes is highly significant with an error probability of less than 1 The original German statements were Das Thema dieser Veranstaltung halte ich im Rahmen meines Studiums f r sehr sinnvoll and In der Veranstaltung wurde zu viel Stoff behandelt The question on the number of class attendances was An wie vielen Sitzungen der Veranstaltung haben Sie nicht teilgenommen 156 CHAPTER 8 EXPERIENCES AND EVALUATION hone not specified 1 unknown others 5 Opera 5 modem 31 44 Mozilla Netscape 21 ISDN 17 Figure 8 10 Results on the technical equipment of students questioned in the winter term of 2003 04 qualitative study Left Internet access types Right preferred Web browsers 8 4 2 Qualitative Study on E Chalk Courses The evaluation target was to further explore how and when extra offers by E Chalk were really used by students and to get their opinions on the sys tem Questions were posed about the computer equipment of users their usage pattern of E Chalk materials and the quality of the software both in general and in comparison with other teaching technologies Only the main findings of the evaluation are presented here A more detailed listing can be found in FKR 04b Evaluated Courses N
81. server see Figure 8 5 Board and lecturer s voice were recorded as an E Chalk lecture 2See yoffset parameter described in Section 7 2 5 8 1 CASE STUDIES 147 Figure 8 4 Left Geology seminar at Freie Universitat Berlin using a rear pro jector with laser tracked pen Hitachi StarBoard R 70X and several tablets Wacom Graphires Right The data wall constructed at the Computer Sci ence department of Freie Universitat Berlin Except for such special situations however the demand for live transmis sions is marginal Most students who do not visit the lecture prefer to view the recording at a later time especially as the live transmission does not really give them an extra benefit To add extra value to the live transmission a commu nication tool like a chat line may be added to the HTML pages perhaps even with a lecturing assistant joining the chat According to feedback from learners the preferred use of E Chalk recordings is exam preparation The material is also used by learners who did never visit the recorded lecture itself A student at Fachhochschule Trier for example used recordings of lectures on Neural Networks from Freie Universitat Berlin to prepare for his final exam and afterwards contacted the E Chalk team members sending a bottle of wine to thank them Also at least one Berlin student was not able to visit this very Neural Networks lecture due to lectures collisions but instead relied purely on the
82. symbol has links to other baselines symbol lists which satisfy the spatial relations mentioned above The method in Mat99 describes a minimum spanning tree construction for groups of strokes considering the centers of the stroke bounding boxes as nodes of a completely connected weighted graph with a custom weight function The approach is robust in terms of stroke grouping but not in terms of structural analysis so the algorithm is used in the recognizer to build the baseline tree which is then recursively changed to take the constraints of the above described spatial relations into account TR04 See Figure 4 14 82 CHAPTER 4 BOARD SERVER 7 2 2 ee tey x f u Ma en Ey o Pda Ma AA Y i y Y 2 y Mn ZA 2 YT Re ar A A a TT ee aP Ampy he ar Y Crd T a Figure 4 14 Left Baseline tree after the first recursion Right Final tree of spatial relations 4 10 Applet Control As mentioned in Section 4 7 3 any Applet added to the board content is loaded by an instance of a custom ClassLoader This object saves a local copy of the loaded classes to make them available for the client board Applet see Section 7 2 4 The board then acts like a kind a Java enabled browser for the Applet It constructs an instance of the Applet using the default i e the parameterless constructor and then sets a java applet AppletStub by calling the Applet s setStub method The AppletStub and the java applet AppletContex acces sible throug
83. the concatenation of their string values See Listing 3 6 for an example template Besides user defined text and layout changes the templates can be used to add other elements like a chat line in the live page to communicate with the lecturer or a teaching assistant It can also be used to adjust the E Chalk client s behavior for example to set a client parameter that results in the client board being displayed embedded in the browser window instead of opening a new frame For another usage example see the setup with three live board clients described for the FU data wall in Section 8 1 1 3 8 Help System E Chalk s user manual is installed in HTML format When the user accesses the help the system displays the manual in a simple browser which is part of E Chalk Early versions of E Chalk used an external browser application instead of its own which uses the Java Swing HTML rendering engine In E Chalk s early history the browser model could be guessed with high accuracy from the operating system simply assuming the Netscape browser for Unix platforms and the Internet Explorer on Windows Nowadays it is no longer that easy to determine a browser to use automatically as the HTML viewers have become to manifold on Linux systems for such a simplistic approach and E Chalk provides its own one instead For historical reasons there is still the echalk htmlviewer entry in the conf echalk conf which can be changed to use another browser for
84. the remote user to trigger the slide transition manually or their display is synchronized with the audio video stream Some specialized lecture recording tools allow to give presentations and automatically store the transitions for replay others require to add the transition times by extra manual effort in a post processing phase Teaching with Slideware or Desktop Environments Teaching with slideware tools like PowerPoint is prevalent regardless of the lectures being recorded or not However this has been heavily criticized Cre97 The advantage of slides is their easy reuse and the wide availability of slideware tools on computers On the other hand they are devised for presentations and not for teaching Edward Tufte argues that PowerPoint is a good tool to convincingly sell something while complex arguments tend to get lost Tuf03a Tuf03b As stated by Richard Clark the human brain can be easily overloaded by the sensory input that e learning and multimedia technology is capable of gen erating Cla99 While obviously there are people who can give great classes using slide presentations these tools foster a tendency to overwhelm learners with rapid deliverance of information The lecturers of course already have a deeper understanding of the subject and they often tend to continue with a speed too fast for their students to follow when not restrained by the teaching tech nique Also classes given with slideware tend to be m
85. to Physics TU 300 113 107 220 for Engineers sum 1070 428 167 595 Table 8 1 Questionnaires returned from lectures having been evaluated during the summer term of 2003 8 3 Studies During Summer Term 2003 Methodology The main source of data for the evaluation Sch03 were questionnaires filled out during the lectures See Table 8 1 for a detailed listing The TU Berlin lectures were held in the context of an e learning project named Moses 64 As the students were also asked to take part in evaluations for Moses and for the regular teaching evaluation by the department their load of questionnaires was quite high To avoid irritations it was decided to skip the survey at the end of the term for three of the lectures 595 questionnaires were evaluated and 52 students were identified to have answered the questions twice at the start and at the end of the term Their responses were examined for changes of attitude The lectures at TU Berlin were held at the departments of Mathematics and Physics In his Introduction to Physics for Engineers the instructor used an LCD digitizer tablet for pen input and the board image was shown to the audience using an LCD projector In the other four TU lectures a digital whiteboard with front projection was used together with a second projection for the audience This setup installed at TU Berlin in several lecture halls is shown in Figure 8 2 Live transmission of the lecture was not
86. to display the average and worst case bandwidth in the setup dialog both for individual streams and in total 2 4 THE E CHALK SERVER APPLICATION 37 El Echalk 2 General J Board 9 Audio El Video D Live Server PoF Osprey 500 Card 1 STV0673 Camera screen grabber video test image Input Device Rescan Rescans System for Installed Video Devices ants 176144 somo 320240 352 288 Framerate Figure 2 7 The video settings page PDF Settings In the settings for the PDF version of the board lecture paper orientation and format of the produced PDF can be selected Regardless of the background color used for the board the PDF may be produced with white background to save printer color See Section 6 1 3 on provisions taken to preserve a good contrast of the writing against the white background Finally the setup allows to generate a grayscale version of the PDF for black and white printing a color PDF or both See Figure 2 8 for a snapshot on the PDF page Recording When the OK button is hit to start a recording the system checks if the output directory already contains a recorded session In this case the user is queried if E Chalk should overwrite the session continue the old session by appending or if the recording should be abandoned returning to the setup for changing the output directory Following that the setup dialog is hidden and the different recording com ponents board
87. tools 110n GrepTxtCall usage gt java echalk tools 110n GrepTxtCall h kI 1 s pl 0 nw v r lt file gt h Print this message and exit k Plain listing of all L10N keys in order of appearance default l List with filename and line number for each key s List sorted keys with duplicated removed p Sorted property output for default identity mapping 0 No output of keys Useful for getting just the warnings m Search for mnemonics keys instead of text keys nw Nowarn do not report non literal keys v Verbose output Only used for s and p modes r Recursively search all dir files for java files gt java echalk tools 110n KeyCmp usage gt java echalk tools 110n KeyCmp lt propfilei gt lt propfile2a gt lt propfile2b gt gt Listing 3 7 Usage of command line utilities for the internationalization of the system them Because the GrepTxtCall performs only a static analysis of the Java source code it cannot evaluate variables or method calls as keys and prints warnings if it encounters such keys To be able to use this tool the source code of E Chalk uses only literal strings and strings composed of concatenated literal strings 2 The command line options of GrepTxtCall allow to directly output a property file usable as a resource bundle for the English localization using the identity mapping between keys and entries It handles any special encoding needed for the property file for example spaces
88. using the Java Media Framework JMF The screen image is transmitted using VNC s Remote Framebuffer Pro tocol RFB For supporting multicast TTT modified the protocol to use UDP instead of TCP To compensate for UDP not offering reliable transmissions TTT added information transmitted for redundancy in critical updates Band width requirements are about 50 60 kbps for audio an average of 50 60 kbps for the screen with peaks estimated to be twice as high and the optional video ranging from hundreds to over 1 000 kbps depending on the video stream qual ity In the recorded lecture the video is stored in QuickTime format using the H 263 Zhu97 BCD 98 codec the audio is stored as u law mono The VNC screen stream is directly stored as it is transmitted Examples can be found at 95 23In ZS02 the authors report difficulties with handling the audio recording and the trans mission on the same computer As a workaround they use different servers for the two tasks of archiving and live transmission 22 CHAPTER 1 INTRODUCTION AND RELATED WORK Untitled FXPAL NoteLook olx Ei dit View Properties Options Help Debug F Auto Snap EM TE Feb03 99 Page3of5 x os eksas rl ol Performance Steady growth Excellent dd Optimistic forecast next year H Notebook Figure 1 14 The NoteLook client for synchronous access Figure from CKRW99 The client for both liv
89. were interviewed by the evaluator and asked their opinions on and experiences with E Chalk An overview of the survey data gathered is given in Table 8 2 Findings In the TU Berlin courses the printable PDF was preferred to replay of lectures by most students The low popularity of the replay hardly came as a surprise as no audio signal was recorded at TU Berlin Students at FU Berlin used the PDF and the replay on an equivalent level According to the statements on the amount of remote use the remote ac cesses intensified in Introduction to Numerics and Neural Networks or re mained at a constant level all other courses during the term This result is supported by access statistics from the Neural Networks lecture see for ex ample Figure 8 7 The rising intensity probably indicates students preparation for upcoming exams However no significant correlation between exam results and E Chalk use could be found In all user categories almost the same grade has been achieved compare Figure 8 8 The report suggests further examination by forming two groups with the same external conditions differing only in the use of E Chalk Adopting E Chalk in teaching did reveal neither positive nor negative effects on the students motivation to prepare for the lecture The quality of the soft ware was judged positively by the students Didactic quality of the courses was perceived well compared to regular courses see Figure 8 9 5 Students wel
90. www moses tu berlin de Mathematik LineareAlgebra WS_2003_2004 L1 Echalk linaseil_2004 01 26 Smart Technologies Inc http www smarttech com SumTotal Systems Inc ToolBook Authoring Products http www sumtotalsystems com toolbook SWISHzone com Pty Ltd http www swishzone com TeamBoard http www teamboard com TechSmith Corporation http www techsmith de Tegrity http www tegrity com Tele TASK Tele Teaching Anywhere Solution Kit http www tele task de TeleTeaching Universit t Trier http teleteaching uni trier de WEB REFERENCES 197 96 Christian Thomsen Physik f r Ingenieure Optik E Chalk recording 97 98 99 100 101 102 103 104 105 106 107 108 109 110 winter term 2003 04 http www physik tu berlin de institute IFFP moses ekreide physing_2004 01 28 Christian Thomsen Physik f r Ingenieure Thermodynamik 1 E Chalk recording winter term 2003 04 http www physik tu berlin de institute IFFP moses ekreide physing_2004 02 04 Fredi Troeltzsch Analysis II Oberfl chenintegrale E Chalk recording summer term 2003 http www moses tu berlin de Mathematik Analysis2 SS_2003 B1 Echalk ana2_troeltz_2003 07 04 Fredi Troeltzsch Analysis II Satz von Stokes E Chalk recording summer term 2003 http www moses tu berlin de Mathematik Analysis2 SS_2003 B1 Echalk ana2_troeltz_2003 07 11 Unisys LZW Patent Informati
91. 0 Asheville NC USA Novem ber 1999 ACM press Ernesto Tapia Understanding Mathematics A System for the Recognition of On Line Handwritten Mathematical Expressions PhD thesis Fachbereich Mathematik und Informatik Freie Uni versitat Berlin December 2004 Larry Tesler The Smalltalk environment BYTE 6 8 90 147 August 1981 Florian Theimer Automatische Handschriftenerkennung in E Kreide Dokumenten Technical Report B 04 05 Fachbereich Mathematik und Informatik Freie Universitat Berlin 2004 Florian Theimer Automatische Handschriftenerkennung in E Kreide Dokumenten Bachelor s thesis Fachbereich Mathematik und Informatik Freie Universitat Berlin April 2004 Ernesto Tapia and Ratil Rojas Recognition of handwritten digits in the E Chalk system using support vector machines Technical Report B 02 14 Fachbereich Mathematik und Informatik Freie Universitat Berlin 2002 Ernesto Tapia and Ratil Rojas Recognition of on line handwritten mathematical formulas in the E Chalk system In Proceedings of the Seventh International Conference on Document Analysis and Recognition ICDAR volume 2 pages 980 984 Edinburgh UK August 2003 IEEE Computer Society 188 TROA Tsi99 Tuf03a Tuf03b Vap98 VN94 vRD03 W3C98 W3C01 Wat04 WBM00 Wei93 Wel83 Wel84 BIBLIOGRAPHY Ernesto Tapia and Ra l Rojas Recognition of on line handwrit ten mathematical expressions usin
92. 14 Students opinions on the system s impact on the organization of their study About half of the students 46 8 reported using the E Chalk materials regularly for revising the classes The average time spent revising including the zero minutes users was 19 minutes per week Considering only those students who actually use E Chalk for revision the average was 40 minutes the median 30 minutes However these figures should not be taken to literally as they display a high degree of variance See Figure 8 12 for details When asked for the type of E Chalk material mainly used for revision most students preferred the PDF over the replay especially TU students see Figure 8 13 Just as in the evaluation of the previous term replay has been expected beforehand to be unpopular among TU students because the recordings did not include audio The students were asked to judge the impact of the system on their studies whether it helped in or complicated learning The answers showed a clearly significant tendency towards a positive impact The most favorable results were observed for FU seminars where the system was used for interactive teaching see Figure 8 14 These answers were investigated as to a correlation with the preferred use of lecture materials for revision Those students who did not use any E Chalk material at all noticed no significant impact The number of replay preferring users was too low to yield a significant correlati
93. 192 Seattle WA USA November 1996 ACM press J rg Gei ler Shuffle throw or take it working efficiently with an interactive wall In Clare Marie Karat Arnold Lund Jo lle Coutaz and John Karat editors Proceedings of the Conference on Human Factors in Computing Systems CHI pages 265 266 Los Angeles CA USA April 1998 ACM press Erich Gamma Richard Helm Ralph Johnson and John Vlissides Design Patterns Elements of Reusable Object Oriented Software Addison Wesley 1995 David Goldberg and Catherine McCartin Touch typing with a stylus In Proceedings of the conference on Human factors in computing systems INTERCHI pages 80 87 Amsterdam The Netherlands April 1993 ACM press James Gosling and Henry McGilton The Java Language Environ ment Sun Microsystems May 1996 White Paper Francois Guimbreti re Andrew Martin and Terry Winograd Measuring FlowMenu performance Technical Report CS TR 2001 02 Stanford University Department of Computer Science September 2001 David Goldberg United States Patent No 5 596 656 Unistrokes for computerized interpretation of handwriting 1997 Xerox Cor poration filed October 26 1995 Ruled invalid due to prior art by Judge Michael A Telesca of the United States District Court for the Western District of New York on May 21 2004 Francois Guimbretiere Maureen Stone and Terry Winograd Fluid interaction with high resolution wall size displays In Pro ceedings
94. 192x1 44x5 board Starting in on demand mode board Audio OK Syncing entri Hello to E Chalk Board entri Hello to WWR2 entri Hello to WWW entri Ready L schen Kopieren schlie en Figure 7 6 Standard client messages for debugging purposes written to the Java console of the browser Applet is usually only allowed to connect to the host its code is loaded from As a consequence this parameter is only used when starting the client from a local HTML file For this the Java appletviewer and some browsers allow to loosen the security restrictions to connect to the local host When the Applet is loaded from a remote connection the server location of the Applet s code base entry is used instead When the Applet is loaded locally the server parameter is used instead or if it is not set its default value of 127 0 0 1 is used e baseurl This parameter is used as the root location for all board data to be loaded the events data file board events the image data files images no dat and the Applet HTML files applets no html It is given as a relative path to the code base URL of the Applet and defaults to the code base Because of the security restrictions of Applets it has to be the code base itself or a subdirectory The parameter is used for debugging purposes only e debug The board client writes certain status messages to the browser s Java text console See Figure 7 6 for
95. 4 Its supports interaction types of a Python programming environment interface to be used during a lecture It accepts handwritten Python commands that are then rec ognized by the chalklet Recognized lines can be combined and reordered into a Python script by drag like pen drawings Recognized writing can also be inserted at arbitrary program positions again by a drag like gesture and recog nized letters can be deleted by a strike through As a fallback input possibility the chalklet provides a keyboard like input It shows all letters and takes any letters stroked out as input The scripts can be run using the Jython 48 inter preter a Python implementation in Java A running script can be stopped by the lecturer allowing to exit from programs with long runtimes or with infinite loops As scripts and program output can be too long to fit in their chalklet areas horizontal and vertical scrolling by horizontal and vertical pen strokes is supported 23For a short introduction to usability laboratory tests see Shn98 6 13 POST PRODUCTION WITH EXYMEN 123 i in range n s txr j 1 Figure 6 16 Python interpreter chalklet At the top the program window at the bottom an area used for both handwriting input by the user and program output for running Python scripts Image courtesy of Henrik Steffien The handwriting mechanism uses the Microsoft Tablet PC recognizer To avoid having to run E Chalk on Windows XP Ta
96. 7 Import of PowerPoint Presentations With the abundance of material already produced as PowerPoint presentations there is considerable demand to import this material into other lecturing tools The eClass system includes the TransferMation tool for automatically con verting PowerPoint presentations to images and importing them into eClass 17Note that damaged board events in unrepaired lectures do not prevent the recording from being used for replay or append mode as the board event interpreter just skips unrecognized events with logging a warning to its error stream unless the option to abort on invalid events is explicitly set The same holds true for the PDF converter and for the events interpreter used by Exymen 18For a description of eClass see Section 1 8 5 6 8 KEYWORDS FROM HANDWRITING RECOGNITION 115 sessions Written as a wizard interface in Visual Basic it runs only on Win dows98 Bro01 Another example is the ppt2aof 1 add on for PowerPoint which enables PowerPoint to export the presentation to the format used by the AOF tool AOFwb a wb index file and GIF images of the individual slides For E Chalk a program originally developed as a student s project will convert Microsoft PowerPoint presentations into E Chalk board macros The ppt2echalk converter is a Windows command line executable written in Del phi relying on the MS PowerPoint automation API to convert the presentation s slides into image files
97. 90 Tom Creed PowerPoint no Cyberspace yes The National Teach ing amp Learning Forum NTFL 6 4 1 4 1997 Robert Carr and Dan Shafer The Power of PenPoint Addison Wesley Reading MA USA February 1991 Kam Fai Chan and Dit Yan Yeung Mathematical expression recognition a survey International Journal on Document Analy sis and Recognition IJDAR 3 1 3 15 2000 Roger B Dannenberg and Peter Capell Are just in time lectures effective at teaching Technical report Carnegie Mellon Univer sity School of Computer Science Pittsburgh PA USA June 1997 BIBLIOGRAPHY 173 DC01 Deu96 DG96 Dic97 Die98 Die03 DLC 99 DSAO1 EGE97 EILM00 EPT 92 Andrew Deitsch and David Czarnecki Java Internationalization chapter 4 pages 67 75 O Reilly March 2001 L Peter Deutsch RFC 1951 DEFLATE Compressed Data For mat Specification version 1 3 IETF TESG May 1996 L Peter Deutsch and Jean Loup Gallier RFC 1950 ZLIB Com pressed Data Format Specification version 3 3 IETF TESG May 1996 Michael Dickreiter Handbuch der Tonstudiotechnik volume 1 K G Saur Munich Germany sixth edition 1997 J rg M Diehl Frageb gen zur studentischen Evaluation von Hochschulveranstaltungen Justus Liebig Universit t department of psychology Giessen Germany 1998 Manual und Auswer tungsprogramm zum VBVOR und VBREF Lehrevaluation Sp 6 Michael Diener Lichtpunkterkenn
98. ACM 44 11 November 2001 Elizabeth D Mynatt The writing on the wall In Proceedings of the International Conference on Human Computer Interaction INTERACT pages 196 204 Edinburgh UK August Septemer 1999 IOS Press Jakob Nielsen Designing Web Usability New Rider Publishing Indianapolis IN USA 1999 BIBLIOGRAPHY 183 Nor81 Nor88 Nor98 OSGO02 PCST00 PEO2 Per98 PK99 PKPRO2 Pla99 PMMH93 Ra 00 Donald A Norman Categorization of action slips Psychological Review 88 1 1 15 1981 Donald A Norman The psychology of everyday things Basic Books New York NY USA 1988 Donald A Norman The Invisible Computer Why Good Products Can Fail the Personal Computer Is So Complex and Information Appliances Are the Solution MIT Press Cambridge MA USA 1998 OSGi editor OSGi Service Platform Release 2 IOS Press Ams terdam Netherlands 2002 John C Platt Nello Christiani and John Shawe Taylor Large margin DAGs for multiclass classification Advances in Neural Information Processing Systems 12 547 553 2000 Fernando Pereia and Touradj Ebrahimi editors The MPEG 4 Book Multimedia series Prentice Hall Upper Saddle River NJ USA 2002 Ken Perlin Quikwriting continuous stylus based text entry In Proceedings of the eleventh annual ACM symposium on User in terface software and technology UIST pages 215 216 San Fran cisco CA USA Novemb
99. An Electronic Chalkboard for Classroom and Distance Teaching Dissertation zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften im Fachbereich Mathematik und Informatik der Freien Universitat Berlin vorgelegt von Lars Knipping aus Itzehoe 14 Februar 2005 Gutachter Prof Dr Raul Rojas Prof Dr Ruedi Seiler Preface Quis leget haec Persius Satires 1 2 Many people have contributed to the development of the system being de scribed in this thesis The project was conceived by Prof Dr Raul Rojas who accompanied its development and provided many ideas The first prototype of the board software was written by Wolf Ulrich Raffel The entire audio part is authored by Gerald Friedland on the basis of the WWR system by Gerald Friedland and Tobias Lasser and its successor WWR2 by Gerald Friedland and Bernhard Frotschl Gerald Friedland also designed the multimedia editor called Exymen and the video part of the E Chalk system Kristian Jantz assisted in the video software development He implemented the SID plug in for Exymen the Maple connection for the board and a number of tools one for converting lecture recordings to AVI and QuickTime movies another for generating board snapshots one for updating the audio format and a tool for restoring damaged recordings Ernesto Tapia developed the mathematical handwriting recognition inte grated in the board component Mary Ann Brennan wrote the first versi
100. Arabic Linguistics was delighted to be able to give a chalkboard lecture while seated using a digitizer tablet for himself 12 Before the wheel chair bound professor always had to have a student or assistant to do the blackboard writing for him Another example is a setup at a German high school where the computer room is too cramped for the regular classroom setup There is not enough room for a blackboard and students desks provide just enough space for the computer hardware not leaving enough space for taking notes The teacher uses E Chalk with a small digitizer tablet and projects the board content onto the wall see Figure 8 3 The E Chalk PDF is printed out at the end of the class so that students have access to a written copy of the material covered in class For smaller seminars one can use a setup with several digitizer tablets enabling students to interact with the board contents from their own seats In the case shown in Figure 8 4 the Geology lecturer uses a rear projector and the students use small digitizer tablets to work on geographical maps FU Data Wall At Freie Universitat Berlin a rear projected data wall was built to provide a spacious electronic board hardware FKRT04 see Figure 8 4 The wall display is composed of four screens controlled by a single PC with a multi head graphics card The pen is a laser pointer turned on by being pressed against the screen surface The laser light is tracked by cameras a webcam
101. EMOTE ACCESS 43 21943 Figure 2 15 A macro for showing the Bubble Sort algorithm as animation Figure from Esp04 Macros Another kind of bookmarks that can be used are E Chalk board macros These are simply board recordings that can be replayed on the board After selecting a macro bookmark one has to position the replay by defining the vertical start position see Figure 2 11 Writing and images from the macro are then added to the board with the speed they were originally recorded scaled by a factor defined in the macro bookmark When a new element would be located in a part of the board not visible due to the current vertical scroll offset the offset is adjusted accordingly automatically scrolling the board The macro can be aborted anytime Any edit to the board other than scrolling stops the macro replay Macros can be created like regular lectures with a macro recorder tool or they can be generated synthetically for example for showing animations See Figure 2 15 for an example 2 5 Remote Access One only needs to open the Web page for the lecture in a browser to view the lecture replay The replay client is realized as several Java Applets embedded in the Web page Each of the three possible streams is received by an Applet the board audio and video client For live transmissions these Applets open a TCP socket connection to the lecture server Audio and video clients decode their data streams and output them
102. ESG June 1999 Paul M Fitts The information capacity of the human motor system in controlling the amplitude of movement Journal of Ex perimental Psychology 47 6 381 391 June 1954 Armando Fox Brad Johanson Pat Hanrahan and Terry Wino grad Integrating information appliances into an interactive workspace IEEE Computer Graphics amp Applications 20 3 54 65 May June 2000 Gerald Friedland Kristian Jantz and Lars Knipping Conserving an ancient art of music Making SID tunes editable In Lecture Notes in Computer Science volume 2771 pages 290 296 Springer Verlag Heidelberg Germany May 2004 Gerald Friedland Kristian Jantz and Lars Knipping Towards automatized studioless audio recording A smart lecture recorder Technical Report B 04 14 Fachbereich Mathematik und Infor matik Freie Universitat Berlin September 2004 Gerald Friedland Lars Knipping and Raul Rojas E chalk tech nical description Technical Report B 02 11 Fachbereich Mathe matik und Informatik Freie Universitat Berlin May 2002 BIBLIOGRAPHY 175 FKRO3 FKR 04a FKR 04b FKRTO3 FKRT04 FKST04 FKTO4 FL98 FPOA Gerald Friedland Lars Knipping and Raul Rojas Mapping the classroom into the web Case studies from several institutions In Andr s Sz ks Erwin Wagner and Costas Tsolakidis editors The Quality Dialogue Integrating Cultures in Flexible Distance and eLearning pages 480 485 Rhodes Greece
103. Euclidean distances of all pixels 10From the very beginning of E Chalk the system focussed on transmitting the information by board content and voice stream This philosophy is backed by experiences from other projects the lecturer s voice stream is reported to be the most important information channel for learners BGL96 EGE97 followed by the whiteboard blackboard slide stream MO02 with the video stream of the lecturer mainly being of interest to create a sort of social context 11The current implementation of the WWV server can already produce non E Chalk for mats for example QuickTime video 102 CHAPTER 5 AUDIO AND VIDEO SERVERS Figure 5 9 Semi transparent instructor over board image montage in the YUV color space with the Y component given a higher weight The relevant blocks are encoded in JPEG format Decoding is easily manageable in the Java Applet because the JPEG decoder is available in standard libraries even for older JVMs In the teaching situation recorded for E Chalk purposes where only a small area of the picture has to be updated mainly due to gestures and mimics of the lecturer this very simple compression performs very well The compression ratio obtained in experiments is roughly 40 1 In recordings with the E Chalk system a video resolution of 192x144 quarter NTSC and 4 frames per second was the standard setup to obtain a bandwidth of 64 kbps 5 4 Video and Board Image Combined E Chalk
104. Figure 1 11 shows a snapshot from a purely hand drawn AudioGraph lec ture using a Java Applet for playback The replay of more recent versions of AudioGraph lectures requires a custom browser plug in to be installed available for Macintosh and Windows PC browsers 1 7 Presentation and Classroom Enhancement This section describes systems to assist lecturing in the classroom and tools for live transmission of classes which do not aim at recording the experience A common approach for lecturers who want to transmit a class is to use a video conferencing solution However video conferencing systems have not explicitly been created for teaching Their conception assumes symmetric com munication and relies on all participants to have equivalent hardware Great effort is spent transmitting audio and video but support for the transmission of teaching specific content such as board drawings is lacking Using standard video compression approaches they exhibit the quality problems discussed in Section 1 1 The most prominent presentation tool is PowerPoint which has been al ready discussed in Section 1 1 Demands to augment slide shows by freehand annotations were often expressed to make the talks more flexible than it is the case when using prepared slides only To this end several research systems had been devised and by now Microsoft has added some annotations functionality to PowerPoint 22 The Office XP for Tablet PC Tablet Pack add
105. ITION 79 9 01284569880 geil un Delta partial lt gt arrow oe lt E a a d b a c e I m r x y zi vneta end a be de 1 mb yO E Figure 4 12 Recognized symbols 4 8 2 Handwriting Recognized Strokes If the handwriting recognition is activated it gets the stroke events from listen ing to the StrokeSender like chalklets do The main difference is that its stroke receiver tags all strokes as relevant which have the color which is associated with the recognition see board settings description in Section 2 4 1 The results of the handwriting recognition are requests to an Evaluator see above An overview of the included handwriting recognizer is given in the following section 4 9 Mathematical Handwriting Recognition The first on line handwriting recognition developed for the E Chalk system used a k nearest neighbor classification The sequence of strokes was grouped into symbols based on intersections of their bounding boxes and a constraint that symbols can be only formed by one or two strokes The recognizer returned its result once a special end symbol was recognized The approach worked quite well for simple calculator type terms However the classification performance decreased dramatically once a greater number of symbols were introduced and it was not capable to handle spatial relationships between the mathematical symbols which are fundamental to the interpretation of more complex formulas For this reason the c
106. K Figure 1 5 Writing the word finished with a single stroke using Cirrin Figure from MA98 Apple Newton MessagePad App93 used writing on sheets of paper as a met aphor The interface of the PenPoint OS CS91 was based on a notebook metaphor and the use of the pen as the primary and for most uses only input device It was a product of the Go Corporation the earliest operating systems written specifically for graphical tablets and personal digital assistants running for example on the Momenta and AT amp T s EO Personal Communicator For creating text input with a pen or mouse a number of approaches have been devised The simplest approach is the use of a software keyboard SRS 93 like the one provided on Windows platforms Handwriting recognition is another popular approach i e the CalliGrapher 74 recognition engine by Paragraph International was integrated in the Apple Newton and the recent version is part of the Windows CE and XP Tablet editions The Xerox Unistroke Recognizer G0197 GM93 is a gesture based system loosely based on the Roman alphabet using a single stroke per letter A similar system is the PalmPilot 72 OS s Grafitti To submit commands with pens context menus with a dial instead of a linear arrangement are often used These pie menus Hop91 allow the user to learn the command selections in a kind of stroke gestures On the downside they are hard to extend when new commands are added and fo
107. KitSetupInfo ParamInfo itself is an abstract class with the available concrete subclasses defining the type of the parameter Allowed parameter types are strings strings without line breaks passwords files booleans enumerations list of possible choices and whole numbers for a declared interval up to the long integer range Each ParamInfo instance defines a parameter name and may give a description and a default value with all texts being localized For example the echalk util cserver MathematicaKit needs the path of the Mathematica kernel file as a parameter ParamInfo objects for files may also provide a customized file chooser using appropriate file filters to help with file selection When the user selects to configure an EvaluatorKit a dialog automatically generated from the KitSetupInfo is shown with input fields adequate for the type of parameter check boxes are used for boolean parameters combo boxes for enumeration parameters text areas and text fields for strings depending on whether these are allowed to contain line breaks password input fields for password strings text fields with file choosers for file parameters and number spinner objects for whole numbers See Figure 3 1 for an example 12For convenience the Mathematica kit provides an intelligent default value by scanning the file system s standard installation paths of Mathematica for a kernel executable preferring the most recent version if several installa
108. L data into the Applet resource directory to make it accessible to E Chalk clients see Section 7 2 4 the referenced Applets are loaded using a custom class loader 16For data returned from an HTTP request the encoding may be specified in the Content type header field If unspecified it defaults to iso 8859 1 ISO Latin1 FGM 99 17See Section 4 11 2 76 CHAPTER 4 BOARD SERVER Lars Knipping s Hone Pager photo Lars Knipping 000 Lars Knippi ngs nnine Freie Universitat Berlin Institut f r Informatik Takustra e 9 0 14195 Berlin Room 147 ist floor Fon 449 0 30 838 75 149 Fax 449 0 30 838 75 193 email knipping inf fu berlin de horizontal bar Pp rojeceston o Electronic Chalkboard o Robocup o Map Labeling o Estima Ratio www Publicati ons eH o Helmut Alt Lars Knipping Gerald Weber an Application of Point Pattern Matching in Astronautics Technical Report B 93 16 FU Berlin Institut f r Informatik November 1993 Downloadable as Gzipped PostScript 216 kB o Gerald Weber Lars Knipping Helmut Alt an Application of Point Pattern Matching in Astronautics Journal of Symbolic Computation 17 4 pp 321 340 April 1994 Downloadable as Gzipped PostScript 193 KB o Lars Knipping Beschriftung von Linienz gen Figure 4 10 The author s home page converted to plain text on the board only top section of converted page shown and initial
109. SBM99 with y 0 001 Experimental Classification Results Experimental data were obtained by having a volunteer writing 50 samples of each of the symbols shown in Figure 4 12 with a Wacom Graphire 2 tablet The number of symbols was then artificially increased ten times by means of transformations related to the tangent distance SM96 The data were ran domly split into three sets 50 of the samples were used for training 25 for testing and the remaining 25 for validation For comparison an Artificial 23 n the current implementation 16 points are taken 24Smoothing is done using the Kernel 0 25 0 5 0 25 25The angles are represented as their sine and cosine values 26 Again the difference angles are represented as their sine and cosine values 4 9 MATHEMATICAL HANDWRITING RECOGNITION 81 support error classifier type strokes vectors train test validate Support Vector Machines 1 29 65 0 31 0 93 0 76 0 72 1 17 1 27 36 73 0 00 0 62 0 70 0 69 1 31 2 09 39 41 0 00 0 00 1 17 0 00 1 17 1 17 Artificial Neural Networks Support Vector Machines Artificial Neural Networks Support Vector Machines Artificial Neural Networks w wI IN N e Table 4 1 Experimental classification rates for Support Vector Machines and Artificial Neural Networks with classifiers built for symbols composed of one two or three strokes The column supp
110. Scrollbar 6 5340 Scrollbar 16 54a5 Scrollbar 13c 6567 Form Text 42 19e ff00ff00 c 6e0c Text SetTxt plot t sin t t Pi Pi 7406 Text End plot t sin t t Pi Pi 83b6 Form Image 0 3e 1a8 908a Undo Essa Listing 4 2 Excerpt from a board event file below Nop Scroll Clear All Undo Redo Terminate The simplest event is NOP having no mandatory parameters timestamp Nop plain ascii text The board creates these at the start and end of a recording as commentary entries date and time are stored as a commentary token as well as the creation mode created or appended See Listing 4 2 for an example The events for clearing the whole board for undo and redo also do not need any parameters and scrolling events use the single parameter scrolloffset the new vertical offset of the board s top position timestamp RemoveAll timestamp Undo timestamp Redo timestamp Scrollbar scrolloffset The terminate event is exclusively used in live transmissions to signal to a client the end of transmission see Section 4 12 timestamp Terminate 4 11 EVENT STORAGE 89 Line Segments A line segment from point xo yo to point x1 y1 drawn with stroke radius r in color c has the form timestamp Form Line xo yo x y1 r c with all numbers given in hexadecimal Again see Listing 4 2 for an example Images An image added to the board with x y being the position of the upper left corner is represented as t
111. TION AND RELATED WORK Figure 1 4 E Chalk with a plasma screen display here in combination with a digitizer tablet Wacom Intuos 103 as input device not become popular before the Windows Tablet PCs released in late 2002 When hardware mobility is not an important factor the instructor should ideally be enabled to write directly on the shared screen This way learners do not have to look back and forth between the talking teacher and the screen as both are in the same place For this technologies for pen writing on wall displays are required Display technologies of such solutions usually use front or rear projection In early E Chalk experiments plasma screens with touch technology were also tested Raf00 RKRF00 RKFF01 but the susceptibility of these screens to burn in effects made them an inapt choice See Figure 1 4 for an example usage A front projected solution is much cheaper than a rear projection system and easier to move as rear projection systems tend to be quite heavy However the projection of the latter is superior in brilliance is less susceptible to interference from sunlight and the instructor also does not cast shadows when he or she stands in front of the display With front projection the instructor might look into the glaring projector when turning to the audience Moving the board changes the relation between position on the board and in the displayed image and requires recalibration of the system In the
112. The E Chalk system defines its own java io PrintStream class for message streams Its constructor allows to specify a label to prepend to each output line The system uses this to mark output by the component it came from the board component s output starts with board the PDF converters output with pdf output from the main control with echalk etc With the stream inheriting from PrintStream and handling the tagging of a line start internally it can also be used for printing tagged exception stack traces by calling the printStackTrace PrintStream ps method ofa java lang Throwable With the default settings for the E Chalk configuration the stream output is sent to the system s standard output stream the command line console if it was activated and to a log file by default named conf echalk 1og The E Chalk components use two output streams one being the tagged standard output stream and another for debugging purposes When the system is started with the echalk debug property set to true the debug stream is set to the standard output stream Otherwise it is set to a dev null like stream ignoring all output calls Chapter 4 Board Server 4 1 Painting on the Board The code for displaying content on the board is shared between the client and the server side board for maintenance reasons With the client Applet required to run in a browser supporting only Java 1 1 this shared code cannot use more recent Java library additio
113. The sound card is graded using back 3On notebook computers this is not always possible because built in microphones cannot always be switched off The wizard then adjusts its analysis process 4In English repeating the word coffeepot gives good results 5The filters applied are described in Section 5 2 4 6This might be assisted by supplying equalizer presets for different pitches of voice like bass and tenor and by automatically preselecting the preset fits best 5 2 SMART AUDIO RECORDING 99 1 sec gt gt lt e gt speech cough pause speech Figure 5 6 Without above and with below mixer control The speech signal is expanded and the cough is leveled out ground noise and the card s DC offset is calculated from the recordings Grad ing the equipment is based on background noise recordings and frequency shape This is only a rough grading assisting non expert users to judge the equipment and identify quality bottlenecks Further testing would require the user to work with loop back cables frequency generators and or measurement instruments Among other information the created profile contains all mixer settings the equalizer settings the recording and the sound card s identification 5 2 4 During Recording For recording the system relies on the equipment profile If changes are de tected for example a different sound card the system will display a warning at start up Figure 5 5 illustr
114. This means the converter program needs PowerPoint to be installed on the system and running the converter starts PowerPoint though the application is partially hidden since as it runs in iconified mode The resulting macro adds the slides one after another to the board from top to bottom Depending on the converter s command line options the macro contains scroll events to change from one slide to the next usage gt ppt2echalk lt ts gt lt ts gt lt lecture dir gt lt out dir gt When called without any options all the slides are added to the board im mediately and the macro ends allowing to scroll the slides at the user s own pace When a number lt ts gt is given it denotes the time in seconds that the macro pauses between slide images before the next slide is added and a scroll event is issued to move to the new slide image simulating a slide show with automated transitions When the number is given in brackets it will only be used on those slides for which the presentation does not define its own transition time The board width the macro will produce is determined by the width of the output slide images The converter provides no option to choose this size as the PowerPoint automation API does not currently allow to change the image dimensions To provide control over the macro s dimension the slide images would need to be scaled by the converter program a feature that has not been implemented so far 6 8 Keywor
115. This way all of it can be compressed together instead of compressing several chunks individually 6 1 2 Images Accessing pixel data by the Java image rendering mechanism is used as a generic method for getting the PDF representation of an image included in a board lecture The image file is loaded as a java awt Image and a java awt im age PixelGrabber is applied The converter then tries to get a more compact representation of these data If the image contains 256 colors or less a color lookup table is used The image data are compressed using flate if this reduces the amount of data If a color table exists it is also flate encoded Transparent color can also be handled in the PDF converter as PDF allows to mark color entries as transparent Semi transparency a feature supported by PNG files cannot be represented in current PDF versions Even full transparency is not supported by all printer drivers For example on PostScript printers PostScript level 3 must be supported for transparency being available For GIF and JPEG data the converter uses faster methods by directly parsing these formats Still the pixel grabbing method serves to handle other formats and as a fall back for example for damaged JPEG files see below At the time being the only image format used in E Chalk recordings that is not directly parsed is PNG 1 JPEG Parsing The encoded image data from JPEG images can be directly included in a PDF image object as the
116. Wilma Rudolph Oberschule in Berlin Center A young visitor of the Chemistry de partment of the Deutsches Museum in Munich describing his favorite experiment with E Chalk Right The artist Kiddy Cidny streaming a live art performance into the Web how to operate the software anyway whether the visitor is a young child or an older person The only feature reported not to be obvious to uninitiated users are the drag handles On the other hand once demonstrated the feedback on the drag handles was always positive Pathologists at the Klinik am Eichert hospital in G ppingen Germany plan to adopt E Chalk combined with a video conferencing system for ad hoc com munication about diagnostic findings with physicians in other places The system was even used in an art event The Himmel5 art show 34 organized a performance streamed live into the Web see Figure 8 1 8 1 1 Hardware Setup in the Lecture Room When using the E Chalk software in classroom teaching one needs a pen based input device and a large display for the audience Ideally the display itself is the writing surface increasing the similarity to the chalkboard usage This can be realized by using digital whiteboards or rear projection systems with pen tracking The whiteboard systems are basically wide perpendicular mounted digitizing tablets with a diagonal of up to 80 inches The screen content is dis played by an LCD projector see for example Figure 8 2 This front projec
117. activate the Microphone Monitor during recording showing a warning dialog when the microphone signal is lost usually due to batteries running low in a wireless microphone To help for remembering which profile belongs to which configuration one can select to display the properties of the profile Information about the date the profile was created and the hardware setup are shown in addition to the equalizer settings and the audio wizard s summary report see Figure 2 6 Video Settings In the settings for the video stream the user can choose the video source to capture and the resolution and the frame rate to be used Resolution and frame rate have to be chosen with care with regard to the bandwidth they will consume During the installation process E Chalk scans for available video sources As this process takes several seconds it is not done every time E Chalk is started However the video settings page allows to trigger the scan process manually to make newly installed video sources known to the system See Figure 2 7 for a snapshot of the video settings page Live Settings In the live settings page a maximum number of live connections can be defined depending on the server s performance The TCP server ports the streams are sent over can be redefined This is only important if the default ports are already occupied on the server or if their use is disallowed by a firewall 16 A planned extension to the setup dialog is
118. ake directories list processes launchables started request programm shutdown resume thread lt no gt remove directories dump console content to lt file gt exit w o saving dangerous list set system properties set priority lt pri gt to thread lt no gt execute commands from file s list set echalk settings suspend thread lt no gt list threads stop thread lt no gt remove an alias remove system property show echalk version info Listing 3 8 Log from the command line console List of available commands 62 CHAPTER 3 THE E CHALK APPLICATION uncomment to start memory monitor tool on console startup launch echalk tools debug MemoryMonitor amp alias definitions alias help alias exec alias print echo alias alloc free alias kill deorbit alias whoami set user name alias uname set os name alias arch set os architecture alias pwd set user dir alias la ls aF alias 11 ls alhF alias edit launch echalk util TextEdit alias topdf launch echalk tools pdf Board2PDF alias browse launch echalk util HtmlViewer alias showmem launch echalk tools debug MemoryMonitor print welcome message echo E Chalk command line console Enter for help Listing 3 9 Example console rc file See Listing 3 9 for an example startup file The Interfaces Launchable and Progressible Several parts of the E Chalk system are loaded and started dynamically see Section 3 1 1 Their names and the parameters
119. aled and translated to get a normal ize size and position for the bounding box of all strokes belonging to a single symbol The feature vector used as input for the classifier is constructed from a num ber of local and global features The local features for a stroke of length formed by the preprocessed points p1 Pn are the coordinates of the points p the turning angle between the two consecutive segments p _1 pi and pi pi 1 the points relative length position defined as 4 Ny px Pr 111 for the point p and the change of the turning angle for two consecutive turning angles Global stroke features represented in the input vector are the center of gravity of the stroke points the length of the stroke the relative stroke length d where d is the distant between the first and last point of the stroke and the accumulated angle i e the sum of all turning angles The SVM classifier Three classifiers are used depending of the number of strokes that form the symbol For symbols that there composed of more than one stroke the feature vector of each stroke is constructed and the concatenation of the feature vectors content forms the full input vector which represents the symbol The classifier implementation uses DAG SVMs PCST00 as a multi class SVM classifier with an RBF kernel for all the classification nodes and the first modification of the Sequential Minimal Optimization SMO algorithm from Pla99 K
120. already annotated by the lecturer Requests to Computer Algebra Systems Mathematical requests can be processed by the board using an interface to computer algebra systems such as Mathematica by Wolfram Research Wol03 108 or Maple by Waterloo Maple MGH 97 105 22 When such a system is installed the corresponding button allows to type a request exactly like normal text typings are done On closing the text input with the enter key the request is sent to the algebra system and evaluated If the system returns a graphic it can be pasted to the board in the same interaction style that other images are positioned Otherwise any textual result is typed below the request string See Figure 2 12 for an example of a plotting request evaluated with Mathematica Requests to CGIs The board also allows to make calls to Web services as bookmarked CGI scripts When a CGI bookmark is picked from the CGI bookmarks the user positions a text cursor on the board For each of the CGI parameters defined in the bookmark the user is prompted for a value 2 The CGI is then called and a text or image result is added to the board like for requests to computer algebra systems See Figure 2 13 for examples Mathematical Handwriting Recognition As mentioned before keyboard typing in the pen based E Chalk interface are an interruption of the workflow Keyboard inputs should be replaced by pen inputs when working in the board metaphor For this reason a
121. ame time the lecture is being saved and transmitted live over the Internet without extra effort required of the instructor The system transmits audio video and the animated board image of the lecture A PDF file is also generated as a static copy of the board content for printing The goal is to preserve the didactic advantages and the easy handling of the traditional chalkboard while augmenting the classroom 9This is a problem that is not specific to the e learning domain As argued by Donald Norman the prevalence of PCs result in most information technologies being technology centered instead of being human centered Nor98 10Quote cited according to And04 6 CHAPTER 1 INTRODUCTION AND RELATED WORK Figure 1 2 The idea of E Chalk represented as an E Chalk sketch teaching and extending its reach to distance learning See Figure 1 2 for an overview sketch of the system In order to take advantage of the lecturers already being proficient in chalk board lecturing the tool to be developed should closely resemble the chalkboard in handling and avoid burdening the user with technical details as far as pos sible Integrating the system in a non interfering way into the users everyday environment does not only ease the handling of the system it is also essential for the system s widespread acceptance As BAT99 noted our experience is that even for scheduled activities like classes users are reluctant to spe
122. and independent of the other board objects EILM00 The system was implemented in Java 19 Flatland uses the variant of pie menus with the homing strategy for uninterrupted input sequences See Section 1 4 for a short description of pie menus 14 CHAPTER 1 INTRODUCTION AND RELATED WORK Figure 1 8 Left Several Flatland segments with different behaviors applied to them Right Adding a single stroke to a segment with the map behavior Figures from ELMO0 1 5 5 i LAND and FLUIDUM The Fraunhofer i LAND SGH98 project is inspired by augmented reality and Ubiquitous Computing Computer augmented roomware is created by inte grating computer based information devices into parts of a room e g furniture doors walls and to form co operative environments rooms and buildings The project tries to create the workspaces of the future SGH 99 as an interactive landscape for creativity and innovation for example group work and informal meetings where participants are at different locations The controlling beach software is written in Smalltalk STMTKO1 Apart from a mechanism for establishing relations between physical objects and information objects called the Passage mechanism the project created an interactive table called Interac Table computer enhanced mobile and net worked chairs called CommChair and an interactive electronic wall called Dy naWall This is a 4 5x1 1m back projection wall with a resolution of
123. and are deleted with background colored repaints by the chalklet 6 12 2 Animated Algorithms A number of animated sorting and graph algorithms have been realized as chalk lets Esp04 see for example Figure 6 13 They aim at visualizing algorithms in computer science teaching These chalklets take user strokes as handdrawn in put to the algorithm e g a collection of strokes to sort according to their height or handdrawn graphs using the lengths of the connecting edges as weights Esp04 also presents an engine called Flashdance that produces algorithm animation in Flash from pseudocode input and provides a framework for gener ating E Chalk macros via Flashdance The algorithm uses handdrawn strokes from an E Chalk recording as input The event file with the strokes and the definition of the algorithm are fed into an animation generator producing a 6 12 EXAMPLE CHALKLETS 121 Figure 6 14 Two snapshots from the Neural Networks simulating chalklet Im ages courtesy of Olga Krupina Flashdance script that is then converted to an E Chalk macro This allows to generate macros showing animated algorithms Unlike the chalklets described above these animation macros are not interactive on the board and their oper ations have to be generated in advance to the teaching However in Wat04 an approach is researched to extend the Flashdance engine to produce chalklets 6 12 3 Simulation of Neural Networks A solution for simulating bi
124. anel scans for all Masi Applets started in the same Web page and allows the user to access any controls that are simultaneously provided by all Masi instances In the E Chalk client Applets all capabilities for navigation in time are supported pausing setting forward and backward offsets rewind and jumping to random offsets The control panel displays the time reported by the Masi Applets if the Applets local times differ the control panel uses the maximum time value with both a slider and a text display Clicking on the time display toggles the display modes of elapsed time remaining time and total time The control panel displays a warning text at the bottom and changes the mouse cursor to a wait cursor whenever the Masi instances are stalled for example when they do not get their data fast enough on a forwarding action When a Masi instance reports permanent errors by its method boolean hasPermanentErrors or if it is no longer active determined by the Applet method boolean isActive it is removed by the control panel from the list of controlled Applets When no Applet remains to be controlled the control panel closes Except for navigation by chapters which is defined in Masi but currently supported neither by the control panel nor by the replay Applets 3A possible improvement would be a capability to play at higher speeds 7 1 CLIENT CONTROL PANEL AND MASI INTERFACE 131 i Web server i i s
125. are not hard coded but defined in the startup configuration files as properties The loading process relies on the components implementing the de echalk util Launchable interface and such Launchables can also be loaded and started from the command line console using the launch command Examples for Launchables in E Chalk are the components for the streams to record board audio and or video Further examples are the audio profile wizard the board to PDF converter the html browser used for the help system and the text editor used to edit the configuration files in the expert mode setup The Launchable interface specifies three methods a void init String method a void launch method and a void deorbit method The init method initializes the components with component specific arguments The launch method actually starts the recording process without further delay The two phases are separated to establish a synchronization point when used to start E Chalk s different stream recording components see Section 3 6 The launch method is expected to block the thread it was called from until the Launchable s process is terminated or until it is stopped externally by calling the deorbit 31 For example the PDF converter does not respond until the conversion process from board data to a PDF file is finished 3 10 DEBUGGING TOOLS 63 Sl Memory Monitor Sampling rate 30ms sample max 9 660kB blue total red used
126. as made on courses using electronic slide presentations like MS PowerPoint traditional chalkboard teach ing and overhead slides E Chalk was favored above all these three teaching media with PowerPoint coming closest and overhead slides ranging last see Figure 8 18 Finally the students were asked to give commentaries on three categories on the advantages of the E Chalk system on its disadvantages and on suggestions for improvements The most often repeated advantages include praising remarks on the appearance and organization of the board content 79 times remarks on revision opportunities 71 times that is is no longer necessary to copy the board content 33 times the improved visualization by using images and or Applets 28 times the possibility of remote access 22 times and the learners having more time and concentration to follow the lecture 20 times Further remarks made at least five times were that it is no longer necessary to wipe the board 19 times and an improved adaption of the instructors speed to the audience 7 times Among the facts mentioned more than once users remarked that one can scroll back to previously written content the spontaneous and interactive development of the classes and an increased motivation of the learners 12Note that teaching with E Chalk might have an impact on teachers speech intelligibility For example using a microphone might change the lecturer s speaking style See al
127. asses 2 2 222200 47 3 1 2 Multiuser Configuration 2 2 2 2222 47 3 2 Data Model of the Settings o nen 47 3 3 Connecting Computer Algebra Systems 48 3 4 BookmarkPiles 009 A DAA AAA 50 3 5 Audio Profiles Teddi 2 a ape ee ee ae sd 51 3 6 Starting a Lecture Recording o 52 3 7 HTML Templates 2 2 2222 Eon 54 3 8 Help Systems u GD Se nenne era el 56 3 9 Localization es an A ae gt ds 56 3 10 Debugging Tools o nn 59 3 10 1 E Chalk Command Line Console 59 3 10 2 Message Logging 2 22 Cm nn 64 Board Server 65 4 1 Painting onthe Board nn 65 4 2 Drawing Lines ansehen 66 did Ly pins Westies i see TI BD 67 4 4 Images and Applets 2 2 2 mn 67 4 5 Undo Redo and Clear All 2 222 n nn 68 4 6 Custom GUI elements 2 2 2 o e e e 68 4 7 Board Resource Loading 2 2 2 nommen 69 df ll URL Loading 0 2 aus rd e 71 4 7 2 Requests to Computer Algebra Systems 73 41 332 Decoding ri ea men ae 75 die Ch lklets nummer a ka Te a A Sn Med ae weh 76 4 7 5 Resource Handling 77 4 8 Stroke Delivery 2 0 00 20 eee eee 77 4 8 1 Chalklet Strokes 2 222 2 nennen 77 4 8 2 Handwriting Recognized Strokes 2 2 2 2200 79 4 9 Mathematical Handwriting Recognition 79 4 10 Applet Control cod ma 7 a a ae oe 82 4 10 1 Applet Events
128. assumed that E Chalk is equally usable with any type of connection Asking students about the amount of note taking in E Chalk classes com pared to regular classes yielded about 60 of students taking at least as many notes in E Chalk classes as in conventional classes See Figure 8 11 for the dis tribution of answers Note that this tendency seems to be contrary to that of the summer term evaluation 10Note that these figures were collected before mid 2004 when media reported a notable loss in browser market share of the still dominant Internet Explorer See for example 33 11The same holds true for comparing Internet Explorer users with Mozilla Netscape users For other browsers the numbers of mentions were too low to get any statistically significant results As to the operating system the numbers for non Windows systems were also too low for comparison purposes 158 CHAPTER 8 EXPERIENCES AND EVALUATION 100 90 Dall courses 80 ETU courses 70 E FU courses 60 50 40 30 20 ge q mu E 0 more PDF both evenly more replay Figure 8 13 PDF was preferred over replay especially at TU where no audio was recorded 80 70 H Dall courses BFU courses FU seminars 60 H 50 40 30 20 10 0 clearly rather no change rather clearly ham pered hampered easened easened Figure 8
129. ated storage of lectures into an Oracle database was developed in addition to a middleware to provide access to the replay feature FKR02 The insertion tool was developed as a command line application but it was also integrated for automatic call in some early E Chalk versions The user interface was realized as a Web front end for a search engine allowing to search for lectures by different criteria such as lecturer topic dates keywords etc The front end supported direct replay of the search results in the browser as illustrated in Figure 6 10 The system also included management of the clients Jar files delivering the latest compatible client version instead of the client code used at the time of the recording Since Oracle database supports random access to stored BLOBs it is pos sible to use the fast forward rewind audio methods described in Section 7 3 1 While the audio format used at that time was WWR2 lacking a jump table for random access insertion in the database created a similar data structure to enable random access by time offsets using the middleware User administration for access restriction to the recordings are also featured Administration of the 6 11 HANDWRITING SYNTHESIS 119 Figure 6 11 Board output generated by handwriting synthesis for the input string handwriting synthesis x XX Figure 6 12 Tic Tac Toe test chalklet The computer places crosses the human player circles database conten
130. ates the signal processing chain The mixer settings saved in the profile are used to initialize the sound card mixer The mixer monitor will display a warning if it detects a change in the hardware configuration such as using a different input jack It supervises the input gain in combination with the mixer control The mixer control uses the values of the dynamic test to level out the input gain using the sound cards mixer This makes it possible to level out voice intensity variations Coughs and sneezes for example are leveled out see for example Figure 5 6 Note that the success of this method depends on the quality of the sound card s analog mixer channels Sound cards with high quality analog front panels however are becoming cheaper and more popular Mixer control reduces the risk of having feedback loops Whenever a feed back loop starts to grow the gain is lowered As in analog compressors used in recording studios the signal to noise ratio is lowered For this reason noise filters are required To reduce noise the DC offset of the signal is removed the sound card back ground noise level recorded in the profile is used as a threshold for a noise gate and the equipment noise is taken as a noise fingerprint The fingerprint phase is aligned with the recorded signal and subtracted in frequency space This High DC offset implies low quality of the card s analog to digital converter 8The analog pre amplifiers of the m
131. ation dialogs tends to condition the users so as to give a quick answer even before the request is consciously noticed Ras00 For example requiring a con firmation for each file deletion quickly trains to confirm any deletion without thinking Nor98 This does not only fail to protect against involuntary deletion anymore it also means continually having to do one click more than necessary 8 Typically those tasks already occupy the user s visual attention Visual feedback on the mode has to compete for the user s attention Using different sensory channels is thus more effective for example auditory feedback can also reduces mode errors Mon86 This observation caused the introduction of semi transparent dialogs in the Mac OS 32 CHAPTER 2 USER INTERFACE Accessories E Adobe lk 1 2pre Documentation ure 55H Client Audio Profile Wizard E Ghostscript gt Uninstall gt Board Macro Recorder Microsoft Office gt fl E Chalk Server B E Chalk Lecture Repair Tool a Mozilla fl E Chalk Server Console Exymen r IM NetBeans IDE m PrintMe Internet Printing Startup E UltraEdit E X Win32 5 4 TR Programs Internet Explorer 4 Documents Figure 2 2 The E Chalk package added to the Windows start menu Responsiveness Responsiveness of applications is essential to avoid user frustration Joh00 Giving no feedback for longer durations is very irritating to users They be come concerned that
132. avid Goldberg Frank Halasz William Janssen David Lee Kim McCall and Elin Pedersen Liveboard A large interac tive display supporting group meetings presentations and remote 174 Eri94 Esp04 Eul04 EW90 FGM 97 FGM 99 Fit54 FJHWOO FJK04a FJK04b FKRO2 BIBLIOGRAPHY collaboration In Proceedings of the conference on Human fac tors in computing systems CHI pages 599 607 Monterey CA USA May 1992 ACM press Hans Eriksson MBone The multicast backbone Communica tions of the ACM 37 8 54 60 August 1994 Margarita Esponda Argiiero A New Algorithmic Framework for the Classroom and for the Internet PhD thesis Freie Universitat Berlin Institut fiir Informatik August 2004 Stefanie Eule Interaktive Whiteboards in Berliner Schulen Chancen und Probleme eines neuen Mediums Magister s thesis Fachbereich Erziehungswissenschaft und Psychologie Freie Uni versitat Berlin June 2004 David B Elliott and David Whitaker Decline in retinal function with age Investigative Ophthalmology Visual Science 31 4 357 1990 Roy T Fielding Jim Gettys Jeffrey C Mogul Henrik Frystyk Nielsen and Tim Berners Lee RFC 2068 Hypertext Transfer Protocol HTTP 1 1 IETF IESG January 1997 Roy T Fielding Jim Gettys Jeffrey C Mogul Henrik Frystyk Nielsen Larry Masinter Paul J Leach and Tim Berners Lee RFC 2616 Hypertext Transfer Protocol HTTP 1 1 update IETF I
133. ay resolution The Auto button sets the size to full screen Initial values for the board drawing tools colors and sizes can be set with the logarithmic style size choosers shown identically in appearance in the board interface The boards mathematical handwriting recognition can be bound to a drawing color and a computing algebra server program can be connected for use on the board See Section 4 8 for a detailed description of the handwriting recognition For details on the setup of computer algebra systems see Section 3 3 The dialog allows to choose the board background color among 18 different colors In practice however black is almost always used with a few users preferring white for similarity with a paper background Black not only yields the best resemblance with the blackboard white on black writing is better readable than vice versa at least for vision impaired and older people Gat03 Byr00 The board supplies access to a number of bookmarks see Section 2 4 2 These include bookmarks for images and Applets to be pasted to the board for board macros to be played for CGIs to be queried and chalklets for interactive board animations Each of the associated buttons starts a bookmark editor An editors allow to add URLs and associate labels and icons with them see Figure 2 5 The editors support editing by drag and drop and allow to import the files of a directory as a list of bookmarks For macros replay speed can be set an
134. blet PC edition a Java interface to the recognizer engine has been developed which allows to be queried by RMI calls With this approach one can use the Python chalklet on any platform with using the handwriting recognizer by remote calls as long as the server program can be connected via a network connection When E Chalk actually runs on a Tablet PC Windows the server can be started locally and queries can be made without a network connection 6 13 Post production with Exymen Although E Chalk has been conceived as a tool for capturing live and sponta neous lectures instructors would like of course to edit the result of a lecture in order to correct errors or just to eliminate superfluous parts By editing recordings can be shortened parts of lectures can be reused and recombined and lectures can be dubbed For this an editor capable of handling the three multimedia streams used by E Chalk is needed audio and video streams as well as the event based board format must be supported Instead of writing a specialized editor for E Chalk a generic editor for streamed data formats called Exymen Fri02a Fri02b 25 has been developed It provides a single GUI for all kinds of multimedia editing and a framework to represent multimedia data A number of formats are handled by plug ins filling the abstract data containers of the Exymen API and providing editing operations on them To make for convenient extension of the editor a pow erful plu
135. board content 26 times A few students also noted that the lecture was easier to follow with the system 15 times The most common complaint was concerning the stability of the system 61 times This impression however is explained by a hardware problem in the PC running E Chalk in the main TU lecture hall The PC used exclusively for E Chalk lectures had a faulty memory chip frequently causing the OS or the E Chalk applications to crash Unfortunately the cause of this problem was not identified until late in the term However the several damaged E Chalk recordings led to the development of the lecture repair tool described in Section 6 6 Also common were complaints about the visual quality of the board image 58 times mainly remarks on resolution and the relative size of the board 51 times A likely cause for these shortcomings is the displayed resolution being too low forcing the instructor to write bigger letters for improved readability While the digitizer whiteboard hardware is theoretically able to recognize the pen location way beyond the accuracy of the human hand the resolution is limited by the screen resolution of the projector and the controlling computer s graphics card In fact it is not even desirable to use very high resolution here as this would make the replay on computers with lower resolutions very inconvenient unless extra mechanisms for small screen rendering are added to the client as discussed in the con
136. calculator Note that requests to computer algebra systems must be cancelable as it is possible to send an infinite recursion or computing requests that are beyond the power of the computer e g 9 A connector is implemented by inheriting from the abstract class de echalk util EvaluatorKit It provides the localized setup information for the E Chalk setup dialog described in Section 3 3 and a static factory method to build an object implementing the de echalk util Evaluator interface The EvaluatorKit also defines the parameter list for the factory method and how the parameters are set by user in the above mentioned setup dialog If an Eva luatorKit is activated a connection to the computer algebra system is made by building an Evaluator at startup 13To be more precise in Java 1 3 URLs for which the server s response code was over 400 and where the URL file path does do not end in htm html or txt trigger a java io FileNotFoundException whenever calling any of the methods getResponseCode get ResponseMessage getErrorStream getHeaderField String name long def or get InputStream See Java bug 4160499 and the related 4150792 4191207 4222009 4300174 4314717 4406592 4492994 4655826 43 74 CHAPTER 4 BOARD SERVER Figure 4 8 Maple plot without transparency left and modified for transparent background right The Evaluator is notified of the board s background and is registered as a listener
137. can redefine the property echalk conf dir to point to an alternative directory All secondary configuration files are referenced by using paths relative to this property To manage several users working with a single E Chalk installation but indi vidual configurations the echalk conf dir can be set to a user defined direc tory For example it can be changed to user home echalk using the Java system property user home pointing to the user s home directory This also avoids write permission problems when E Chalk configuration files are installed write protected against non owners on multi user platforms To avoid requiring first time users to manually copy these configuration files this is handled automatically by E Chalk When the echalk conf dir direc tory does not exist or does not contain the configuration files the files are copied from the original configuration directory and its subdirectories The original configuration directory in turn is defined by the property entry echalk conf src dir A property named echalk conf src filter defines a file name filter for the files to be copied to prevent the copying of system files like the error log file 3 2 Data Model of the Settings The class echalk main Settings serves as a data model for the collected input elements of the setup dialog which is stored in the lecture settings file with its file path defined in the configuration entry echalk lecture conf It is saved in the Java P
138. ch the microphone on The system warns the lecturer by displaying a warning dialog see Figure 5 8 Of course if the quality of the recording equipment microphone and sound card is too low even enhanced recording will not be enjoyable for the listener However first experiences FKST04 FJK04b showed that the system produced good quality when used with good amateur or semi professional grade equip ment which can be employed at significantly lower cost than professional audio equipment and audio technicians In addition the system s wizard already as sisted a number of users in analyzing their audio hardware for shortcomings 5 3 The WWV Video Server The video subsystem called World Wide Video WWV was designed as an Internet streaming system that runs on any hardware or platform just like WWR2 3 Explicitly included are small computers such as handhelds or mo bile phones Since video data processing is more expensive than audio data processing it was decided to create an asymmetric system It was assumed that the server side has more computational performance at hand than the replaying client The bandwidth requirements for high quality video are much higher than 9A typical situation that changes humming is when the light is turned on or ofl 5 3 THE WWV VIDEO SERVER 101 00 01 E Chalk 1 Figure 5 8 The microphone floor noise level has sunk batteries have to be changed for board or audio data while t
139. chulen 10 project twelve schools have been equipped with electronic boards since early 2003 One of these boards is shown in Figure 8 1 Feedback from personal contact indicated the highest levels of E Chalk use in elementary schools where writing and drawing on boards was used more frequently than in higher grades However the overall usage profile remained comparably low as many teachers were reluctant to familiarize themselves with the technology The evaluation report Eul04 recommends training the teachers with the whiteboards and providing libraries of digital material tailored for school teaching like the Lokando SCHOOL Themenbank 54 The largest German museum of science and technology the Deutsches Mu seum 18 in Munich uses E Chalk in a project where visitors are asked to record a description of their favorite experiment from the Chemistry exhibition see Figure 8 1 To promote the use of audio in the recording the visitor is engaged in a conversation about the experiment by a museum employee sitting vis a vis during the recording Some configuration settings were introduced to the E Chalk board for this experiment to further reduce the tool dialog op tions However the Deutsches Museum team uses the standard setup as it was thought from their initial experiments that everyone immediately understands 143 144 CHAPTER 8 EXPERIENCES AND EVALUATION Figure 8 1 Left English lesson with E Chalk at a German school the
140. comed the extra flexibility in learning both for increased independence in time and in location There is a small tendency below statistic significance that students reduce the amount of note taking compared to regular courses Lecturers skills regarding software handling improved noticeably during the term statistically highly significant i e an error probability of less than 1 According to the interviews time needed by lecturers to get fully accustomed 5The original German names of didactic categories in the questionnaire were An schaulichkeit Verst ndlichkeit Nachhaltigkeit Konzentration Wissenszuwachs Interaktion and generell 8 3 STUDIES DURING SUMMER TERM 2003 151 25 20 10 06 08 17 06 03 24 06 03 01 07 03 08 07 03 Figure 8 7 Number of E Chalk replay accesses in the evaluated FU Berlin course from June 10th until the day of the exam on July 14th ranged between one and four lectures Sch03 judges this as an indication for the easy handling of the software The questionnaires included requests for commentaries for advantages of E Chalk for disadvantages of the system and for suggested improvements The most frequently mentioned advantage was a clear readable board im age mentioned 189 times followed by comments on remote access 73 times revision material 62 times enhanced visualization facilities with Applets and images 36 times and the elimination of need for copying the
141. component and sets its ComponentUI to an echalk util LogarithmicSliderUI which provides the logarithmic style in painting and control The echalk board gui URLDialog allows the user to choose a bookmark To make the Java Swing list component an instance of the javax swing JList class display the thumbnail icons saved with the bookmarks an instance of a custom list cell renderer class is set to the list The dialog also shows a summary of the bookmark properties in the tooltips of a bookmark which can be especially helpful for bookmarks with parameters namely for CGIs chalklets and macros See Figure 4 5 for an example The bookmark lists for images and Applets are just named links to files with out any extra parameter data needed to load the resource For these bookmark lists the displaying URLDialog also features an input line for the user to type in a known URL address For convenient selection of local files a file chooser can also be launched Its file filters are preset to show only relevant files 4 7 Board Resource Loading The class echalk board rc RcLoader handles access to external resource data i e Applets images CGI calls requests to computer algebra systems as well as loading animations chalklets After loading it passes the data on to resource 5See Section 3 4 6The class echalk util CellRenderer implements the java swing ListCellRenderer in terface and is used here It also implements the java swing table
142. ct replay e Changes to the Applet s component hierarchy are not handled The event listeners are only registered to Applet components that exists after the Applets init method returned When the Applet adds new 29See Section 4 11 2 for the event format for logged Applet events 84 CHAPTER 4 BOARD SERVER components afterwards events delivered to them will be lost in replay This problem can be solved by adding a java event ContainerListener to the Applet and all its subcomponents that inherit from java awt Container and can thus contain other components The listener is then notified whenever an adding or removal of components happens and can add and remove the event listeners accordingly Extra windows are not handled Applets opening their own windows do not only break the board metaphor but the windows and their subcomponents go unnoticed by the described recursive event listener registration All events on these components will be lost On the server side it would be possible to prevent the Applet from ac cessing the frame display methods via a java lang SecurityManager throwing a java lang SecurityException on an access attempt The SecurityManager can also be used to prevent the Applets from increas ing the priority of their threads or accessing E Chalk s system threads Unfortunately this mechanism cannot be used on the board client to achieve identical results for the replay the board client is an unsign
143. ct their understanding of a subject In reality most Web based learning courses rely on delivering informa tion and rote learning Interaction is usually limited to online multiple choice tests and possibly a few interactive experiments such as Java Applets or flash animations Complex interaction and feedback are almost non existent MNO2 at the very best providing chat e mail discussions or automatically examined multiple choice tests Tsi99 Since even simple and linear material is labor intensive and expensive to produce more complex approaches are rarely realized and almost always stay in the realm of theoretical concepts On the other hand a huge amount of content is already produced on a regular basis in traditional teaching As Tsi99 puts it Universities generate content every day through their courses and seminars They then throw it away There is a certain charm with this approach but it is not cost effective Trying to avoid the expenses of standard e learning module authoring many universities resort to mere video capturing of their standard lectures see for example 106 This approach has the advantage of making use of existing teaching qualifi cations of the lecturer instead of requiring the lecturer to acquire new teaching skills If the recordings manage to transport the feeling of the lecture they can produce high quality teachings as a kind of by product of traditional teach ing The resulting e learning conte
144. cutive commands For entering text with Dasher WBM00 the user selects the rectangle for the next letter where size and position of the rectangles depend on the probability of the letter as the next input element This makes it easier and thus faster to select a probable letter Note that the size determining probabilities are language model dependent The drawback of the system is that it requires constant visual attention to operate and it is still slower than the traditional keyboard 1 5 Pen based Office and CSCW Tools Boards are often used in companies as a tool for presentation and brainstorm ing support In offices they are also used as memory extension tools as well as a semi public drawing area shared with collaborating visitors Myn99 When digitizing whiteboards entered the market the first applications were in com mercial settings Other pen input enabled electronic devices are also prevalent in commercial contexts like PDAs and Tablet PCs As a consequence pen based interactions have mostly been researched in the context of computer supported collaborative work CSCW and office tools Most CSCW tools provide shared workspaces according to the WYSIWIS prin ciple what you see is what I see and often allow one to capture the results of a session collaborative capture systems though in most cases they allow only a static snapshot of the result Many of the research projects are closely related to the idea of Ubiquit
145. d extra information on the macros is shown like minimum board width required for replay and background color The CGI bookmarks have a list of CGI parameters associated with them Each parameter has a number of entries 1l Many electronic magnification tools for vision impaired users include the option of reverse polarity display because of negative contrast white letters on black being often more readable than positive contrast Similarly the Windows magnifier tool optionally allows reverse polarity for accessibility A known cause for inverse polarity being superior is that physiological changes in older eyes can lead to an increased sensitivity to glare EW90 Also experiments showed that vision impaired readers with cloudy ocular media perform better with white letters on a dark background LRPS85 12Board macros are generated with the macro recorder described in Section 6 9 2 4 THE E CHALK SERVER APPLICATION 35 Echalk Chalklet Bookmarks Entry Edit Bll ale Jm allay J Echo Demo Chalklet horizontal E Echalk Image Bookmarks Entry Edit Balan e x a Name l URL fish file gb fish jpg fractal file ghdfractal gif FU Berlin computer sc file gbgfu inf jpg E gepard file gb gepard jpg Gerald htip Ikazan inf fu berlin deechalk gh4gerald jpg grouper file ghdgrouper ipa Lars http kazan inf fu berlin defechalldgtulars jpg latest weather from M http foiswww eumetsat org idds images outlate lightn
146. d text images are referenced indirectly in the page contents and the image data representation may be split into several PDF objects for example a separate object for a color table If the PDF contains text the font must also be included as a PDF object but in the converter s output a single font object is shared by all pages TTo be more exact PDF stream data of PDF objects may be compressed 8The compression factor achieved with flate is usually slightly superior to LZW and much better than RLE Also LZW encoding was still protected by patents when the converter application was developed The US patent Wel83 owned by Unisys expired on June 20 2003 and the counterpart patents in the United Kingdom France Germany and Italy expired on June 18 2004 The Japanese counterpart patents expired on June 20 2004 and the Canadian counterpart patent expired on July 7 2004 See 100 IBM also holds a US patent MW83 with claims to LZW that will expire on August 11 2006 108 CHAPTER 6 TOOLS CONVERTERS ADD ONS Figure 6 2 Full GIF image top left truncated non interlaced image top right truncated interlaced image bottom left and reconstruction of this in terlaced image bottom right Original image from the libungif 53 package version 4 1 0 cation overhead of about 20 bytes is bigger than the gain from the compression Note that compression can be more effective having all the data of a page in a single content object
147. d to a fixed number of actions A rarely used option of the tool dialog is a button to clear the whole board 19The maximum size of mouse pointer images depends on the platform s window system On Windows the maximum image size is 32x32 pixel on X windows systems up to 64x64 pixel are allowed A possible improvement would be to show the drawing tool pointer in the current drawing color 2 4 THE E CHALK SERVER APPLICATION 39 Echalk Tools El Echalk Load Image Bookmarks FU Berlin computer science buile math lecture at TU Berlin El sketch of echalk system Latest weather from METEOSAT arabic coin Ernesto R fa Christian lhttpkazan inf fu berlin defechalkigi ernesto j URL outlatestiR 108 2_08_0_latest jpg Figure 2 10 Left E Chalk tool dialog Below the two action button rows are the radio buttons for selecting a chalk color or the eraser tool The three sliders at the bottom control the size of the chalk tool the eraser tool and typed text respectively Right Dialog for selecting an image to add to the board content Drag Handles The virtual length of the board is not limited In the setup the board can be configured to feature a vertical scrollbar However the board interface provides another possibility for scrolling which resembles the interaction style of a tradi tional blackboard more closely At the top and the bottom of the screen two
148. deactivated as some users have trouble when hitting the extra button by accident especially for the smaller pens that come with digitizer tablets and Tablet PCs 8For image file chooser dialogs a preview function still has to be added 8 3 STUDIES DURING SUMMER TERM 2003 153 better 5 40 rather better 4 ERA 36 35 36 u u 5 same 3 rather worse 2 worse 1 T T y T T r cleamess perceivability sustainability concentration cogrition interaction gereral increase Figure 8 9 Average scores on aspects of didactic qualities of E Chalk courses have personalized settings which have now been implemented see Section 3 1 2 A Mathematics lecturer requested integration with Maple as his department worked with Maple instead of Mathematica Again this request has been im plemented see Section 4 6 2 When questioned about advantages and disadvantages of the system most of the instructors answers were similar to the most frequent students comments In addition they judged as being positive that the teaching content of traditional classes needs no restructuring when presented with the system enabling them to reuse their old materials Some lecturers missed the small pauses introduced in traditional chalk lectures by the action of wiping the board Additional disadvantages were observed in the hardware setup At TU Berlin both mobile and fixed digital whit
149. dec together with gzip compresses down to 20 kbps To achieve a good trade off between sound quality compression and execution speed the ITU ADPCM Int90 was modified The result were 4 bit 3 bit and 2 bit modified ADPCM codecs that combined with gzip give an effective average compression of 30 kbps 22 kbps and 15 kbps WWR3 Codecs In order to improve the sound experience for remote users with Java plug ins installed in browsers supporting 16kHz Java 1 3 or later the WWR3 audio format uses 16 bit 16kHz linear mono audio stream This can also be played directly if the browser uses Java 1 3 or later In Java environments that only support 1 2 or earlier the audio client converts the data to 8 bit 8kHz u law to replay them By this means all Java enabled browsers can play back the stream while users with a more recent Java version can enjoy the audio at a higher quality The higher sampling rate increases the amount of data WWR3 codecs have been implemented for 32kbps 48kbps 64kbps and 128kbps with the numbers designating the maximum bandwidths needed However the format change was accompanied with the introduction into the recording system of filtering techniques that drastically reduced the amount of recorded noise In 2See Section 5 2 for a description 5 2 SMART AUDIO RECORDING 95 3 Input Line Sound Card Equipment Dynamic Introduction Detection Noise Noise Test Esas Simulation Report pame Test Storage Fig
150. ding with off the shelf Internet video tools is inadequate for lecturing content Writing and drawings from slides or from a blackboard are not encoded appropriately Compression of a single video frame with state of the art video encoding technology relies on dropping the higher frequency parts from images resulting in the loss of sharp edges Either the content becomes unreadably blurred or using only weak compression the video stream takes up lots of bandwidth JPEG image compression is based on the same approach see Figure 1 1 for an illustration of the effects Thus these systems require the instructors to modify their teaching style for the sake of tele presence quality Tsi99 any teaching materials must be prepared with consideration of legibility to tele viewers The writing on blackboards or the trans parencies shown on overhead projectors may be clearly visible to classroom participants but extremely hard to read for remote par ticipants Even then considering the bandwidth restrictions the typical remote user faces at home low resolution and lossy encoding often result in unacceptable quality One approach to avoid badly encoded writing is to send lossless encoded presentation slides of the talk separately instead of encoding them as video 3The Just In Time Lectures concept is described in Section 1 8 2 4 CHAPTER 1 INTRODUCTION AND RELATED WORK image They are either sent as a collection of all slides requiring
151. ds from Handwriting Recognition To automatically generate keywords for indexing purposes both speech recog nition on the recorded audio data HK W02 Hiir03 and handwriting recognition on the board data may be used For the given purpose even a relatively low recognition rate is sufficient The performance of the handwriting recognition that comes with the Tablet PC Edition of Microsoft Windows XP has recently been tested with recordings from the Classroom Presenter described in Section 1 7 2 The recognition engine was tested on slide annotations from five lecture recordings with segmentation done by manual preprocessing Recognition was reported as good 68 even though the lectures are considered to be a difficult recognition task by the authors AHP 04a An application has been developed for E Chalk to extract text from board writing using a handwriting recognition The04a Like in the Classroom Pre senter project it uses the handwriting recognition that is part of the Microsoft 19For a description of AOF and its tools see Section 1 8 6 116 CHAPTER 6 TOOLS CONVERTERS ADD ONS t Chalk Recognition Test Application a Recognizer Input gt seinen rattle le SABIDO cp converted 314 2216 GHT el m 1184F oen Lirw 122636122564 0100 PSF omnes 11 a cs43g1 0010053 HOENDCRCOSA 268451 008 ZAS 7RCOTDOS a 1303 osuen 2547513052354 001005 0 i NdtFomtLins 1305498131 445004005 gt ls o Diese
152. dth produced by chalklets low enough is to change the event format to a more compact representation The format should be changed to a binary one with a differential encoding being applied The event data will compress very well using a differential encoding because it consists largely of long sequences of line segments with its data entries only slightly changed position on board or even identical color and stroke width An additional entropy encoding like gzip can be applied afterwards except for live transmission where the events cannot be gathered in packets as they have to be transmitted without delay While compression will still not allow for an unlimited rate of chalklet events it permits the limit to be relaxed As a drawback of using compressed event encoding the task of providing a repair tool for damaged event files will become much more difficult see Section 6 6 For the text encoded event file one may consider to use XML encoding The main advantage of using XML is the availability of generic parsers for the overall structure Also one gains a self documentation of the format with the DTD for the XML data While Java includes XML parsing support since version 1 3 there is no XML parser in 1 1 Because the events need to be parsed on both the client and server sides E Chalk needs to implement its own event parsing anyway Therefore 32Serial mice report at a rate of 33Hz PS 2 mice default to 40Hz on Win98 ME and to 60 H
153. ducational Technology amp Society 4 3 2001 Chris R Jesshope Towards the dynamic publication of multime dia presentations a strategy for development In Proceedings of ALT C 2003 Sheffield UK September 2003 Kristian Jantz Gerald Friedland and Lars Knipping Conserving an ancient art of music Making SID tunes editable In Com puter Music Modeling and Retrieval 2003 pages 76 84 Montpel lier France May 2008 Kristian Jantz Gerald Friedland and Ra l Rojas Trennung von Dozenten und Tafel in einem E Kreide Video Technical Report B 04 07 Fachbereich Mathematik und Informatik Freie Universitat Berlin June 2004 Jeff Johnson GUI Bloopers Don ts and Do s for Software Devel opers and Web Designers Morgan Kaufmann San Diego CA USA April 2000 Jeff Johnson Teresa L Roberts William Verplank David C Smith Charles H Irby Marian Beard and Kevin Mackey The Xerox Star A retrospective IEEE Computer 22 9 11 26 28 29 September 1989 Chris R Jesshope Alex Shafarenko and Horia Slusanschi Low bandwidth multimedia tools for web based lecture publishing IEE Engineering Science and Educational Journal 7 4 148 154 1998 Bob Katz Mastering Audio The Art and the Science Focal Press Elsevier Oxford UK 2002 Gordon Kurtenbach and George W Fitzmaurice United States Patent No 6 414 700 System for accessing a large number of menu items using a zoned menu bar 1998 Silicon Graphics Inc fi
154. e C Wed 0830 Persuasion F ogg C Wed 0830 Persuasion F ogg C Wed 0830 P ersuasion F ogg Note Note Tanday Tanday hearst 1998 04 22 09 29 26 1998 04 22 09 31 05 1998 04 22 09 31 17 pen ak Ci me errr bray Figure 1 9 The Web based NotePals Note Browser showing thumbnails of the notes matching the query Picture from DLCT99 The Room allows visitors to interact with the room components via PDAs con nected with PPP over serial cable or with WLAN FJHW00 They can control the room light the projectors PowerPoint presentations shown on the Mural annotate them called Smart PowerPoint by the developers and share data objects and applications In contrast to the 1 Land project the Room strategy is to support standard Unix or Windows applications as regular components of the environment For managing the communication between different components the Java based room display manager uses a special event heap transmitting the events to all receiving clients The transmission strategy is specially designed for ro bustness Win01a The Room applications and interaction schemes researches focus on CSCW tools brainstorming and direct interaction with board elements mainly modi fication of size and position Their preferred user interface metaphor are a pen and virtual sheets of paper Win01b To achieve what they call a fluid interac tion using pen input the command mechanis
155. e 6 9 It allows the user to define the storage path and macro name as well as optionally appending the macro to the macro bookmark list The entries for macro name and path are preset to generic names enabling the user to start recording immediately If a previous recording made is encountered the name is generated from the previous recording s name plus a trailing number or by increasing an already existing trailing number Path name generation is done the same way only adding capabilities to handle name clashes with existing files Path information is saved from the last macro recording and used to determine the preset to be displayed at the next macro recorder start When the user hits OK the application starts recording after checking for any write conflicts like possible overwrites to be confirmed by the user or any storage permission problems The code that prepares a directory for recording and starting the recording components is part of the main application described in Chapter 3 With the main E Chalk application being a Launchable the macro creator just uses it as a subcomponent to be started Normally this would show the main setup dialog To prevent that from appearing certain configuration properties are redefined Others properties are used to suppress dialogs like the Append Overwrite Cancel dialog as the macro recorder al ready handles such conflicts itself The redefinition of the properties is realized by calling the Launc
156. e RealPlayer or a combination of these techniques See Sections 1 5 to 1 8 for details 12See Section 1 8 1 for a description 13While there are some browsers that are not able to run Java Applets this is a usage requirement that is much lower than all available alternatives that allow for dynamic playback It was also decided to stick with Java version 1 1 for the replay as most pre installed Java browser plug ins are still of this rather early Java version 1 3 BOARD HARDWARE 7 Figure 1 3 The ChalkBoard PowerPad by Chalkboard Inc was an early exam ple of a digitizer tablet It was available for the C64 and the Atari 800 XL XE and came with educational software Additional edutainment programs were sold for the PowerPad Each came with a plastic clamshell box to serve as a cus tomized template that was laid over the PowerPad s surface Image from 51 approach merges classroom teaching distance teaching and the production of courseware into a single task Not only does the replay allow for pure distance teaching scenarios it also relieves the classroom students of the burden of writing down everything and gives them more time to participate in the lecture as the recording is a dynamic script of the class where the teacher s side notes are not lost Experiences showed that automatically generated script does not eliminate note taking by students Instead their notes become less literal copies of the board content and more sum
157. e Set Icon gt Choose menu Raw images as produced from the Thumbnail and Import sub menus of Set Icon are stored as hexadecimal zipped RGB data For the icon size of 16 16 used in the bookmarks even uncompressed raw RGB pixel data is often smaller than standard image formats like GIF or PNG due to the size overhead from format headers For image and Applet bookmarks these are the only informations that are stored CGI bookmarks additionally provide a list of CGI parameters A pa rameter is denoted by the key arg and has entries for the parameter s name the HTTP method to send it for the CGI request GET or POST and a string to prompt the user for input See Listing 3 3 for an example entry Macro bookmarks use the key value pair entries to store the board width and board background color used in the macro to enable the board to decide 13The document type definition or DTD provides the grammar for a class of XML docu ments BPSMt 04 14The bookmark dialogs of the board show a default icon for bookmark entries that do not define their own icons 15The supplied images are installed as Jar bundles so the URL uses the Java specific jar protocol with the syntax jar lt URL of jar file gt lt entry in Jar archive gt 3 5 AUDIO PROFILES 51 lt entry gt lt name gt Calendar lt name gt lt url gt http www online lectures org cgi bin cal cgi lt url gt lt thumbnail gt lt href width 16 height 16 gt jar file l
158. e and MacroMedia Dream Weaver the second type includes ToolBook 89 SWISHmax from SWISHzone 90 MacroMedia Director 59 and AuthorWare 58 Most multimedia authoring tools require specific runtime environments or browser plug ins for replay for example Authorware Player Flash Player ShockWave Player others can create native applications e g Multimedia Fusion 15 can compile its animation to Windows applications In addition to these general multimedia authoring systems there is a range of systems that focus on generating interactive educational material on spe cialized subjects for example Cinderella RGK99 11 for Interactive Geome try and Java View PKPRO2 45 for 3D geometry viewing and mathematical visualization both producing using Java Applets Another example is Flash dance Esp04 creating Flash animations for algorithm visualization The following sections describe a number of authoring systems focusing on the production of courseware for university teaching 1 6 1 MANIC The MANIC SSL 97 PK99 BKT02 60 multimedia asynchronous networked individualized courseware system delivers slides as HTML documents and GIF images optionally with timed highlighting effects This is synchronized with an 21MacroMedia AuthorWare is even specifically targeted at authoring e learning content 1 6 COURSE AUTHORING SYSTEMS 17 Packet Switching roth did ao ch
159. e annoying when one wants to quickly test modified versions 15The audio profile wizard is described in Section 5 2 3 36 CHAPTER 2 USER INTERFACE Echalk Audio Profile Properties General Equalizer Report 3 Gerald R006 Aerobic Mic fland Monday June 7 2004 3 02 28 PM System DATAWALL2 Windows XP 5 1 x86 Sound card dic Audio DESO Bl Echalk 2 General A Board Y Audio PP viieo ive Server amp PDF Codec 64kbps v Audio Configuration Profile Echalk Audio Profile Properties General Equalizer Report lt Undefined gt Christian R006 Aerobic Mic Gerald R006 Aerobic Mic Lars R006 Aerobic Mic Raul R006 Aerobic Mic Yvonne R006 Aerobic Mic Echalk Audio Profile Properties Delet pea General Equalizer Report Properties fool eS Sound card 91 0dB Theoretical Sound equipment 75 0dB Average DC offset Codec 50 0dB Signal to noise ratio 56 0dB Activate lt Monitor Display Warning on Lost or Weak Microphone Signal arm Rating Sound card quality good Equipment quality good Signal level sufficient Estimated rate of unintelligible words 1 10 330 Automatic Gain Control true CPU speed sufficient yes Figure 2 6 Left The audio settings page Right The tabbed pages on the audio profile properties a new profile With a selected profile the audio settings allow to
160. e archivemode This parameter gives the location of the recorded audio data as a relative URL If the value ends with a slash it is assumed to be a directory that contains the encoded WWR3 audio file content wwr and the packet index 13The delay compares well to other streaming systems For example streaming with the Real Presenter has a one way delay of 30s Even satellite phones have a delay of about one to two seconds ZS02 14Parameters that are supported only for backwards compatibility are omitted 7 3 AUDIO CLIENT 139 file index wwr see Section 7 3 1 Otherwise the parameter is assumed to be a WWR2 audio file or a WWR3 audio file if wwr3mode is set to on see below When this parameter is undefined the client assumes a live stream connection For historical reasons the parameter ondemandmode can be used instead of archivemode The default setup of the E Chalk system sets the archivemode parameter to audio for archived lectures When the WWR2 format was still in use the parameter was set to lecture wwr e port The parameter is the decimal port number to connect to on the live server When not given it defaults to port 9998 The parameter is ignored when replaying from archive e loopmode With the audio system originating from an Internet radio streaming sys tem the audio Applet terminates by default when reaching the end of the audio stream releasing all system resources The audio client terminates at the
161. e can track the instructor s developing the subject on the board The technical implementation of the teaching device is formed by the pedagogical needs instead of letting the device be purely driven by the technical development The E Chalk system has been widely used and it has been tested in a broad range of real life teaching Both the anecdotic evidence and the systematic eval uation proves the system to be an added value in classroom teaching as well as for a number of distance teaching scenarios The evaluation studies show it to be easy to use and that skills in traditional chalk lecturing transfer well into teaching with E Chalk The studies give a solid base to the assumptions on the advantage of the approach A number of possible improvements has been 167 168 CHAPTER 10 CONCLUSION identified many of them have already been implemented in the system some of them are still under development The most important need for enhance ment was identified in the audio playback quality which has been considerably improved by a number of different techniques The distance lectures are not substituting classroom teaching but supporting it Students are helped to revise the materials with a living and active script The remote viewer does not have to be familiar with any technical details to receive the lecture Only a browser is needed and no special software has to be installed All substantial information in the form of audio and dynamic b
162. e computing Terry Winograd Interaction spaces for 21st century computing In John M Carroll editor Human Computer Interaction in the New Millenium ACM press chapter 12 pages 259 275 Addison Wesley August 2001 Terry Winograd Brad Johanson and Armando Fox The interac tive workspaces project Experiences with ubiquitous computing rooms IEEE Pervasive Computing 1 2 67 75 April June 2002 Stephen Wolfram The Mathematica Book Wolfram Media Inc fifth edition August 2003 David R Woolley PLATO The emergence of on line community Computer Mediated Communication Magazine 1 3 5 July 1994 Karon Weher and Alex Poon Marquee a tool for real time video logging In Beth Adelson Susan Dumais and Judith S Olson ed itors Proceedings of the Conference on Human Factors in Com puting Systems CHI pages 58 64 Boston MA USA April 1994 Catherine G Wolf James R Rhyne and Laura K Briggs Com munication and information retrieval with a pen based meeting support tool In Proceedings of the ACM conference on Computer supported cooperative work CSCW pages 322 329 Toronto Canada November 1992 ACM press Catherine G Wolf James R Rhyne Lorna A Zorman and Harold L Ossher We met window environment meeting en hancement tools In Proceedings of the conference on Human factors in computing systems CHI pages 441 442 New Orleans LA USA April May 1991 ACM press Lynn D Wilcox Bill N Schilit
163. e remote user Parameters recognized by the video client Applet are e archivemode or ondemandmode Similarly to the audio client parameter of the same name this gives the URL relative to the code base of the directory containing the encoded video content wwv If the parameter is not set the client works in live streaming mode e delayoffset and masiclient These parameters are identical to the board client parameters of the same name used for synchronization with the audio client see Section 7 2 5 e server loopmode and port These parameters are identical in function to the parameters of the same name for the audio client see Section 7 3 2 The only difference is that the default value for the live port is 9997 7 5 Slide Show The slideshower Applet allows timed display of Web pages and to combine it with the other client Applets shown before The slide show in Figure 7 8 combines a sequence of pages with the replay of a talk The implementation of the slide show Applet does not support streaming of slide display command The slide events are loaded on startup before the replay starts and thus live transmission is not supported While the other client Applets can be run with the Java appletviewer the slide show Applet needs a browser environment as the appletviewer cannot display Web pages With no live server currently available for the slide show Applet this client currently supports only archived replay It cause
164. e transmission and replay from recording is realized as a Java application providing platform independent access The client application requires JMF to be installed 1 8 2 Just In Time Lectures With Carnegie Mellon s Just In Time Lectures 47 JITL the instructor s teaching is recorded on analog video Later this is digitized and encoded as a QuickTime movie Slides are stored as high resolution images and synchro nized with the video stream by the Just In Time Lecture Player An additional textual sections overview is added to provide contextual navigation The sys tem uses e mail for questions to the teachers and access to the online library a FAQ as interactive features Disk space requirements for the streams are quite high DC97 1 8 3 NoteLook NoteLook CKRW99 is a Dynomite successor but with the focus on note taking in a shared lecture instead of on office work It allows synchronous remote access to the lecture and uses the student s control for capturing individual recordings The students are equipped with wireless connected pen notebooks and can switch between different video channels usually takes on the room or on the presentation material The selected video stream is stored for replay and single video frames can be grabbed and annotated It also features a mode for automatic grabbing when the video image changes which can be used for detecting slide transitions See Figure 1 14 The system creates sta
165. ead Any user action on the board stops the macro The board behaves like a client while in macro play mode as pre recorded events are delivered to the board 4 8 Stroke Delivery 4 8 1 Chalklet Strokes The board sends all its users line drawing events as well as its undo and redos of line strokes to the associated echalk board rc StrokeSender instance Whenever a full stroke has arrived e g when the a drawing is terminated by a mouse up event or a stroke is undone the StrokeSender sends this to its echalk board rc StrokeReceiver Each registered StrokeListener like a Chalklet is encapsuled StrokeReceiver which checks the stroke events for their relevance to the listener In the case of a Chalklet a stroke is considered relevant if it occurred in the chalklet s observed area and if the stroke was not created before the chalklet became active The latter restriction is important for consistency when undos and redos occur Any relevant stroke event is passed on to the listener That stroke is handled in a separate thread for each of the listeners to avoid having a StrokeListener instance blocking the board See Figure 4 11 for an illustration of the stroke flow When a Chalklet wants to draw into its board area it sends Strokes to its ChalkletContext The strokes are put into the board s echalk board 19The implementation of the TextHandler also allows to handle text resources without a specified request position In that case t
166. eboard installations were tested These tests showed mobility not to be desirable Even slight movements possibly un intentional required the whiteboard to be recalibrated Even with fixed white boards the lecturers faced the problem that they needed some time before each lecture for calibration because the whiteboard projector was not fixed An other problem with front projection at TU was that instructors were sometimes looking into the projector light when turning to the audience While these prob lems could for example have been eliminated by a ceiling mounted projector the layout of the TU lecture halls did not allow for this solution Some lecturers reported trouble with their own shadow hiding the projection while they were working on the board The problem was increased by the low distance of the projector to the board resulting in a big shadow As a consequence of these problems most TU courses switched to the setup with an LCD tablet as pen input see Section 8 4 Summary The initial evaluation confirmed E Chalk to be a beneficial and usable system for teaching A number of minor improvements have been added in response to the evaluation feedback Fundamental assumptions on the system s conception were confirmed by the main conclusions Sch03 FKST04 of the study e Overhead work to use the software for lecturing is limited to the start of the term for a setup e The lecturer can easily integrate material from previous ter
167. ed Applet and is therefore not allowed to change the system s SecurityMa nager Applets may modify their listener registration The Applet logic may remove E Chalk s event listeners for example by removing all event listeners to replace them Also the logic of the Ap plet may rely on the registered event listeners an Applet state which we changed on the server side Platform or time dependent Applet behavior If the behavior of the Applet is dependent on random numbers given by the Java system or on execution time or information about the platform like OS name or Java version the Applet s behavior on the server side may differ from that on the client side In addition the different thread scheduling mechanisms of the underlying operating system may introduce race conditions and result in platform dependent replay behavior Finally the Applets themselves may rely on special versions of the un derlying Java system for example by using library classes not available in older versions by relying on running as a signed Applet or even by depending on the occurrence of bugs fixed in later Java version Different execution speed on server and client The execution speed of the Applet on the client side and on the server side can be expected to differ as they usually run on different hardware and share resources with different processes For example when the lecturer 30While this security mechanism does not really help for
168. en like input device A tool box type dialog allows to change drawing colors and widths It also provides access to a number of multimedia elements like adding images from a local hard drive or the Internet to the board or integrating interactive animations The board can be scrolled up and down vertically providing the lecturer with a virtually unlimited surface to write on Instead of using a desktop style scrollbar two drag handles are provided at the top and at the bottom of the screen The user grabs the board at a drag handle with the pen and drags the board up or down All actions on the board are tracked and recorded The development of the board content can be viewed by a remote learner both as a live transmission and as an asynchronous replay The voice of the lecturer is recorded along with the board stream These data streams already capture most of the teaching substance Optionally a video stream of the instructor can be added to give the remote lesson a more personal touch The system does not require the user to explicitly trigger a save Everything is automatically stored for viewing with a Web browser Remote Access When remote students open E Chalk s generated Web page of a given course with a browser replay starts in the form of self synchronizing Java Applets One 1Different hardware solutions for pen like input devices and big displays are described in Section 8 1 27 28 CHAPTER 2 USER INTERFACE A Rech
169. end of replay and cannot be played back To avoid this the param eter loopmode has to be set to on being basically inverse in effect to the board s autoclose parameter e syncalpha A problem when recording audio is that sound cards do not return the audio samples at a precise enough rate for our synchronizing purposes Even for high quality sound cards the actual duration of the audio sample usually differs from the requested duration by a few seconds per hour of recording The audio client determines its time offset by counting the audio samples while the other streams use the system clock With an average sound card used for recording the differences may add up to about 30 seconds for a lecture of 90 minutes and the offset may become quite irritating at the end of a longer recording To get decent synchronization between the board and audio streams the offset time computed by the audio stream is multiplied by a correction factor a This value is determined by the E Chalk application at the end of the recording as Tpoard Taudio Where Thoard and Taudio are the total times of the board and audio recordings This is done similarly for recording audio and video without the board stream The syncalpha parameter is set accordingly in the default templates stored as a string representation of a positive double value e wwr3mode When set to on the audio client assumes the input to be in WWR3 format even if the archivemode parameter i
170. ents The original brute force approach ran sequentially through all Form elements roughly about 2 000 objects per hour of recording On the server side board the resulting redrawing behavior was still perceived as fast enough in real lectures However rewinding and fast forwarding the client 1 This was even true for extensive tests running on a 500 MHz 256 MB Pentium III Windows laptop when the original data representation resulted in roughly 25 000 50 000 Form objects per hour of lecture The original data representation created a Form for each line segment drawn Now the board merges all line segments belonging to the same user stroke into a single Form which creates less than a tenth of the original number of Forms speeding up 65 66 CHAPTER 4 BOARD SERVER E 00 06 E Chalk 1 Figure 4 1 Typed text with the first line break created automatically and the second defined explicitly by the user with Shift Enter board felt too slow For fast redrawing a data structure that allows fast access to all visible Form objects in the order they are to be drawn is now used The virtual board space is separated into pages of the visible board area size For each page there is a dynamically growing array of references to all Form elements that intersect the given page stored in their order of creation For each given scroll offset the visible board area is then contained in up to two pages and only the Forms referenced in the pages
171. er 1998 ACM press Jitendra Padhye and James F Kurose An empirical study of client interactions with a continuous media courseware server IEEE Internet Computing 3 2 65 73 March 1999 Konrad Polthier Samy Khadem Eike Preu and Ulrich Rei tebuch Publication of interactive visualizations with javaview In Jonathan Borwein Maria H Morales Konrad Polthier and Jos F Rodrigues editors Multimedia Tools for Communicating Mathematics chapter 15 pages 241 264 Springer Verlag Heidel berg Germany 2002 John C Platt Fast training of support vectore machines using sequential minimal optimization In Bernhard Scholkopf Christo pher J C Burges and Alexander J Smola editors Advances in Kernel Methods Support Vector Learning pages 185 208 MIT Press Cambridge MA USA 1999 Elin Ronby Pedersen Kim McCall Thomas P Moran and Frank G Halasz Tivoli an electronic whiteboard for informal workgroup meetings In Proceedings of the conference on Human factors in computing systems INTERCHI pages 391 398 Ams terdam The Netherlands April 1993 ACM press Wolf Ulrich Raffel E Kreide Eine Java Multimedia Tafel f r die multimediale Lehre Master s thesis Fachbereich Mathematik und Informatik Freie Universit t Berlin October 2000 184 Ras00 RB93 Reb04 Rek98 RGK99 RKFFO1 RKRFOO RKRFO1a RKRFO1b RLJ98 RSFWH98 RSTGO3 BIBLIOGRAPHY Jef Raskin The H
172. er 2000 Shi Kuo Chang A method for the structural analysis of two dimensional mathematical expressions Information Sciences 2 3 253 272 1970 Patrick Chiu Ashutosh Kapuskar Sarah Reitmeier and Lynn Wilcox NoteLook taking notes in meetings with digital video and ink In Proceedings of the seventh ACM international confer ence on Multimedia Part 1 pages 149 158 ACM Press Octo ber November 1999 Louise Clark Introduction to Multimedia Conferencing and the SHRIMP Tools October 1998 Richard E Clark The cognitive sciences and human performance technology In Harold D Stolovitch and Erica J Keeps edi tors Handbook of Human Performance Technology Improving Individual and Organizational Performance Worldwide chapter 5 ISPI Jossey Bass Pfeiffer San Francisco CA USA second edi tion March 1999 Tongbo Chen Mingchao Ma Christoph Meinel and Volker Schillings A novel approach to e learning content creation In Proceedings of the Second International Conference on Multime dia and Information amp Communication Technologies in Education m ICTE pages 410 414 Badajoz Spain December 2003 Commodore Business Machines Commodore 64 User Manual 1982 CompuServe Inc Graphics Interchange Format tm A standard defining a mechanism for the storage and transmission of raster based graphics information June 1987 CompuServe Inc Graphics Interchange Format sm Version 89a Programming Reference July 19
173. erfaces 8These examples are not as uncommon as they might appear at first glance Both have been witnessed more than once by the author in sales presentations of whiteboard software for teaching 1 2 E CHALK THE IDEA 5 1 2 E Chalk The Idea The main fault in the approaches described lies in being technology driven focusing on what can be done with computer today instead of being led by the demands of teaching Looking instead for established teaching techniques one finds that the chalkboard has been an unmatched teaching tool for ages in many disciplines In 1855 the abolitionist Samuel Joseph May wrote about the introduction of the blackboard to classrooms being at his time the most modern instruction technology in the winter of 1813 ES 14 during my first College vacations I attended a mathematical school kept in Boston by the Rev Francis Xavier Brosius On entering his room we were struck at the appearance of an ample Black Board suspended on the wall with lumps of chalk on a ledge below and cloths hanging at either side I had never heard of such a thing before There it was forty two years ago that I first saw what now I trust is considered indispensable in every school the Black Board and there that I first witnessed the process of analytical and inductive teaching The chalkboard is an adequate interface metaphor for a common display used in teaching an audience It provides a shared view for instructor a
174. es recording of audio 4 times adding a scrollbar to the board 3 times download possibilities of the recording requested 2 times was avail able in all TU lectures and in some of the FU courses a bigger drag point 2 times already adjustable in the setup and recording of video 1 time 13See Chapter 9 14 Handwriting recognition is only integrated in the system so far for calculations see Section 4 8 and in experimental usage for indexing purposes see Section 6 8 162 CHAPTER 8 EXPERIENCES AND EVALUATION Chapter 9 Outlook Much good work is lost for the lack of a little more Edward H Harriman The system has already been extensively evaluated in university settings and to a lesser extent in K 12 schools For other application scenarios however an evaluation study has not been conducted yet Also the impact of the new audio system on the perceived quality still has to be systematically validated As mentioned before a number of possible future improvements have al ready been identified like a more intelligent page breaking algorithm in PDF production and many other useful improvements for example providing board backgrounds with lines grids and logarithmic chart paper style patterns Be yond minor features to be added research is desirable on the following points Methods for Keyboard Input on the Board The need for using keyboard in the board environment should be completely eliminated An obvious sol
175. et showing the lecture s position in time When the autoclose parameter is set to true for a live transmission the board frame closes when the lecture ends For the default setting this is not very useful as keeping the board open allows the student to browse through the board drawing In fact this parameter was introduced for a special setup where the board client is opened from the server side see partt on setup of FU data wall in Section 8 1 1 yoffset This integer parameter causes the client to shift the vertical scroll offset by the yoffset value The default value is zero The parameter is only used in a special setup where the board content is displayed with multiple board Applets See part on setup of FU data wall in Section 8 1 1 for the usage example server In practice this parameter is only used for debugging purposes It gives an IP address or host name to connect to in live mode Note that an 7 2 BOARD CLIENT 137 v Thread Stack ausgeben x ClassLoader Cache l schen 0 5 Trace Stufe auf lt n gt setzen entri MASI Console Copyright c 2002 by 6 Friedland L Knipping R Roja video E Chalk Video WWY client 0 62 Copyright C 2000 2002 by the E Cha audio World Wide Radio2 v2 60 Copyright c 1997 2001 by World Wide Ra board E Chalk Board Copyright c 2000 2002 by G Friedland L Knipping video Video is 192x1 44x5 entri Searching for MASI instances board Hito audio WWR2I video Frame dims
176. ethean co uk Python Programming Language http www python org RealNetworks Inc http www realnetworks com Thomas Richter Lineare Algebra fiir Ingenieure Eigenwerte und Eigenvektoren E Chalk recording winter term 2003 04 http www moses tu berlin de Mathematik LineareAlgebra WS_2003_2004 L4 Echalk linalg_richter_2004 01 27 196 WEB REFERENCES 81 Ra l Rojas Algorithmen und Programmierung I Bubblesort E Chalk 82 83 84 85 86 87 88 89 90 91 92 93 94 95 recording winter term 2001 02 http kazan inf fu berlin de lectures ALP1_WS01 bubblesort Ra l Rojas Algorithmen und Programmierung I Quicksort E Chalk recording winter term 2001 02 http kazan inf fu berlin de lectures ALP1_WS01 quicksort Ra l Rojas Bildverarbeitung Einf hrung zu Wavelets E Chalk recording summer term 2002 http kazan inf fu berlin de echalklectures SS02 BV wavelets Ra l Rojas Bildverarbeitung Farbdarstellung und Transformationen E Chalk recording summer term 2002 http kazan inf fu berlin de echalklectures SS02 BV farbe Ra l Rojas Rechnerstrukturen Zweierkomplement E Chalk recording winter term 2000 01 http kazan inf fu berlin de echalklectures misc rs_d Schule des Sehens http www schule des sehens de Ruedi Seiler Lineare Algebra f r Ingenieure Eigenwerte und Eigenvektoren E Chalk recording winter term 2003 04 http
177. for some older Maple versions as they only allow to plot in JPEG format where transparency is unavailable To evaluate the mathematical terms identified by the handwriting recogni tion without Mathematica being available a simple calculator program is part of E Chalk as an Evaluator It can handle terms with integers and fraction numbers as operands brackets and the operators and exponentia tion A student has extended this calculator to handle function calls definitions of function constants and basic function plots for two and three dimensions see Figure 4 9 for example output With the E Chalk API it is easy to integrate other computer algebra systems 14GIF images have a color table of up to 256 colors One of the colors can be marked to be fully transparent 15The mathematical handwriting recognition is described in Section 4 9 4 7 BOARD RESOURCE LOADING 75 Plot Sin x y 0 3 0 333 A LIT LITT PEI TP TAN y as ff RAID IRA LTT iy vi Figure 4 9 Example plot from E Chalk s built in computer algebra system like MuPAD or use different ways to connect like using a remote Mathematica server via a TCP socket connection So far only Mathematica and the built in calculator can be used to process the results of the mathematical handwriting recognition In the future the communication between the Evaluators and the handwriting recognition should become part of the API 4 7 3 Decoding When the
178. g a minimum spanning tree con struction and symbol dominance In Josep Llad s and Young Bin Kwon editors Graphics Recognition Recent Advances and Per spectives Fifth International Workshop GREC 2008 Barcelona Catalonia Spain 2003 Selected Papers volume 3088 of Lecture Notes in Computer Science pages 327 338 Springer Verlag 2004 Dennis Tsichritzis Reengineering the university Communications of the ACM 42 6 93 100 1999 Edward R Tufte The cognitive style of PowerPoint Chesire CT USA May 2003 Edward R Tufte Power corrupts PowerPoint corrupts absolutely Wired pages 118 119 September 2003 Vladimir N Vapnik Statistical Learning Theory John Wiley amp Sons New York NY USA 1998 Dan Venolia and Forrest Neiberg T Cube a fast self disclosing pen based alphabet In Proceedings of the conference on Human factors in computing systems CHI pages 265 270 Boston MA USA April 1994 ACM press Guido van Rossum and Fred L Drake Jr Python Language Ref erence Manual Version 2 8 Network Theory Ltd August 2003 W3C Recommendation Synchronized Multimedia integration Lan guage SMIL 1 0 Specification June 1998 W3C Recommendation Synchronized Multimedia integration Lan guage SMIL 2 0 Specification August 2001 Russel Watson An interactive animation architecture for E Chalk Bachelor s thesis Fachbereich Mathematik und Informatik Freie Universitat Berlin September 2004 David J
179. g in management system has been included Figure 6 17 shows a 24The Java connection to the Tablet SDK is based on the work described in Section 6 8 25Speaking of the E Chalk client a major point in usability was to avoid having to install plug ins or any other special viewer software see Section 1 2 On the other hand employing a plug in architecture is not a problem for the server side where the Exymen editor is used The server software needs to be installed anyway and all necessary Exymen plug ins are installed automatically by the E Chalk server installer The 124 CHAPTER 6 TOOLS CONVERTERS ADD ONS Figure 6 17 Exymen being used to edit three E Chalk streams video audio and board The streams are shown at the bottom along a timeline At the upper left the state of the board for the timeline s cursor position is visible The frames at the top right and middle right show the video and the audio signal curve for the same time Figure from Fri02b screenshot of the editor 6 13 1 Plug in Management Programs using plug ins often irritate their users by consuming a lot of time for loading the plug ins on each startup even if the plug in is not needed for the current session Also many applications require a restart of the application or even worse of the operating system when new plug ins have been installed Exymen avoids these problems by using a solut
180. g is also replaced in E Chalk if it runs with a Java version lower than 1 4 to improve user messages in case of a resource access The progress cannot always be determined numerically For example if a task for loading a file from a URL is still waiting for the connection to the remote server there is no way to tell how long it has to wait In these cases the dialog displays an indeterminate progress bar 10GET arguments cannot only be specified for the CGI requests but also for any other URL loading request as they are encoded within the URL see FGM 97 FGM 99 11So far this speed was only tested in JRE 1 2 12For Java 1 3 it also fixes a bug that prevents the specification of an alternative port in FTP URLs see Java bug 4320992 43 In Java 1 4 this problem no longer occurs CHAPTER 4 BOARD SERVER 72 resource request CGI call add image add Applet evaluator call handwriting recognition add chalklet add macro UrlLoad Evaluation Request AppletDef Decoder Applet AppletHandler HtmlTextDecoder TextDecoder TextHandler ResourceHandler ResourceAccessor ImageDecoder Image ImageHandler ResourceDecoder chalklet bookmark ChalkletLoad ChalkletKit y parameters macro bookmark ChalkletHandler MacroHandler Figure 4 6 Overview of resource loading classes 4 7 BOARD RESOURCE LOADING 73 Pl Echalk Au
181. g speed being slowed down 5 times As to improvement suggestions a demand for a higher screen resolution 8 4 STUDIES DURING WINTER TERM 2003 04 161 45 40 m traditional chalk board 35 D PowerPoint Ofoils 30 25 20 15 10 A A 0 T clearly rather equivalent rather clearly inferior inferior superior superior Figure 8 18 Students opinions on teaching with E Chalk compared to using other types of lecturing tools to traditional chalkboards to PowerPoint and to overhead slides appeared again 14 times Training for instructors on using E Chalk was re quested 9 times and a few features have already been considered for future work like a marker tool requested 2 times a feature for using backgrounds like lined and grid paper 4 times and transmission of the cursor 4 times Handwriting recognition which is already integrated for some purposes and is planned to completely replace the need of the keyboard for all E Chalk controls in the future was the most common request 21 times Almost all additional commentaries were requests for features which were already fully supported but not used in the evaluated lecture like changing colors used 11 times for example switching to a dark gray background de mands that instructors use or increase their usage of images animations and Applets 8 tim
182. h the stub serve as interface between the Applet and the browser it is running in For example the Applet accesses its parameters and any other Applet on the same Web site through these classes 7 Therefore E Chalk pro vides its own AppletStub and AppletContext classes for the Applets to run with Actually E Chalk has two classes implementing the AppletContext inter face because Java 1 4 made a change to the interface which is not backward compatible to Java 1 1 In 1 4 the two methods getStream and setStream where added to the interface Unfortunately a Java 1 4 compatible implementation of the interface will cause an exception when loaded in a Java 1 1 environment with JIT just in time compiling The JIT compiler looks at all the classes methods including the new ones which use the class java io InputStream in their signatures Because this class is not available in Java before 1 2 the process will fail Using such a class will cause the exception even in code parts not run due conditional execution To be able to provide an AppletContext to the JVM on both the server side running on 1 4 and the client side which may run in any Java version from 1 1 on the appropriate AppletContext is loaded dynamically utilizing reflection and therefore preventing the JVM from JIT compilation of an inapplicable class After the AppletStub is set the init method of the Applet is called where all the initializations depending on parameters shou
183. hable s init method with arguments These arguments are handled exactly like the command line parameters for E Chalk being executed as an application see Section 3 1 Parameters in the form lt key gt lt value gt are used to change the configuration properties Parameters X lt key gt lt value gt are used to modify the recording settings to assign title and target directory and to 21See part on Recording in Section 2 4 118 CHAPTER 6 TOOLS CONVERTERS ADD ONS SQL textual control BLOB HTML lecture stream Starts E Chalk Browser 3 Clients Figure 6 10 Communication between browser and database set the recorded streams to board only as well as to disable macro incompatible board actions clear all requests and Applet usage To prevent these settings from being stored in the standard echalk conf file and thus being effective at the next E Chalk start the macro recorder creates a temporary copy of the file and assigns the copy to the Launchable as a settings file through setting the echalk conf property by an init parameter When the user finishes the recording the macro creator dialog opens again with new default values set for title and target directory allowing to record another macro until the user chooses to close 6 10 Automated DB or LMS Storage Already in the early stages of the system s development experimental support for creating repositories of E Chalk recordings was implemented A tool for autom
184. halk application For example the sset command can be used to set a property represented by a GUI input element in the setup dialog changing the input component s value This allows to control all setup dialog s settings from the command line For convenient usage the command line also features a persistent command line history controllable with the up and down arrow keys Calls which are a duplicate of the previous call are not added to the history again The commands are implemented by inheriting from an abstract Command class which declares an abstract method reporting the command name ar gument syntax a short description and a method for actually executing the command with the included arguments The description and the argument syn tax are used by the help command of the console See Listing 3 8 for currently implemented commands On startup of the command line console executes a startup file named conf console rc in the default configuration This is useful to define com mand aliases to output information messages to the user and to immediately start other debugging tools using the Launchable interface described below 30 This is equivalent to duplicate settings being ignored in Unix shells e g histdup prev in the tcsh or HISTCONTROL ignoredups in the bash 3 10 DEBUGGING TOOLS 61 echalk 2004 06 21 15 41 44 Middle Europe Time started by user knipping gt help lt string gt alias lt alias gt
185. he image is omitted from the PDF In this case it did not appear on the board anyway because the board relies on the Java image rendering mechanism too GIF Parsing For GIF images the complete data are parsed by the converter Its color lookup table is extracted and the LZW encoded data are decoded to be flate encoded in the PDF image object As mentioned above the flate encoding usually compresses slightly better than LZW Transparent colors are handled in GIF data If the GIF is a multiple image file only the first one is used for the PDF like it was on the board If the image data is truncated the rest of the image is reconstructed as far as possible if the GIF image uses interlacing the empty pixels are copied from neighboring rows see Figure 6 2 For non interlaced images the data are filled with transparent color if that is available from the color table or with the background color defined in the GIF data See Com87 Com90 for details on the Graphic Interchange Format 6 1 3 Color Conversions The main application of the PDFs is printing When the board s background color was not set to white using the original background color would use a lot of printer toner For this reason the background color in the PDF version is set to white by default In an older version of the PDF converter background color and white were simply exchanged The drawback of this method is that it does not preserve the contrast between drawi
186. he handler would let the user place the text as in the add text action described in Section 2 4 For the time being there is no way to produce such text resources 20The rate of board events sent by the macro thread is restricted to 100 Hz to avoid band width bloats See Section 4 11 1 21 ine drawings that are not drawn by the user like the strokes produced by Chalklets are not collected The stroke forwarding is purely meant for interpreting human drawing actions This also prevents infinite loops that might easily occur if Chalklets are allowed to react to Chalklet s output with drawings 22Similar to an AppletContext for Java Applets the ChalkletContext is the communication interface for a chalklet to its environment it runs in The ChalkletContext for a chalklet is provided when it is built by passing it on as a parameter to the ChalkletKit s chalklet build 78 CHAPTER 4 BOARD SERVER Stroke draw undo redo Request StrokeQueue m Stroke MN text image resource Pa 1 StrokeSender 1 Resource Request Handling 1 evaluation request undo add stroke Chalklet StrokeReceiver Herz StrokeReceiver ChalkletContext Figure 4 11 Communication between the E Chalk board and its stroke listeners the handwriting recognition and active chalklets rc RequestStrokeQueue This queue has an extra thread which takes the line drawing data from the queue and sends them t
187. he value as information channel is much lower Therefore the E Chalk system opted for a low quality low bandwidth solution When the first version of WWV was developed no method to capture video data in pure Java was available FKR02 Instead native interfaces of the video hardware device were used under Linux relying on Video4Linux 2 101 and under Windows interfacing to Microsoft s DirectX 8 0a 62 For efficiency reasons the encoder was also realized as a native implementation Recently the WWV implementation became pure Java utilizing the Java Media Framework JMF 44 to access video data Like the WWR3 audio server the new video server has been developed within the SOPA component architecture described in Section 5 1 1 On startup of the server the system creates a flow graph with video handling SOPA components as graph nodes from a graph description given as an XML file Among other ad vantages this keeps down development efforts to integrate new filters or support other output formats For a description of the buffering strategy used in the WWV client see Section 7 4 Codec The video stream is encoded by a very simple differential frame coder The first frame recorded or sent when a client connects is an I Frame a full image All subsequent frames are difference frames The frames are divided into blocks of 8x8 pixels and only blocks that changed significantly are stored The change is measured as a sum of the
188. ib icons jar icons cgi16 gif lt href gt lt thumbnail gt lt arg post false gt lt prompt gt month year lt prompt gt lt id gt date lt id gt lt arg gt lt entry gt Listing 3 3 Example CGI bookmark entry for a calendar resembling Unix s cal which macros are compatible with the current board setup without having to load the macro itself A third key value pair defines the speed used for replaying the macro For chalklet bookmarks the URL entry is the classpath to the chalklet classes to be loaded Additional key value pairs define the minimum height and width of the chalklet enabling the board to sort out chalklet bookmarks that would not fit on the board the name of the ChalkletKit class to be used to build the chalklet and the parameter values to be passed to the chalklet kit s build method as well as the localized parameter names enabling the board to show a user friendly tooltip see Section 4 5 For providing the user guided interface to set the parameter a ChalkletKit has to define the description of expected pa rameters in the bookmark editor like an EvaluatorKit does for the setup See Section 3 3 for an description of the KitSetupInfo provided by ChalkletKit An excerpt from a chalklet bookmark file is shown in Listing 3 4 3 5 Audio Profiles The list of available audio profiles is stored as an XML file using the same DTD as the bookmarks shown in Listing 3 2 The URLs define the locatio
189. icient to get pleasing page breaks Board content where horizontal cuts as breaks are not adequate due to writ ten lines overlapping vertically cannot be handled well by this method see for example Figure 6 1 A possible strategy to solve this would be to construct a graph of board elements as nodes and edges between touching elements Pages are generated by distributing the elements on the pages so that elements of a 4Drawings in the board background color like eraser actions do not prevent the page break 5While the insertion of the weighted interval may take quadratic run time in the worst case the implementation used in the converter runs in near linear time for real world lecture data It uses the fact that almost all board elements have only a small y offset from the previously generated element Using the previous insertion position as start position for searching the next position results in a drastic speedup 6 1 EXPORT TO PDF 107 She Koupmanln ons 2 er Valter Bonorgirt pent sim 1 AS 1 din Kamp ou vom amp Bop t n 2 Xp cooler galon PISE Elan a Figure 6 1 Handwritten lines that contain vertical overlay either due to a sloped baseline or to high ascents or low descents running into neighboring lines prevent straightforward page breaks using horizontal demarcation lines Descender lines are plotted in light gray connected graph component appear on the same page whenever possible
190. igure from Fri02a sequences of dependent events The MediaEditor for the board stream not only allows recording new chunks and replay of the stream It also lets the user insert scroll events and apply other spatial editing operations Users may select rectangular board sections for cut copy and paste operations as well as for moving the selected elements by dragging They may also remove vertical intervals from the board see for example Figure 6 20 27 A coarse separation into atoms would seriously constrain the editing facilities on board data Fortunately the atoms are almost always single strokes Only interactions with Applets and undo redo operations can create longer atoms 128 CHAPTER 6 TOOLS CONVERTERS ADD ONS Chapter 7 Client Applets A recorded E Chalk lecture is replayed by Applets When the remote user opens the lecture s Web site one Applet per transmitted data stream is opened a board Applet an audio Applet and a video Applet or any subset of these three if not all of the streams were recorded The same Applets are used for live transmission and replay of archived lectures only the Applet parameters given in the Web page differ If the transmission is live each client Applet opens a TCP socket connections to the E Chalk server and read the data from this connection to display the current lecture data For replay from an archive an additional Applet is opened The control panel Applet provides VCR ope
191. imestamp Form Image id r y with the image itself is stored in the file images id dat in the lecture session directory The id parts are created as ascending decimal numbers but the event file parsers do not rely on this Applets and Applets Events An Applet with x y being the position of the upper left corner is represented as timestamp Form Applet id x y with the HTML file containing the definition being stored as applets id html Again the file names are created as ascending decimal numbers Input events on Applets are also encoded The event timestamp AppletEvent Mouse n id mod r y clicks popupl comp encodes a mouse or mouse motion event for the Applet internally numbered n The integer entry id is the Java event identifier for distinguishing between mouse pressed mouse released mouse moved etc and mod is the integer modifier key mask for Shift Ctrl Alt and or Meta key down The values x y give the position of the mouse event in its triggering component clicks is the click count for this event for example for identifying double clicks and popup is true or false marking the mouse event as a pop up trigger on the platform where the event was created The originating component is encoded by a trailing list of indices the sequence no nz_1 nz means the event is on the nzth subcomponent of the n _ th subcomponent etc of the noth subcomponent of the Applet If the list is empty the mouse event is on the Ap
192. in the key must be escaped as unescaped spaces separate property keys from entries See Listing 3 7 for a complete listing of the program s command line options The command line application echalk tools 110n KeyCmp prints a Unix diff style difference between the keys in a single property file and the set of keys from a list of property files see Listing 3 7 This allows to conveniently check the keys from all the property files for a single locale against a list of all keys from the source code generated by the GrepTxtCall tool The combination thus provides a static check of the resource bundle entries against the localization calls in the program 3 10 Debugging Tools 3 10 1 E Chalk Command Line Console For debugging purposes a command line interpreter was added to E Chalk which can be run at the same time as the main system It shows all outputs the package name 29GrepTxtCall is able to parse keys like Reading file 0 failed and assemble them to a single string It can also handle bracketed expressions 60 CHAPTER 3 THE E CHALK APPLICATION Echalk Console Figure 3 4 The command line console listing the threads during recording from the standard out and error streams and provides a number of commands to control the application Commands provided include instructions to list and modify the running Java threads see for example Figure 3 4 as well as instructions to access the property settings of the E C
193. ine courses using E Chalk were evaluated at Freie Universit t Berlin and Tech nische Universit t Berlin in the winter term of 2003 04 A total of 303 ques tionnaires were returned by students Table 8 4 shows details on the type of the courses and the number of returned questionnaires At TU the lectures were given in the auditorium shown in Figure 8 2 The lecturer wrote on a digitizer tablet with built in LCD screen The screen was projected for the audience to read As the auditorium was still not set up for audio recording in that term only board stream recording and PDF script generation were provided on the Web The seminars and tutorial courses at FU were held in a seminar room with a rear projector see Figure 8 4 The exercise courses recorded board and audio and made the replay available for Web access together with the PDF transcripts For the three cartography seminars E Chalk was exclusively used for classroom teaching No recordings were made available for distance teaching In class a number of digitizer tables at the students desks were used to allow the students to work on the screen from their seats The instructor used this to promote interactivity in his seminar Without any E Chalk materials being published for these seminars all questions on remote usage were omitted in their questionnaires None of the nine evaluated courses offered live transmission of the class Main Findings About 44 of the students reported usi
194. ing Wolf Ulrich Raffel and Gerald Fried land Elektronische Kreide Eine Java Multimedia Tafel f r den Pr senz und Fernunterricht Informatik Forschung und Entwick lung 16 159 168 September 2001 Ra l Rojas Lars Knipping Wolf Ulrich Raffel and Gerald Fried land Elektronische Kreide Eine Java Multimedia Tafel fiir den Pr senz und Fernunterricht In Tagungsband der Learntec vol ume 2 pages 533 539 Karlsruhe Germany October 2001 Dave Raggett Arnaud Le Hors and Ian Jacobs RFC 1866 Hy pertext Markup Language 4 0 W3C Recommendation April 1998 Tristan Richardson Quentin Stafford Fraser Kenneth R Wood and Andy Hopper Virtual network computing IEEE Internet Computing 2 1 33 38 1998 Matt Ratto Ryan Benjamin Shapiro Tan Minh Truong and William G Griswold The ActiveClass project Experiments in BIBLIOGRAPHY 185 SAHS04 SASO1 Sau98 Sch03 Sez01 SFR96 SGH 94 SGH98 SGH 99 encouraging classroom participation In Proceedings of the Com puter Support for Collaborative Learning CSCL 2003 Bergen Norway June 2003 Beth Simon Ruth Anderson Crystal Hoyer and Jonathan Su Preliminary experiences with a tablet PC based system to support active learning in computer science courses In Proceedings of the ninth annual conference on innovation and technology in computer science education ITiCSE Leeds UK June 2004 Lisa Stifelman Barry Arons and Chris Sch
195. into the text editor On hitting OK the settings are stored and the lecture recording starts Cancel can be used to discard any changed the Exit button stores the changes and closes the session without starting to record Each tabbed page of the setup dialog features a Help button which starts a built in browser on the page s help section of the system s HTML documenta tion Board Settings The settings controlled with the board page control the size and background color of the board see Figure 2 4 The width and height values accepted by 10See Section 3 2 for details on the format 34 CHAPTER 2 USER INTERFACE El Echalk Extended Board Options Initial Values El Echalk i Cnaiksize O iz General A Boara audio viese Server Spor la Eraser Size O o 4 T 10243 esta Size Width 1024 Hei 768 Auti O al emi 768 3 Auto Font Size Aal I Background ll Black y Chalk Color Green y Applets Images m Computing Server Select Computing Server to Activate 20 Bookmarks 3 Cols IR gt Macros Edit CGI Bookmarks arc Mathematica None Maple Properties Other Settings Handwriting Recognition for Magenta Scrollbar ox cancel Help Figure 2 4 Left The board settings page Right Dialog for extended board options shown from the board s page with the More button the dialog are bound to the displ
196. ion ITSE 1 1 9 20 February 2004 Gerald Friedland Lars Knipping and Ernesto Tapia Web based lectures produced by AI supported classroom teaching Interna tional Journal of Artificial Intelligence Tools IJAIT 13 2 367 382 2004 Gerald Friedland and Tobias Lasser World Wide Radio Au dio Live Ubertragung durch das Internet Technical report Bun deswettbewerb Jugend forscht e V Hamburg Germany 1998 Gerald Friedland and Karl Pauls SOPA self organizing process ing and streaming architecture Technical Report B 04 13 Institut fiir Informatik Freie Universitat Berlin August 2004 176 Fri02a Fri02b Gat03 GD96 Gei98 GHJV95 GM93 GM96 GMWo1 Gol97 GSWo01 BIBLIOGRAPHY Gerald Friedland Towards a generic cross platform media edi tor An editing tool for e chalk Diploma s thesis Fachbereich Mathematik und Informatik Freie Universit t Berlin May 2002 Gerald Friedland Towards a generic cross platform media edi tor An editing tool for e chalk abstract In Proceedings of the fourth Informatiktage 2002 Bad Schussenried Gesellschaft fiir In formatik e V November 2002 Bill and Melinda Gates Foundation Access for the vision impaired April 2003 Mark D Gross and Ellen Yi Luen Do Ambiguous intentions a paper like interface for creative design In Proceedings of the ninth Annual Symposium on User Interface Software and Technology UIST pages 183
197. ion based on an open source implementation of the OSGi standard named Oscar 70 While the OSGi standard was originally conceived for component management in the field of Ubiquitous Computing it is also suited for desktop applications Having been developed for small mobile devices it was designed to be small compact and efficient It allows the editor to install and update plug ins via the Internet or remove installed ones all while the application runs and without requiring a restart Plug ins can also manage themselves for handling version updates or in stalling other plug ins For example if an Exymen format handler encounters an unknown data format it may search for a plug in to handle it install the plug in and let it loose on the data Plug ins may also extend other plug ins providing a kind of modular construction system The Oscar OSGi system takes care of all resulting dependencies On shutdown all plug in states are stored to plug in mechanism is effectively hidden from the standard E Chalk user The same holds true for the SOPA plug in architecture underlying the audio and video server components In both cases the plug in architecture is only relevant for developers extending E Chalk 6 13 POST PRODUCTION WITH EXYMEN 125 Sponge Scrollevent Figure 6 18 Board chunk visualization and explanatory legend Figure from Fri02a provide for fast system startup without checking the dependencies again Download
198. ion for Learning Electronically http manic cs umass edu research html Peter Marshall AudioGraph Online Lecture on DC Motors http www ee surrey ac uk Teaching Courses DCMotors Microsoft DirectX http www microsoft com directx Microsoft Tablet PC Developer Center http msdn microsoft com mobility prodtechinfo platforns WEB REFERENCES 195 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 MOSES Mobile Service for Students http www moses tu berlin de MuPAD research group of Universitat Paderborn http www mupad de MuPAD SciFace Software http www mupad com Netpbm http netpbm sourceforge net Microsoft Developer Network Official Guidelines for User Interface Developers and Designers http msdn microsoft com library en us dnwue htm1 welcome asp Numonics Inc http www numonics com OSCAR Richard Hall s Open Service Container Architecture http oscar osgi sourcefourge net OSGi Open Service Gateway Initiative http www osgi org PalmOne http www palmone com Panasonic Panaboard from Kintronics http www kintronics com panaboard html PhatWare Corp Paragraph Inc http www paragraph com PLATO Programmed Logic for Automated Teaching Operations http www plato com PolyVision Visual Communications http www polyvision com Promethean Interactive Whiteboards http www prom
199. iong Liu Yong Rui Anoop Gupta and J J Cadiz Automating camera management for lecture room environments In Proceed ings of the conference on Human factors in computing systems CHI pages 442 449 Seattle WA USA March April 2001 ACM press Gordon E Legge Gary S Rubin Denis G Pelli and Mary M Schleske Psychophysics of reading ii low vision Vision Research 25 2 253 266 1985 Hsi Jian Lee and Jiumn Shine Wang Design of a mathemati cal expression understanding system Pattern Recognition Letters 18 3 289 298 1997 Jennifer Mankoff and Gregory D Abowd Cirrin a word level unistroke keyboard for pen input In Proceedings of the eleventh annual ACM symposium on User interface software and technol ogy UIST pages 213 214 San Francisco CA USA November 1998 ACM press Klaus Manhart H rfunk im Internet Funkschau 25 42 44 November 1999 Nicholas E Matsakis Recognition of handwritten mathematical expressions Master s thesis Massachusetts Institute of Technol ogy May 1999 BIBLIOGRAPHY 181 MCvM97 MCvMK95 MGH 97 MHJ 95 MIEL99 MIELOO MNO2 MO02 Mom91 Mon86 MS99 Thomas P Moran Patrick Chiu and William van Melle Pen based interaction techniques for organizing material on an elec tronic whiteboard In Proceedings of the tenth annual ACM sym posium on User interface software and technology UIST pages 45 54 Banff Canada October 1997 ACM p
200. ition pages 515 519 August 1996 Andrew Sears Doreen Revis Janet Swatski Rob Crittenden and Ben Shneiderman Investigating touchscreen typing the effect of keyboard size on typing speed Behaviour and Information Technology 12 1 17 22 1993 Mia Stern Jesse Steinberg Hu Imm Lee Jitendra Padhye and James F Kurose MANIC Multimedia asynchronous networked individualized courseware In Proceedings of World Conference on Educational Multimedia and Hypermedia ED MEDIA Calgary Canada June 1997 Richard M Stallman Emacs the extensible customizable self documenting display editor In Proceedings of the ACM SIGPLAN SIGOA symposium on Text manipulation pages 147 156 Port land OR USA 1981 ACM press Henrik Steffien Handschriftliche Erstellung und Ausf hrung von Python Skripten auf der E Kreide Tafel Bachelor s thesis Fach bereich Mathematik und Informatik Freie Universit t Berlin September 2004 Lisa Joy Stifelman Augmenting real world objects A paper based audio notebook In Michael J Tauber Victoria Bellotti Robin Jef fries Jock D Mackinlay and Jakob Nielsen editors Proceedings of the Conference on Human Factors and Computing Systems CHI pages 199 200 Vancouver Canada April 1996 ACM Press Lisa Joy Stifelman The Audio Notebook Paper and Pen Inter action with Structured Speech PhD thesis School of Architec ture and Planning Massachusetts Institute of Technology August 1997 Norbe
201. ixer channels thus work like expander compressor limiter components used in recording studios 100 CHAPTER 5 AUDIO AND VIDEO SERVERS Figure 5 7 Three seconds of a speech signal with a 100 Hz sine like humming before light gray and after filtering dark gray removes any humming caused by electrical interference Because the frequency and shape of the humming might change during a lecture multiple noise fin gerprints can be specified The best match is subtracted Bol79 See Figure 5 7 for an example It is not always possible to pre record the humming but if so this method is superior to using electrical filters which have to be fine tuned for a specific frequency range and often remove signal data more than is desirable Finally Equalizer settings are applied before the normalized signal is pro cessed by the codec As noted above filtering also results in more efficient compression Because noise and overflows are reduced entropy also scales down and the compression can achieve better results In addition to controlling the signal for recording the system checks the signal from the soundcard for the floor noise of the microphone If the floor noise becomes significantly lower than expected according to the audio profile it is likely that a problem occurred Batteries of a wireless microphone may be running low or the plug might been accidently pulled from the soundcard or the lecturer might simply have forgotten to swit
202. ization is dat echalk meaning the property files are named dat echalk_de properties for the German locale dat echalk_es properties for the Spanish locale etc This resource bundle only contains a list of bundles to be loaded with different bundles for different contexts For example one resource bundle contains all error messages and another bundle contains all labels occurring in the E Chalk GUI When the same key appears in more than one resource bundle already loaded a warning is printed to the error stream see Section 3 10 2 One special resource bundle is initially empty in the standard E Chalk in stallation the bundle etc usertexts is installed as files in the directory etc While the other resource bundles are packed into Jar archives the property files for etc usertexts can be directly modified with a text editor allowing users who want to plug in their own components to the E Chalk system to easily add their own localizations to the E Chalk localization resources and use the Txt class for their components 25 Java s loading strategy for loading the resource bundles uses the most specific available match for the defined locale in the applications classpath For example for a locale named de_DE_EURO the language German for the country Germany in the variant with Euro currency symbol the bundles for de_DE_EURO are searched for first If they cannot be found bundles for de_DE will be loaded Failing this de bundles are l
203. ized The class loading process also stores all class data in the Applet resource directory See Section 4 10 1 for further details 4 7 4 Chalklets When the user selects a chalklet bookmark the ChalkletKit referenced by the bookmark is loaded as a resource load task To access the kit class from the class path URL the loading process uses the java net URLClassLoader and Java reflection The ChalkletKit is asked for the minimum area size its chalk lets need Next the echalk board rc ChalkletHandler lets the user select the board area the chalklet should live in as described in Section 2 4 2 The construction of the concrete chalklet instance is done in the handler following the area selection because the user selected board area is needed in a param eter to the chalklet building method In addition to the parameters given by the chalklet bookmark the factory is passed a echalk board rc Chalklet Context instance which serves as a communications interface between chalklet and board The ChalkletContext can be queried about information on the environment the chalklet lives in for example the location of the chalklet area and the background color of the board and provides methods for the chalklet to send stroke paintings to the board When the chalklet instance is constructed its area is outlined in gray on the board and it is registered as a stroke listener to user strokes drawn in its area See Section 4 8 1 for a detailed description of
204. java text MessageFormat see 39 for details A problem introduced by dynamic localization is that lookup of keys cannot be statically checked by the Java compiler Localization fails at runtime if the key is missing in the resource bundles for example due to a typing error Flaws in localization have to be identified by test runs but reaching a complete code coverage is difficult especially for localized error messages which are accessed only in exceptional cases To address this problem some tools have been developed for static checks described below In addition a fallback mechanism is used The localization used by E Chalk are the English strings to be displayed When a lookup for a key fails the failure is written to the error log and the key itself is used As a result the user gets the English version displayed instead of some cryptic internal messages or blank field The drawback of using the English versions as keys is that there cannot be different localized texts where the English locale uses identical texts This may be undesirable for translations which differ according to context The GrepTxtCall command line application from the echalk tools 110n package scans for all keys used in calls to the Txt get methods and lists 27See Section 3 10 2 for the error message logging mechanism 28 ocalization is often abbreviated with L1ON and internationalization with 118N hence 3 10 DEBUGGING TOOLS 59 gt java echalk
205. ld be made by the Applet 8 Then the Applet is placed by the user on the board and added as a compo nent to the boards DrawPanel see Section 4 4 The Applet s position and size are set by calling the Applet s setBounds java awt Rectangle method The Applet s execution begins by calling its start method after adding a number 27 A distinct AppletStub instance is used for each Applet running in a browser while an instance of AppletContex exists for each HTML page with Applets The Applets parameter are accessible through the stub and the other Applets can be communicated with through the context 28 These cannot be done in the constructor because at that time an Applet has no access to parameters via the AppletStub 4 10 APPLET CONTROL 83 for all Applet definitions from HTML page load given Applet class c instantiate c with default constructor construct AppletContex with access to all Applets instances for all Applets a construct AppletStup s from definition and context call a setStub s for all Applets a call a init for all Applets user places Applet a on board to Rectangle r call dp add a for DrawPanel dp call a setBounds r for all Applets a call a start in a new thread Listing 4 1 Steps to initialize a number of Applets given in an HTML page of event listeners to be able to record the lecturer s interaction with the Applet see below For multiple Applets from a single HTML page each of these steps has to
206. led July 21 1998 180 Kra94 Kru05 KSBM99 LEW 02 Liw04 LNHL00 LRGCO1 LRPSS5 LW97 MA98 Man99 Mat99 BIBLIOGRAPHY Axel Kramer Translucent patches dissolving windows In Proceedings of the seventh Annual Symposium on User Interface Software and Technology UIST pages 121 130 Marina del Rey CA USA November 1994 ACM press Olga Krupina Client Server Architecture for a Neural Simulation Tool PhD thesis Fachbereich Mathematik und Informatik Freie Universit t Berlin 2005 To appear S Sathiya Keerthi Shirish K Shevade Chiranjib Bhattacharyya and K R K Murthy Improvements to Platt s SMO algorithm for SVM classifier design Technical Report CD 99 14 Control Division Department of Mechanical and Production Engeneering National University of Singapore Singapore 1999 Marc Loy Robert Eckstein Dave Wood James Elliot and Brian Cole Java Swing O Reilly second edition November 2002 Marcus Liwicki Erkennung und Simulation von logischen Schal tungen f r E Chalk Diploma s thesis Fachbereich Mathematik und Informatik Freie Universit t Berlin March 2004 James Lin Mark W Newman Jason I Hong and James A Lan day DENIM finding a tighter fit between tools and practice for web site design In Proceedings of the Conference on Human Fac tors in Computing Systems CHI pages 510 517 The Hague The Netherlands April 2000 ACM press Q
207. lename gt relative to lt lecture dir gt pdf Key value pairs for debugging purposes pdf grabjfifs truelfalse pdf grabgifs true false pdf bin2ascii85 truelfalse pdf noflate true false echalk debug true false Listing 6 1 The board to PDF converter program prints a summary when called without arguments simply split the data into pages at fixed offsets The distribution of page breaks has depended only on the PDF output paper format not on the content The present algorithm uses a greedy strategy It tries to place the next break as a horizontal cut with as much content as possible put onto the page while no visible board element is being cut If no such page break is found which uses at least the upper two thirds of the page for content and a kind of minimal cut is searched for in the lower third of the page This is realized by computing the amount of ink weight of the content by the vertical coordinate Each visible elementary drawing a line segment an image a typed text adds its width to the y interval of its vertical extension A weighted partition is generated of the y interval 0 oo represented as a list of weighted intervals The weight of each interval is a measure of how much board content is cut by a horizontal page break which lies in the interval The weight gives only an approximation as overdrawings and the rounded caps and joints of line strokes are not taken into account but in most cases this is suff
208. load task needs more than half a second and the dialog also provides a cancel action for the task Canceling a load task is not easily done it is not possible for example to abort a read from a URL immediately As long as the thread is IO bound it cannot process the message to stop As a workaround the thread is not only sent a signal to die but it is also marked as invalid so that any resulting data are discarded For efficiency reasons not every task creates a new thread Instead the loading thread is reused except when the user selects to cancel the loading task In the latter case a new thread is created to ensure that the user can immediately start a new resource loading task This means the RcLoader is implemented according to the thread pool pattern GHJV95 but with only a single worker thread being in the pool Resource requests are composed of two subtasks represented in an abstract class named echalk board rc Task First the raw resource data are loaded like for example getting data of an image from its URL In the second step the loaded data is decoded to an object that can be handled by the board i e the image byte data has to be converted to a Java Image object After that the image is passed on to a handler object which knows how to add the resource to the board For example the ImageHandler lets the user select the position of Responding to user input is done in the event handler thread Having a longer
209. lso possible for client boards with a horizontal extension smaller than those of the server This can happen when the client screen has a smaller resolution or because the remote user resized the board For vertical scrolls the client has two possible sources the user drags or the transmitted scrolls from the lecturer at the server board By default the client combines the two always using the last defined scroll offset regardless of it source This implementation assumes the standard case of the remote viewer looking at the board section the teacher uses for the given lecture portion while still allowing them to peek at older portions 8See Section 2 4 The only exception are the areas of embedded Applets because the Applets consume those mouse drags themselves 134 CHAPTER 7 CLIENT APPLETS Figure 7 5 Board client with context menu A pop up menu in the client allows the user to change the mode of han dling scrolls The behavior may be changed to handle only user drags or only transmitted scrolls see Figure 7 5 7 2 4 Handling Applets The Applets are managed basically in the same way as described in Section 4 9 apart from recording facilities which are obviously not available at the client side The local user can interact with the Applet regularly While this can be used as a feature for adding interactive elements to a lecture this is a major problem one wants a close reproduction of the live lecture as the rem
210. m relies on flow menus a variant of pie menus GW00 GMW01 2 The advantage of flow menus is that they avoid the necessity of visual feedback once learned as stroke gestures by the user and thus reduce the cognitive involvement in submitting the commands Another concept used is the typed drag and drop where board objects can be assigned types to determine their behavior when dropped onto another typed object The interface allows continuous freehand scaling and all actions are logged to supply an infinite undo mechanism Visual snapshots can be taken GSWO1 Applications developed for testing the concepts are a brainstorming tool called PostBrainstorm Gui02 and the Geometers Workbench GWW00 for differential geometry by informal sketching using Wolfram Mathematica for the calcula tions 1 5 7 Other CSCW Systems DOLPHIN SGH 94 is a system to capture informal work group meetings supporting synchronous and asynchronous settings It manages both shared and private documents Text images handwriting and audio can be transmitted 20See Section 1 4 for a short description on pie and flow menus 16 CHAPTER 1 INTRODUCTION AND RELATED WORK synchronously Asynchronous access to a meeting s documents is allowed but the interaction is not recorded for replay Coral MHJ 95 is a confederation of tools to support real time capture and replay of free form meetings It captures materials shown on the whiteboard including freehand
211. mandt The audio notebook paper and pen interaction with structured speech In Proceedings of the conference on Human factors in computing sys tems CHI pages 182 189 Seattle WA USA March April 2001 ACM Press Eric Saund Image mosaicing and a diagrammatic user interface for an office whiteboard scanner Technical report Xerox Palo Alto Research Center 1998 Joachim Schulte Evaluation des Einsatzes der Software E Kreide in der universit ren Lehre Magister s thesis Technische Univer sit t Berlin Institut f r Sprache und Kommunikation November 2003 Metin Sezgin Feature point detection and curve approximation for early processing of free hand sketches Master s thesis Mas sachusetts Institute of Technology May 2001 Quentin Stafford Fraser and Peter Robinson BrightBoard A video augmented environment In Michael J Tauber Victoria Bellotti Robin Jeffries Jock D Mackinlay and Jakob Nielsen ed itors Proceedings of the Conference on Human Factors and Com puting Systems CHI pages 134 141 Vancouver Canada April 1996 ACM Press Norbert A Streitz J rg Gei ler Torsten Holmer J rg M Haake and Jeroen Hol DOLPHIN integrated meeting support across lo cal and remote desktop environments and liveboards In Proceed ings of the ACM conference on Computer supported cooperative work CSCW pages 345 358 Chapel Hill NC USA October 1994 ACM Press Norbert A Streitz J rg Gei ler and Torsten
212. maries capturing the essence of the lectured material in their own words TA99 1 3 Board Hardware When using the E Chalk system the instructor needs to have some kind of electronic pen input device and a display for the audience In situations where the hardware needs to be portable a Tablet PC with a data projector to display the computer screen for the class is a viable option Alternatively digitizer tablets can be used The tablets come in a broad range of variants including tablets with integrated LCD screen 104 greatly easing the required hand eye coordination in writing and drawing Both Tablet PCs and digitizer tablets track the pen using electrical induction An early example of digitizer tablets which even used the chalkboard meta phor is shown in 1 3 The first commercially available notebook sized computer with integrated input pen was the GRiDPad from GRiD Systems released in September 1989 Its operating system was based on MS DOS In 1991 another tablet computer the Momenta Pentop Mom91 from Go Corporation became available this time with a dedicated operating system called PenPoint These early examples were commercial failures suffering from available handwriting recognition not being sufficient for user requirements and from the product s high cost and weight The Momenta for example weighed seven pounds and had a purchase price of about 5 000 So pen computers beyond PDA size did 8 CHAPTER 1 INTRODUC
213. markings and the audio stream The transBOARD IU97 is a physical whiteboard with pen tracking based on infrared laser scanning Remote users can view whiteboard activity both synchronously and asynchronously via a Java Applet The CSCW system described in Rek98 combines one PalmPilot PDA per user and a single shared whiteboard The Palms called M Pad by the authors serve as tool palette and data entry palette for the whiteboard implementing an oil painters palette and easel metaphor NotePals DLC 99 is a note sharing system for work groups running on PalmPilots It records timestamped handwritten notes and adds some context information the name of the author and the project name In an optional post processing step pattern recognition is applied to the notes to support additional retrieval methods See Figure 1 9 DUMMBO dynamic ubiquitous mobile meeting board is intended to cap ture informal meetings It records board history and audio as WAV The record ing starts automatically when more than two people gather at the board or when somebody starts to write or erase on the whiteboard BAT99 DSA01 1 6 Course Authoring Systems Course authoring systems are tools for the non live development of e learning material A number of authoring systems for general HTML page building or for interactive multimedia applications are often used for generating e learning modules Commercial examples of the first type include Microsoft Frontpag
214. mathematical hand writing recognition was included in the E Chalk board right from the very begin ning as an interface to the computer algebra systems see RKRF0la RKRFO1b 23 An interface for MuPAD by SciFace 65 66 is under development A built in system for calculator type requests and plotting of simple one and two dimensional functions has also been written The current implementations for Maple and Mathematica require a locally installed algebra system but it would be easily possible to use a remote server 24See Section 2 4 1 for bookmarking CGI can only be accessed by bookmarks as the CGI parameters to be sent over must be declared in advance 25Prompting texts are set in the CGI bookmark editor 42 CHAPTER 2 USER INTERFACE Figure 2 13 Left CGI request parameter prompt text a word user input Kreide and answer from a CGI script using the Leo 52 server Center CGI request prompt 12 digits to a CGI returning a EAN code graphic and its result Right CGI request for a CGI with several parameters with the third parameter not yet entered by the user Figure 2 14 The mathematical handwriting recognition employed on the board The recognized term is printed along with the result from the computer algebra system to give feedback on the recognition result While the early version could only handle simple arithmetic expressions it has now moved to more complex mathematical formulas FKRT03
215. me term at the FU Berlin Computer Science department but differing in the teaching technique One course was taught with E Chalk the other with a traditional blackboard The E Chalk recordings included audio and were made available on the Web for remote access The students were given the standardized VBVOR Die98 questionnaire to get their opinions on the course s quality In each courses 20 questionnaires were returned The results FKR 04b of this study yield favorable findings on E Chalk The statement In my opinion the topic of the course is very expedient in the context of my study received a higher agreement in the E Chalk course and the statement Too much content was covered in the course received less agreement with E Chalk Asked how often they attended the classes there was also a tendency to reduced presence in the E Chalk classes This result which might be judged favorably or not is very likely a consequence of the supplied 8 4 STUDIES DURING WINTER TERM 2003 04 155 course in uni question type title structor versity naires lecture linear algebra A TU 127 lecture linear algebra B TU 37 lecture computer oriented mathematics C TU 65 exercise design amp analysis of algorithms D FU 11 exercise design amp analysis of algorithms E FU 16 exercise design amp analysis of algorithms F FU 9 seminar cartography G FU 10 seminar cartography G FU 15 seminar cartograph
216. milar to hovering mouse cursor and when the pen is pressed down for writing similar to a mouse drag Many also feature an extra button on the pen allowing to emulate a second mouse button With the products Mimio 102 and EBeam 21 one can turn regular white boards into digitizing ones The product is compromised of sheaths for normal whiteboard pens and sensors to be attached to the whiteboard by vacuum cups When the pens are pressed down for writing they are located on the board by a combination of ultrasonic and infrared signals In early experiments of the E Chalk project with Mimio the device exhibited observable delay too large for it to be conveniently used in combination with a front projection 15 The SmartBoard products from Smart Technologies 88 include both front and rear projected systems Their pen input is based on touch technologies registering pressure on a touch sensitive film by measuring changes in the elec trical resistance A finger can be used instead of a pen but the input system does not distinguish between a mouse drag and a mouse move The SmartBoard handles several colors of writers and an eraser tool This is done by trays to keep the writing tools in The system assumes the writing tool to be used for which the associated tray is empty When the user holds a pen in each hand or puts a pen in the wrong tray things can quickly become confusing PolyVision Visual Communications 76 Webster LT Series uses
217. mond and Randall Davis Tahuti A geometrical sketch recognition system for uml class diagrams In Tom Stahovich James Landay and Randall Davis editors Papers from 2002 AAAI Spring Symposium on Sketch Understanding pages 59 66 Palo Alto CA USA March 2002 AAAI Press Technical Report 55 02 08 Tracy Hammond and Randall Davis LADDER A language to describe drawing display and editing in sketch recognition In Proceedings of the Eighteenth International Joint Conference on Artificial Intelligence IJCAI pages 461 467 Acapulco Mexico August 2003 Morgan Kaufmann Publishers Tracy Hammond and Randall Davis Automatically transform ing symbolic shape descriptions for use in sketch recognition In Proceedings of the Nineteenth National Conference on Artificial Intelligence AAAI pages 450 456 Pittsburgh PA USA July 2004 Norman Hendrich HADES The Hamburg design system In EASA 98 European Academic Software Award Alt C Confer ence Lifelong Learning on a Connected Plane Oxford UK September 1998 178 HK98 HKWO2 HLOO HLLMO2 Hop91 H r03 TELMOO IMEL99 Int88 Int90 BIBLIOGRAPHY Sowon Hahn and Arthur F Kramer Further evidence for the division of attention among non contiguous locations Visual Cog nition 5 1 2 217 256 1998 Wolfgang H rst Thorsten Kreuzer and Marc Wiesenh tter A qualitative study towards using large vocabulary automatic speech recogniti
218. mote viewers connected ten minutes after the start of the recording they had option to get the lecture recording presented as a replay shifted ten minutes in time compared to the live stream Since this feature was never used by real users it is no longer supported in E Chalk 129 130 CHAPTER 7 CLIENT APPLETS server client E Chalk server browser I i h socket stream to audio data audio Applet 1 L 1 i video data i socket stream to i gt video Applet board event data Socket sirean t0 board Applet Web server loaded by i board resources Applet code loaded by Figure 7 1 Communication between an E Chalk server and a client for live transmissions Board resources include images and data of Applets added to the board 7 1 Client Control Panel and Masi Interface To be able to synchronize the different replay Applets the abstract Applet sub class de echalk applet Masi Media Applet Synchronization Interface was defined and all the content displaying Applets inherit from this class A Masi Applet provides methods which report the capabilities for navigation in time like can jump forward can jump backward can pause and the current replay status like is paused and the current offset in time Also it provides methods for modifying the play status like modifying the play offset or toggle pause mode The control p
219. ms 154 CHAPTER 8 EXPERIENCES AND EVALUATION term questionnaires without without with lecture E Chalk E Chalk E Chalk sum linear algebra for engineers 2001 02 170 222 392 computer oriented mathematics 2001 02 90 66 156 numerics I for engineers 2002 03 39 22 61 differential equations for engineers 2002 03 132 56 188 sum 431 366 797 Table 8 3 Courses and number of returned questionnaires evaluated in the study comparing E Chalk courses during the winter term of 2003 04 with non E Chalk courses of previous winter terms e Traditional chalkboard skills directly translate into skills for good E Chalk lectures e In practice the use of plain drawings and writing predominates Advanced features like the integrated computer algebra system or calling CGI scripts are only rarely used e If audio were recorded with the lecture students made use of both replay and PDF printouts on an equal level 8 4 Studies During Winter Term 2003 04 Three more evaluation studies were performed during winter term of 2003 04 covering E Chalk courses at Freie Universitat Berlin and Technische Universitat Berlin More results of these studies can be found in FKR 04b and FKR 04a 8 4 1 Comparative Studies Two studies compared E Chalk courses to traditional ones In the first of these studies there were exercise courses on the same subject design and analysis of algorithms and held in the sa
220. n 5 1 54 CHAPTER 3 THE E CHALK APPLICATION 3 7 HTML Templates The E Chalk server creates three different kinds of HTML index files in record ing directories First there is an index file for an ongoing recording without live transmission available The HTML file serves to inform remote users about the lecture not being available yet Then there is an HTML file for a live trans mission that embeds the Applets for receiving the transmitted stream board audio and or video and the relevant transmission parameters like which TCP port to listen to Finally there is a page for archived replay embedding the replay Applets of the recorded streams which are the same Applets as those for the live transmission but with different parameters plus an Applet similar to a VCR control Also PDF transcripts of the lecture are linked from this page For these pages to be customizable in advance by the user depending on the lecture parameters they are generated from templates interpreted by the echalk main util TemplateProcessor class The configuration file conf template template conf determines which of the template files is used for which of the three HTML files the character encoding used by the template and the names of the HTML files to produce The character encoding property allows the use of localized templates with managed character sets for example when using a Korean locale Also source and target name of the Applet s client Jar
221. n editing tool named AOFedit is available for Unix The AOF system also features a number of other tools for preprocessing like the PowerPoint importer application ppt2aof and for post processing like the indexing tool aofSE 1 8 7 Lecturnity Lecturnity 50 is a commercial lecture recording tool by imc Advanced Learning Solutions 37 written in Java and run on Windows The Lecturnity Assistant uses MS PowerPoint slides and images BMP GIF JPEG as the basis of a slide recording to be captured with annotations The presentation can also use a screen grabbing functionality Annotation tools include pointer marks freehand drawing tool a highlight tool and typed text The presentation is captured together with an audio stream and can optionally be combined with video The capture application runs on Windows using the Java Runtime Environment the Java Media Framework JMF and the Java Advanced Imaging JAI library Video is encoded with the Indeo Video 5 0 codec The Lecturnity Player for replay of Lecturnity recordings is a Java appli cation A presentation can also be exported to RealMedia or Windows Me dia formats by the Lecturnity Publisher This allows replay in browsers with JavaScript StyleSheets and RealPlayer plug in or Windows Media plug in The Lecturnity editor for optional post processing allows to cut and paste parts of the recording and to combine them with external audio and video streams 1 8 8 Tele TASK t Cube
222. n of the profile data identified by the name entry the thumbnail entry is unused Additional information is stored as key value pairs with the entries These informations are shown in the Properties dialog for the profiles to help the user identifying the profiles While most of this information is stored explicitly or implicitly in the profiles storing them in the XML list makes it available to the setup dialog without having to load the relatively big audio profile data files As a side effect this makes the setup dialog independent from format changes in the profile data files 16See Section 4 6 4 for more on the abstract ChalkletKit class and Chalklet interface 17See part on audio settings in Section 2 4 52 CHAPTER 3 THE E CHALK APPLICATION lt entry gt lt name gt Logicrecognation lt name gt lt url gt file etc logicrecognition jar lt url gt lt thumbnail gt lt thumbnail gt lt property key classname value de echalk logicrecognition LogicAnimationKit gt lt property key minheight value 300 gt lt property key minwidth value 300 gt lt property key param no value 3 gt lt property key param 0 name value feedback gt lt property key param 0 value true gt lt property key param 1 name value ini file gt lt property key param 1 value etc logicrec conf gt lt property key param 2 name value diagram gt lt property key param 2 value false gt lt entry gt
223. nal before it is processed by the codec Having audio technicians and professional grade hardware dealing with these problems is no feasible so lution for our scenarios due to their high costs 5 2 2 Enhancing Recordings The approach taken by E Chalk focuses on the special case of lecture recording The system relies on the lecturer using some kind of directional microphone or a headset Both eliminate the influence of room geometry and of cocktail party noise Hay03 Headsets provide good quality but they may restrict the mobility of the speaker A lecture recording system like E Chalk has the advantage that information 5 2 SMART AUDIO RECORDING 97 Audio Profile Wizard Audio Profile Wizard Measurement Report Noise D Sound card 92 0dB Theoretical Equipment 73 0dB Average DC offset Codec 71 0dB Signalto noise ratio 59 0 dB Summary Sound card quality good Equipment quality good Signal level sufficient Estimated Rate of unintelligible words 1 10333 Automatic gain control possible CPU speed sufficient yes Back Next gt Figure 5 4 A report gives a rough estimation of the quality of the equipment Speech intelligibility is calculated according to IEC 268 about speaker and equipment are accessible in advance Using this fact divides the approach into two parts e An expert system presented via a GUI wizard guides the user through a systematic setup and analyzes the recording equipment and the speaker
224. nce the E Chalk software is a multi platform development in Java the corre sponding guidelines for Java programs Sun99 Sun01 were used Interface Logic The interface must adhere to the logic of the user s view not of the internal workings It has to focus on users and their tasks not on the underlying tech 4The only input elements without associated mnemonic shortcuts are those operated with the Enter or Esc keys typically OK and Cancel buttons Of course access by controlling focus with keyboard tabbing is also supported 5This is listed first among the Eight Golden Rules of Interface Design in Shn98 6For multi platform programs some special considerations have to be taken into account For example the color reduction algorithms for different OS produce different output Graph ics that look good on one platform may be ugly on another Sun99 gives rules for designing graphics like button icons that will appear acceptable on all platforms 30 CHAPTER 2 USER INTERFACE nology For example there is no good reason to require E Chalk users to trigger an explicit save Instead sessions are always stored The language in the interface must use clear wording and avoid tech speak Interface texts should be short and to the point since lengthy explanations are rarely read A common mistake in graphical interfaces is the attempt to compensate for explanations not being read by adding even more text Short e
225. nd a few minutes setting up the classroom With this aim of blending E Chalk into the regular teaching environment the design follows the philosophy of Ubiquitous Computing WGB99 Similar observations hold true for the remote learners Most systems for lecture recording require remote learner to install a special client software often designed as a browser plug in This introduces a psychological barrier for first time users compare for example Nie99 Moreover remote learners often do not have the skills or even the permissions e g on campus computers to install such a client software For example ZS02 reports students having trouble installing the Transparent Teleteaching Tool TTT player even though they only had to install Java JMF Java Media Framework and the TTT application The learners should not be required to install any proprietary viewer software or codec and should not be restricted to a certain operating system Therefore it was decided to realize the replay as a Java Applet running in any Java enabled browser 3 The system is not designed to replace teaching in the classroom The record ings should capture the live experience of the lecture s natural flow as well as having the teaching style formed by interactions with a learning audience The 11For example AOF Lecturnity and Camtasia require proprietary player software Others require to install certain Windows Media codecs or rely on th
226. nd allows them to add private notes 1 8 6 AOF AOF 1 authoring on the fly is a system for both synchronous and asyn chronous delivery of lectures Transmission includes whiteboard activities in most cases annotated slides and audio optionally also video and animation applications AOF lectures are usually given using electronic whiteboards or digitizer tablets For asynchronous delivery the client has to download all the presentation material Streaming is only supported for the synchronous scenario Syn chronous delivery is based on the MBone Eri94 Cla98 technology Originally it directly used vic video conferencing tool vat audio conferencing tool and wb shared whiteboard tool from the MBone tool set for showing PostScript slides These tools allow for paging up and down plus simple drawing function alities The AOFwb BO96 was developed for several Unix platforms to replace wb for more features Its successor mlb media lecture board shown in Figure 1 16 is available for Microsoft Windows and handles drawings as vector graphics 1 8 LECTURE RECORDING 25 It can import PostScript and PDF documents using Ghostscript 28 images GIF JPEG TIFF XBM and MPEG 1 2 streams Audio is transmitted and stored as uncompressed PCM aif The aofRec application is used as a synchronous client For replay of recorded lectures a different client program named aofSync is used see Figure 1 16 For optional post production a
227. nd students The board ensures that information stays available providing context for talk and discussion The learners can see how ideas are developed rather than being overwhelmed with final results they are helped to follow the conceptual pro cess The teacher is slowed down to the speed of his or her handwriting giving the students time to follow the lecturer s train of thought The chalk and talk approach results in a much more flexible teaching style than relying on prepared slides Working on a chalkboard supports cre ative thinking illustration and sharing Board drawings can also be used to draw attention to details using circles arrows underlines checks grouping etc The inherent impreciseness and vagueness of freehand drawings holds extra in formation With these great qualities in teaching it comes as no surprise that the chalkboard is still so popular in teaching in many disciplines especially for subjects where complex reasoning has to be taught as in mathematics and the natural sciences These considerations inspired the development of a system called E Chalk 22 Ideally the lecturers are enabled to teach with the system like with a regular blackboard and produce distance teaching material as a by product During classroom teaching the lecturer works directly on a pen active wall display The system tries to enhance teaching in the classroom by allowing the instructor to integrate multimedia elements At the s
228. near future organic displays are expected to be available for large screens eliminating these drawbacks in display technology 1 3 1 Digital Boards Xerox PARC not only pioneered the GUI with the introduction of the Xerox Star System JRV 89 its former division LiveWorks also produced the first digital whiteboard the LiveBoard EPT 92 The system used a rear projection screen controlled by a built in workstation or PC and a set of tracked pens for different colors The system allowed overlay annotations and had the ability to interoperate seamlessly with remote LiveBoards in other locations The BrightBoard SFR96 and the ZombieBoard Sau98 BBJ 98 are both regular whiteboards with markers where the whiteboard actions are tracked by 14The research version used Solaris workstations The version later sold as a commercial product used PCs running Windows 95 1 4 PEN COMPUTING SOFTWARE 9 a video camera Drawing commands triggered actions by the system like a save of the video scanned board content A number of digital whiteboards use basically the same tracking technology as digitizer tablets The boards mainly differ in being larger than the pads and being mounted upright Examples include products like the Numonics IPM series 69 the Promethean ActivBoard series 77 the GTCO whiteboards 31 the TeamBoard 91 and the Panasonic Panaboard 73 They can track the pen both when it is near the board but not touching it si
229. nerstrukturen Microsoft Internet Explorer zur Verf gung gestellt von FU Berlin aag a Qw 2 A O Aa roms Que O 2 2 0 03 Address hep s Ho Rechnerstrukturen Z Board zweierkomp EChaik Video X 4 y gt te u Y Java Applet Window 4 ruren EIER gt Po sitive Zahlen 24 puiste Java Applet Window Figure 2 1 Replay of the first E Chalk lecture recorded 85 in a browser Applet is started for each recorded data stream board audio and video An other Applet a control panel is provided for VCR navigation through archived lectures see Figure 2 1 All these Applets run in a standard Java enabled browser without requiring the user to download a plug in and this solution is completely platform independent The required bandwidth for the transmission of audio and dynamic board content for the setup with the default audio quality is 64kbps The network traffic generated by the board content is negligible compared to the traffic needed by the audio signal since the board uses a vector format Using a video stream requires a further 64kbps The replay provides the distance learner with a live script where the teacher s side notes are preserved In addition a static copy of the final board image as an Adobe PDF file is included for the students to print 2 2 Usability Considerations Usability considerations played an important role in the design of the E Chalk system Only with
230. ng Board Snapshots A tool for creating static board images from board recordings was developed as a side product from the converter to QuickTime and AVI videos described in Section 6 3 Output formats supported so far are JPEG and PPM The converter is implemented both as a Java command line application and as an E Chalk Launchable The calling syntax for the command line is as follows java echalk tools video Board2Image lt lecture dir gt lt trg gt options w lt n gt h lt n gt jpgl ppm p lt n gt yoff lt n gt yatend t lt ts gt d w lt n gt output width preserves aspect ratio unless h given h lt n gt output height preserves aspect ratio unless w given jpg output as jpeg default ppm output in portable pixmap file format ppm p lt n gt show scrolled to page no lt n gt defaults to 0 yoff lt n gt show for scroll offset lt n gt yatend show for scroll offset used at last event t lt ts gt load only events up to timestamp lt ts gt format lt hh gt lt mm gt lt sec gt with lt hh gt lt mm gt integers lt sec gt float significant up to milliseconds d debug mode 6 5 Audio Format Updater Another tool available both as a command line application and a Progressible component is a converter for updating audio recordings from the WWR2 format to WWR3 It was integrated into the main E Chalk application to make the append mode with the new audio format available
231. ng Company Singapore 1996 BIBLIOGRAPHY 171 BGL96 Bia98 BJJ01 BKTO2 BLFN96 BO96 Bol79 BP94 BPSM 04 Bre77 Bro01 Freimuth Bodendorf Robert Grebner and Christian Langenbach The virtual lecture theatre practice and experience In Pro ceedings of the second Russian German Symposium New Media for Education and Training in Computer Science pages 33 40 Moscow Russia November 1996 Infix Verlag Michael H Bianchi AutoAuditorium A fully automatic multi camera system to televise auditorium presentations In Proceeding of the Joint DARPA NIST Smart Spaces Technology Workshop Gaithersburg MD USA July 1998 NIST Dave Berque David K Johnson and Larry Jovanovich Teach ing theory of computation using pen based computers and an electronic whiteboard In Proceedings of the sixth annual con ference on Innovation and technology in computer science educa tion ITiCSE pages 169 172 Canterbury UK June 2001 ACM press Wayne Burleson Stephen Kelley and Santhosh Thampuran A new course in multimedia systems for non technical majors In ASEE Annual Conference Proceedings Montr al Canada June 2002 American Society for Engineering Education Tim Berners Lee Roy T Fielding and Henrik Frystyk Nielsen RFC 1945 Hypertext Transfer Protocol HTTP 1 0 IETF IESG May 1996 Christian Bacher and Thomas Ottmann Tools and services for authoring on the fly In Proceeding
232. ng a high speed Internet access About a third still used a modem connection see Figure 8 10 This is a good indica tor of the importance of having only low bandwidth requirements imposed by 8 4 STUDIES DURING WINTER TERM 2003 04 157 60 49 6 50 40 30 20 10 ES N in A 0 T T T T clearly less slightly less nochange slightly more dearly more Figure 8 11 Note taking behavior reported by students for E Chalk classes in comparison with regular classes 14 125 12 10 8 6 4 2 0 4 0 4 0 4 0 4 0 4 0 4 0 mea 1 2 3 5 6 10 15 20 30 45 60 80 90 100 120 160 180 300 360 minutes per week Figure 8 12 Time reported to be spent doing revision with E Chalk materials in courses where recordings were published on the Web The 53 2 bar for zero minutes per week has been omitted E Chalk Note that these numbers derive from questioning mainly students of Computer Science Mathematics and Engineering subjects In faculties with the average students being less computer inclined high bandwidth connections can be assumed to be even less common A Windows operating system was used by the overall majority 89 fol lowed by Linux and Mac OS X The dominant Web browser was the MS Internet Explorer 66 with Mozilla Netscape ranking second 21 No correla tion exists between E Chalk usage and bandwidth thus it can be
233. ng designed for mobile use according to a survey this feature did not rank highly among instructors AAS 04 Instead the preferred use was stationary Students contributions to the common display are usually done by the lec turer passing his or her tablet around see AAS 04 but experiments with real time feedback from remote participants as collaborative work in the class room have also been done To this end students connecting via a Tablet PC may send annotated slides to the instructor who can choose to present those slides and annotate them him or herself A AV 03 SAHS04 While the setup in connection with the ConferenceXP application would allow to encode the transmitted session to a huge stream for replay with Windows Media Player the reported use of the Classroom Presenter so far is exclusively in synchronous teaching At sub projects the annotations and slide transitions were stored and a custom replay tool was built albeit exclusively for post analysis purposes The annotation patterns of lecturers were analyzed AHP 04b and the effectiveness of handwriting recognition for this kind of content was studied AHP 04a See Section 6 8 for a short outline of the results 1 8 Lecture Recording AutoAuditorium Bia98 3 from Telcordia Technologies formerly named Bell core is a system for automatic camera control in transmission and storage of classroom presentations AutoAuditorium setup uses three cameras one having a
234. ngs and background For example yellow 11As mentioned above Unisys patented the LZW algorithm However decoding data with LZW was always considered free of charge by Unisys Only software that encoded was subject to patent fees 110 CHAPTER 6 TOOLS CONVERTERS ADD ONS E Figure 6 4 For images with transparency the outline border for the intranspar ent parts is computed Figure 6 5 An erasure stroke crossing a regular stroke interferes with the out line writing has good contrast against a black background but are hard to read against white Also drawings on images may be lost for example if black board drawings on white image parts are used with a black board background Trying to solve this by converting the background color in images is not recommendable as this often destroys the image impression and is difficult to handle properly on colors which are similar but not the same like shades of white In the current version a black outline for all visible board elements is added when the background color is changed to white For line strokes and texts this is realized by drawing these elements slightly fattened and turned to black below the colored elements See Figure 6 3 for an example For images their outline has to be computed as transparency is to be handled see Figure 6 4 for an example A drawback of this method is that erasure marks crossing normal drawings are not handled well as illustrated in Fig
235. nn 1588 ma Heutiik AND Wordkit AND Google C Herink AND fWordket OF Googie C Heuristik AND Wordlet Heurktik Without Consraint Select Lenguags Gamin gt Console Add tha wanda Figure 6 8 The indexing tool as a GUI based application with control output for the developer Figure from The04a Windows XP Tablet PC Edition and Microsoft Windows CE The analyzer works as a post processor for recordings implemented both as Java library and as a stand alone application with a graphic front end The application is shown in Figure 6 8 The recognition process performed rather poorly in distinguishing between drawings and text This part of the segmentation process is handled by the Microsoft Tablet PC SDKs Divider see 63 This caused drawings to be interpreted as text cluttering the good recognition results with random ones Several approaches for a post processing have been tried in the project to remove the bad recognitions from the output Simple heuristics on word structure and dictionary lookups were applied Unfortunately dictionary approaches often remove the most significant of the correctly recognized keywords since more unusual words are more important for indexing purposes See The04b for details Any further development of this tool should improve the Divider s strategy A likely reason for the poor performance of the Divider provided by the SDK is that the development kit currently does not all
236. no default meaning that no audio stream is assumed to exists if the parameter is not set e topleftx and toplefty These are optional entries for explicitly positioning the client board s win dow on the screen by defining the values of the window s top left corner If not given these parameters default to zero e scrollbar This is a flag causing a vertical scrollbar to be added to the board window This provides a standard GUI element for vertical scrolling in addition to the drag feature The scrollbar slider s position and size give a visual feedback of the board area s position in the total board history On the other hand because the scrollbar needs a certain amount of space this can make the vertical space available on the user screen too small for the board If not set this parameter defaults to true In the standard HTML tem plates of the E Chalk system the flag is set to the same value as the scrollbar flag in the server giving the remote user a scrollbar exactly when the lecturer used one 11See Section 4 9 for details on java applet AppletContext 136 CHAPTER 7 CLIENT APPLETS e autostart When this flag is set to false the board client starts in pause mode and waits to be externally triggered via with the Masi unpause method for starting to play If the control panel Applet is used it expects the client Applets to wait to be started and therefore letting the control panel synchronize the start time
237. ns The elements that are painted are represented as instances of the abstract class echalk shared form Form the subclass StrokeForm is used to represent a stroke composed of a sequence of connected line segments a TextForm a typed text an ImageForm an image on the board and an AppletForm an Applet A Form object stores its position on the board and provides a paint method to draw itself and a method to test for an intersection with a given rectangle which is used to determine the visibility of Form objects on the board for the current scroll offset The Forms are stored sequentially in a dynamically growing array in order of creation The board uses double buffering to avoid having to call the paint methods of each visible Form each time a repaint request is issued by the window system for example when a portion of the board becomes visible again after being obscured by another window Whenever a new Form is added to the board content it is painted both to the screen and to the board s offscreen buffer On a repaint the offscreen buffer is simply copied to the screen resulting in a fast and flicker free repaint A complete redraw of the offscreen buffer is only needed when scroll events happen or when a clear all command or an undo is issued see Section 4 5 In this case all Forms have to be checked for their visibility given the current scroll offset and the visible ones have to be painted in the order they were added to the board cont
238. nt end of line markers single newline single line feed or a new line followed by a line feed The board always saves events with Unix style line breaks 86 CHAPTER 4 BOARD SERVER is negligible compared to the one used by the audio transmission As shown in Table 4 2 real lectures need less than 1 kbps in average The peaks are in the range of 3 to 5kbps as standard mouse devices generate between 50 and 125 mouse events per second Up to one line segment event is stored per mouse event Considering the syntax of a line form event described below and assuming x coordinates up to 4095 hexadecimal FFF y offsets with scrolling less than 64 1024 lecture duration of up to 4 5h less than 16 milliseconds and Unix style line breaks single newline character a line form event needs up to 46 bytes 3 Note that for embedded image and Applet resources total bandwidth may peak higher although these data are loaded concurrently to the event stream and thus do not block the board event s loading With the introduction of macros and chalklets the bandwidth may also peak higher if no limit for their line events production rate is introduced For this reason the stroke handling queue currently constraints the chalklet output to a line event rate of 100 Hz roughly the same rate as produced by drawing with a USB mouse For the same reason the event rate for a macro is limited to 100 events per second Another approach to keep the bandwi
239. nt will be linear but then everyday academic teaching by lecture is linear by nature Also the instructor does not have to have intimate knowledge of the production process Normal authoring systems for e learning modules either require the teacher to learn how to operate the authoring software or the authoring process to be handled by a team of at least lIn fact with the popularity of constructivistic teaching even systems offering the replay of plain lecture recordings have claimed to be interactive and constructive just because of the control of the recordings replay The developers of MANIC described in Section 1 6 1 write in SSL 97 To provide for interactivity students are given the opportunity to browse the material at their own pace stopping and starting the audio at will and in SVPMO1 they even claim We have based the overall design of the system in Constructivism We believe that the features of the MANIC system described above audio controls controls to move back and forth between the slides a table of contents and a search engine allow for a greater participation of the students in their learning process 2The instructivistic teaching style embodied by lectures can be clearly considered as the dominant teaching form in the natural sciences and in engineering subjects Even though criticized for its one way communication teaching by lecture nevertheless remained popular because of its efficient way to educate large
240. ntaining client classes See section 3 7 for possibilities to customize these files 18Starting the profile wizard from the setup dialog relies on the wizard implementing the Launchable interface described in Section 3 10 1 3 6 STARTING A LECTURE RECORDING 53 echalk board class echalk board Launcher echalk board class args board overwrite board overwrite fechalk lecture conf echalk audio class de echalk audio EchalkAudio echalk audio class args echalk conf dir streamer conf echalk video class WWV Launcher echalk video class args echalk lecture conf Listing 3 5 Recording components properties in file main conf If the lecture is recorded in append mode and with audio recording data in the old audio format it is transformed into the new format Components for the streams to record board audio and or video are loaded and started dynamically The names and parameters of the components are defined in the startup configuration files as properties see Listing 3 5 The loading process relies on the components implementing the interface Launchable described in Section 3 10 1 Using the interface methods the initialization phase and the execution phase are put into different methods because the time needed for initializing the components may differ considerably For example the time for setting up the board component for append mode depends on the size of the previous recording as the board must load the
241. ntly unless a higher bandwidth is used 6 3 Export to QuickTime and AVI Video A program was developed for converting the board and audio streams into a QuickTime or AVI video using the Java Media Framework for encoding the streams The converter is realized both as a Java command line application and as Progressible to be easily integrated into the E Chalk main system and to be usable from the E Chalk command line console Available codecs depend on which one are installed on the system the program is running on The calling MSee Section 4 3 112 CHAPTER 6 TOOLS CONVERTERS ADD ONS ia KovarianzMatrix avi Windows Media Player File View Play Favorites Go Help 5 Klasse A Entscheidung Figure 6 7 A recording converted to AVI replayed with Windows Media Player with 50 zoom syntax for the converter tool is java echalk tools video Echalk2Video lt options gt lt dir gt lt file gt lt dir gt directory containing the echalk recording to encode lt file gt the video file to write options qtl avil c lt codec gt c lt n gt fps lt n gt w lt n gt h lt n gt v d qt output quicktime default avi output avi c lt codec gt selects codec of given name c lt n gt select codec of index lt n gt in the alphabetical list of codecs available for the selected output format mute ignore audio track from the echalk recording fps lt n gt frame rate for encoded video defaults to 25
242. numbers of students 1 1 THE E LEARNING LANDSCAPE 3 x A very important chart description very Important chin deserpiiin Figure 1 1 Effects of frequency based lossy compression on sharp edges Left image encoded with lossless compression as PNG Right same image com pressed with reduction of higher frequencies JPEG two specialists one who knows how to operate the technology and one who knows the subject and the didactics Still this approach needs extra personnel present during the recording to handle the camera and the audio hardware plus provisions to put the recording online in a digital form Naive recording setup will cause these systems to pro duce poor audio and video recordings from live lectures as their codecs assume a clean signal In practice one needs high quality sound equipment and quali fied technical staff to eliminate audience noise reverberation effects changes in illumination etc Even when tailoring this approach to a light weight creation process Carnegie Mellon s Just In Time Lectures calculated a post processing time of about 30 hours per one hour of lecture not including the time for record ing and preparation For the Microsoft Technical Education Group MSTE costs are reported to amount to more than 500 per talk for their video taped trainings with the expenses primarily being costs for staff to record and put the talks online LRGCO1 Not only that this is still quite expensive but enco
243. o the board The queue processes strokes using a FIFO strategy The line segments a Stroke object is composed of are associated with timestamps If a timestamp is in the future the queue waits for the given time before passing on the line draw event otherwise it is processed immediately If the user is drawing the draw event is delayed until the user finishes his or her stroke Users drawings can also split the synthetic strokes into two parts This is important to keep the complete control of the board to the user Handling the two drawing actions concurrently would not be a suitable alternative as this would destroy the connection of the user strokes for undo redo purposes The RequestStrokeQueue does not send the strokes data at a higher rate than one line segment per ten milliseconds to limit the bandwidth taken up by chalklets As a comparison user drawings with a typical USB mouse generate 125 line segments per second while the chalklets are bound to 100 per second See Section 4 11 1 for a more detailed discussion When the board area is scrolled the position of all active chalklets is checked When the area of a chalklet is no longer completely visible it is deactivated It is unregistered from the StrokeSender its pending strokes in the Request StrokeQueue are removed and the Chalklet instance itself is notified of its deactivation so it can release any resources it still holds method 4 9 MATHEMATICAL HANDWRITING RECOGN
244. oaded and as a final fallback the general resources with unspecified language are used For details see 41 or DC01 26 The directories etc and addons are provided to store user defined additions to the E Chalk system The addons directory is used for all resources to be available via the standard E Chalk class loading mechanism described in Section 3 1 1 All other additions for example local files generated by chalklets should reside in etc 58 CHAPTER 3 THE E CHALK APPLICATION El Echalk DEK Genel H Tahta Q Ses E video O Canl Sunucu amp PDF Oturumun Ba l E Chalk 1 Dizine Aktar elec halklecturesitest_tr Use lv Tahta vi Ses v Video Transmission v Cant letim PDF v PDF dosyas yarat Uzman modu Yaram Cikis iptal Figure 3 3 The setup dialog localized to Turkish To map a key string to its localization the method String Txt get String key is used The method String Txt get String key Object a is pro vided for formatted messages In the localization entry references to the array elements can be used to be replaced by the elements transformed to strings for example in the entry Reading file O0 failed the substring 0 is replaced by the array element at index zero The referencing syntax also allows further formatting specifications like number and date format specifications It is the same as for formatted message output with
245. oard image can be received using low bandwidth connections Bibliography AAS 04 AAV 03 Ab099 ADO1 Ado03 aha93 AHP 04a AHP 04b Richard Anderson Ruth Anderson Beth Simon Steven A Wolf man Tammy VanDeGrift and Ken Yasuhara Experiences with a tablet PC based lecture presentation system in computer science courses In Proceedings of the 35th SIGCSE technical symposium on Computer science education pages 56 60 Norfolk VA USA March 2004 ACM press Richard Anderson Ruth Anderson Tammy VanDeGrift Steven A Wolfman and Ken Yasuhara Promoting interaction in large classes with computer mediated feedback In Proceedings of the Computer Support for Collaborative Learning CSCL 2003 pages 119 123 Bergen Norway June 2003 Gregory D Abowd Classroom 2000 An experiment with the instrumentation of a living educational environment IBM Sys tems Journal Special Issue on Pervasive Computing 38 4 508 530 October 1999 Christine Alvarado and Randall Davis Resolving ambiguities to create a natural computer based sketching environment In Pro ceedings of the International Joint Conference on Artificial Intel ligence IJCAI Seattle WA USA August 2001 Adobe Systems Inc PDF Reference Version 1 5 fourth edition August 2003 aha Software corporation aha Inkwriter Handbook Mountain View CA USA 1993 Richard Anderson Crystal Hoyer Craig Prince Jonathan Su Fred Videon
246. oard features a few GUI elements specifically customized for the E Chalk application For choosing a drawing color a subclass of javax swing Checkbox 4The Java package java swing undo provides an extensive collection of interfaces and classes for undo and redo features Unfortunately the undo redo managing mechanism is not available with Java 1 1 and can therefore not be used in the code shared between the board server and client Another shortcoming is that the implementation does not support infinite undo depth For these reasons the Java undo support is not used by the E Chalk board 4 7 BOARD RESOURCE LOADING 69 Figure 4 4 Custom color and size chooser elements from the board s tool dialog was implemented to allow graphical color labels or an image of an eraser as a label for the eraser tool instead of textual labels Instead of a regular javax swing Slider an equivalent component with a logarithmic scale was used for selecting the size of the drawing tool and the font size for typed text because the exactness of drawing sizes is the more important the smaller the drawing size is See Figure 4 4 for an illustration of the chooser components The implementation of the logarithmic slider relies on Java Swing Components delegating their painting and controls to a ComponentUI class using the model delegate variant of the model view controller MVC architecture The board instantiates a standard Java Slider
247. oard option is to add keyboard typing to the board content When the associated button is pressed one can select the start position for the text input The positioning to be performed is signalled by changing the mouse pointer to a text cursor see Figure 2 11 Text typing is then added to the board until the text input is closed by hitting the Enter key or by adding other contents to the board a drawing an image an Applet a new key typing etc If the text is too long to fit into a single line dynamic line breaking is provided automatically Explicit line breaks can be added by Shift Enter Editing by backspace and delete is supported as well as moving the key cursor in the typed text with the left and right arrow key Text inputs are stored in a text history and the history entries can be accessed by the up and down arrows Keyboard input added to the board content just for writing text are of little value but they can be used as requests to a connected computer algebra system or to CGIs as described below 22The replay of Applets actions poses a number of principal problems For this reason handling Applets in E Chalk remained at a very experimental stage See Section 4 9 for a detailed discussion of the problems 2 4 THE E CHALK SERVER APPLICATION 41 00 07 Apple Demo FAR T Hope tz 777 PET Figure 2 12 Left An Applet added to the board Right Snapshot from a lecture using a plot from a computer algebra system
248. oints stroke width and a color The line segments forming the stroke are drawn as if the pen were a circle with the given width i e round line joints and caps are used A convenient way to draw these lines would be to use an instance of the class java awt Graphics2D for painting and set its drawing shape to circle with the setStroke method Unfor tunately Graphics2D is not available in Java 1 1 Because the code for drawing redraws considerably In Java GUI components that permit embedding of other components are subclasses of java awt Container 4 3 TYPING TEXT 67 ascend line sF 5 ee gt height baseline J a descend line Figure 4 2 Vertical font metrics to consider for laying out text Similarly horizontal advance is composed into left side bearing glyph width and right side bearing lines should be the same on the server and client sides and the because the client side cannot be guaranteed to have the Graphics2D available the drawing must rely on the more basic drawing methods provided by java awt Graphics The board draws a line segment as a rectangle with circles at its ends 4 3 Typing Text An echalk shared form TextForm represents typed text by text color font size and position on the board If it is still active i e is still being changed by user key typing it also displays a cursor in the text The user can add all regular characters to the text as well as use delete backspace left and
249. ological and pulse coded Neural Networks is pre sented in Kru05 The author has developed a board chalklet that allows to define networks by drawings and pen drawing actions for loading parameters of neurons The chalklet can graphically simulate these networks The numerical simulation underlying the chalklet visualization is computed by a server that the chalklet connects to using Java RMI calls See Figure 6 14 for example snapshots 6 12 4 Simulation of Logic Circuits A chalklet has been written for teaching computer architecture principles which is capable of simulating hand drawn logic circuits Liw04 To classify the user input the chalklet uses a multilayer neural network trained with backpropaga tion It recognizes clock elements And Or Not Multiplexer and Demultiplexer gates and connections between the control elements Circuits can also be saved to the local disk for reuse as modules in other logic chalklet instances El ements that are touched by the eraser are completely erased by the chalklet repainting the element using the background color The recognized circuit is simulated by using the Hades framework Hen98 32 Handwritten zeros and ones set the inputs of the circuits for simulation Alternatively the user can choose an animated simulation for all possible inputs optionally combined with a state timing diagram as shown in Figure 6 15 122 CHAPTER 6 TOOLS CONVERTERS ADD ONS Figure 6 15 The logic
250. om Stanford Univer sity to Freie Universitat Berlin by combining E Chalk with a video conferencing solution ae A r Mubble Sort Marr OIL rn 9 25 7 El Boord nubi 3 7 de s a Figure 8 6 The E Chalk client running on a mobile phone display technologies still have to be added to the E Chalk client For example the image could be scaled using a kind of fish eye view and the board could automatically center the current area of changes 8 2 Evaluations Two field studies Sch03 FKR 04b have been conducted on university courses to evaluate the use of E Chalk its impact on teaching and its acceptance under real life conditions These studies were arranged by media psychologists from Freie Universitat FU Berlin and Technische Universitat TU Berlin The emphasis in the examinations lay on the explorative description of key questions such as the acceptance of the software and possible effects on the students motivation for studying The evaluated courses were held at FU and TU Berlin The results are summarized in the following sections 8 3 STUDIES DURING SUMMER TERM 2003 149 questionnaires uni approx start end lecture title versity class size of term of term sum Neural Networks FU 80 36 24 60 Introduction to Numerics TU 40 18 0 18 Calculus II for Engineers TU 300 117 0 117 Linear Algebra for TU 300 94 0 94 Engineers Numerics for Engineers TU 50 50 36 86 Introduction
251. on http www unisys com about__unisys lzw Video4Linux 2 http linux bytesex org v412 Virtual Ink Mimio http www mimio com Wacom Inc http www wacom com Wacom s LCD tablets http www wacom com lcdtablets Waterloo Maple Inc http www maplesoft com Webcast Berkeley http webcast berkeley edu WebEx Training Center http www webex com Wolfram Research Inc http www wolfram com WWR2 World Wide Radio 2 http www javaradio de Zero G InstallAnywhere http www zerog com goto installanywhere 198 WEB REFERENCES 111 Erhard Zorn Lineare Algebra f r Ingenieure Eigenwerte und Eigenvektoren E Chalk recording winter term 2003 04 http www moses tu berlin de Mathematik LineareAlgebra WS_2003_2004 L3 Echalk linazorn_2004 01 27 Appendix Zusammenfassung Diese Arbeit beschreibt eine elektronische Kreidetafel fiir die Lehre Das ent wickelte Softwaresystem kann f r den Pr senzunterricht ebenso wie f r den Fer nunterricht verwendet werden Es erm glicht die Pr senzlehre durch multime diale Elemente zu bereichern ohne dass die intuitive Bedienbarkeit der klas sischen Kreidetafel verloren geht Zugleich wird das Material f r die Fernlehre ohne Mehraufwand produziert quasi als Nebenprodukt des Pr senzunterrich tes Dazu wird die Entwicklung des Tafelbildes und der begleitende Ton des Dozenten aufgezeichnet Die Vorgehenweise vermeidet die blicherweise enor
252. on but PDF users and learners using both types of material expressed a clearly positive judgment see Figure 8 15 8 4 STUDIES DURING WINTER TERM 2003 04 159 clearly rather no change rather clearly hampered hampered easened easened more PDF more replay both evenly none Figure 8 15 Average values and their 95 confidence intervals for opinions on simplification evaluated separately by preferred type of revision material The evaluation also examined the students opinions on the quality of the system The answers on visual impression showed a slight tendency towards a favorable opinion with no significant differences between classroom teaching and replay The acoustic quality of the instructor s talk was judged positively in classroom teaching and got worse ratings for the replay see Figure 8 16 This result was a major motivation to enhance the audio recording quality in E Chalk by the approaches described in Section 5 2 Despite the shortcomings in audio quality the overall quality of the system was clearly seen as positive both in classroom teaching and in replay Using E Chalk in the evaluated course received above average marks from 73 of all students See Figure 8 17 for a detailed breakdown of the proportions To compare E Chalk with other teaching techniques the students were asked to judge in a fictional comparison between E Chalk taught classes and classes using other teaching technologies The comparison w
253. on of the PDF generator and the JMF audio plug in for Exymen Stephan Lehmann implemented the program to convert E Chalk recordings to Windows ASF files Dr Peter R man added capabilities for function definition and function plot ting for the small built in computer algebra system Sebastian Frielitz and Robert Giinzler realized the connection with an Oracle database and Thomas Reimann implemented the tool for automatic upload to a BlackBoard LMS The handwriting synthesis is the work of Yark Schroeder and the PowerPoint importer was done by Shirzad Kamawall and Alexandar Rakovski Florian Theimer has to be credited for the extraction of keywords by means of hand writing recognition on recorded board data The logic recognition chalklet is the work of Marcus Liwicki The TicTacToe chalklet was realized by him too Chalklets described on algorithmic animations are developed by Dr Margarita Esponda Olga Krupina authored the chalklet on Neural Network simulations Henrik Steffien and Brendan O Connor devel oped the Python interpreting chalklet The FU data wall was designed by Prof Dr Raul Rojas The laser pen tracking used by the data wall is founded on the work of Michael Diener The bluetooth extension possibilities were tested by Jorg Rebenstorf Most of the actual work in setting up the data wall is to be credited to Christian Zick He also was of great practical assistance to all project members on numerous occasions 111 Joachim
254. on to index recorded presentations for search and access over the web In Proceedings of the IADIS International Confer ence on WWW Internet ICWI pages 135 143 Lisbon Portu gal November 2002 TADIS Jason I Hong and James A Landay SATIN a toolkit for in formal ink based applications In Proceedings of the thirteenth annual ACM symposium on User interface software and technol ogy UIST pages 63 72 San Diego CA USA November 2000 ACM press Jason I Hong James A Landay Chris Long and Jennifer Mankoff Sketch recognizers from the end user s the designer s and the programmer s perspective In Randall Davis James Lan day and Tom Stahovich editors Papers from 2002 AAAI Spring Symposium Sketch Understanding Workshop number SS 02 08 in Technical Report pages 73 77 AAAI press Stanford CA USA March 2002 Don Hopkins The design and implementation of pie menus Dr Dobb s Journal 16 12 16 26 December 1991 Wolfgang H rst Indexing searching and skimming of multime dia documents containing recorded lectures and live presentations In Proceedings of the eleventh ACM International Conference on Multimedia pages 450 451 Berkeley CA USA November 2003 ACM press Takeo Igarashi W Keith Edwards Anthony LaMarca and Elizabeth D Mynatt An architecture for pen based interaction on electronic whiteboards In Proceedings of the fifth international working conference on Advanced Visual Interfaces
255. onitor shown in Figure 3 5 Another Launchable used only for debugging from the command line console is OscarLaunch It allows to access the Oscar OSGi component management system Launching it adds all commands of the Oscar OSGi shell to the command interpreter allowing to load update and start Oscar bundles from the command line A sub interface of Launchable de echalk util Progressible is provided for implementing processes which can report their progress when launched For example the module converting E Chalk audio data from the old WWR2 for mat to WWR3 is a Progressible The sub interface extents the Launchable by adding a getProgress method which returns the relative progress as a double ranging from zero to one When the setup dialog converts the audio 32For example recording by the audio component needs to be stopped by deorbit 33The default constructor is a constructor with an empty parameter list 34The Oscar OSGi system is used by the audio and video server implementations to manage encoding and streaming components see Sections 5 1 1 and 5 3 35The Oscar shell command are assigned a common prefix in the E Chalk command inter preter This prefix given as an argument to the Launchable serves to avoid name collisions with the interpreter s built in commands 64 CHAPTER 3 THE E CHALK APPLICATION format to WWR3 it can show a progress bar for the conversion to give the user feedback 3 10 2 Message Logging
256. or LightGray Cot setSize 300 200 Die kleinst m gliche Anzahl von Kisten Bins der Gr e 1 mit der alle Objekte verpackt werden k nnen Beispiel 7 Objekte mit Gr en 0 2 0 5 0 4 0 7 0 1 0 3 0 8 Figure 1 16 Tools from the AOF package Left The mlb tool for recording lectures image from 1 Right A recorded lecture replayed by the Java imple mentation of the aofSync player The ZenStarter program is used to start different eClass system components using different options Starting ZenPad triggers the ZenStarters for audio and video encoding After the recording session the Stream Weaver application is used to build HTML documents integrating the timestamped streams Also a list of links to each annotated slide as well as links to the encoded audio and video streams and visited URLs is produced The annotated slides are transformed to GIF and JPEG images Post processing is reported to take about one minute for a complete lecture The generated material is stored in a database The HTML pages generated from slides have a size of about 20 200 kB per lecture the audio stream 3 5 MB and the video 5 7 MB For replay the viewer can browse through the graphic slides and choose the Real stream to jump to the time position of a slide See Figure 1 15 for an example The StuPad TA99 TAB99 students notepad extension of eClass broad casts the instructor s writing to the students desk a
257. ort vectors gives the share of training vectors stored as support vectors in the SVM representation ad EA right subscript below Figure 4 13 Regions thresholds and centroids of different symbol types superscript top left superscript ge A right seve superscript sight below right subscript below subscript Beet Neural Network was trained with the RPROP algorithm applying the standard sigmoid and its standard parameter values RB93 The number of hidden units for each one were the same of the dimension of the feature vector Table 4 1 summarizes the results obtained for each of the classifiers Structural Analysis of Mathematical Expressions Relations in mathematical notation are defined explicitly or implicitly by the position and size of symbols in the expressions Cha70 Depending on a sym bol s meaning it can have relations to symbols in regions classified as top left above superscript right subscript below below left and subexpression Figure 4 13 shows such regions For example the operands of the fraction operator a horizontal bar are the numerator and denominator and are expected to lie in the regions above and bottom respectively Mathematical notation is represented by a recognizer in a data structure similar to the one used in ZBC02 as a hierarchical structure of nested baselines where a baseline is a list of symbols which represent a horizontal arrangement of symbols in the expression Each
258. ote users interactions will usually not fit together with the lecturer s recorded Applet interaction See Section 4 9 1 for a discussion of the Applet replay problems For the Applet class to be loadable on the client side they must located in the board client Applets classpath For replay from a repository this can be done by putting the Applet files into one Jar archive with the code for the E Chalk clients For live transmissions this is not possible because the Jar archive is loaded once when the remote user connects and the Applets to be used in the lecture are not yet stored by the server In this case the codebase parameter should be used to load all the classes both E Chalk client Applets and board integrated Applets from the applet directory Therefore the E Chalk code must then reside there too 7 2 5 Board Parameters There are no mandatory Applet parameters of the board client Applet all are optional The parameters are e port Giving this parameter marks a live transmission The parameter is the decimal port number to connect to on the live server The server must 10For the current implementation of the E Chalk system this is not automatically handled The template handling in Section 3 7 can be easily configured to handle the live case but bundling together the Applet classes in a Jar archive is not yet supported and has to be done manually 7 2 BOARD CLIENT 135 be the Web server the Applet is loaded from
259. ous Computing In fact according to Wei93 the first Ubiquitous Computing tech nology to be deployed was a digital whiteboard the Xerox LiveBoard 1 5 1 Personal Note Taking Storing pen based annotations as personal notes is one of the main applications of PDAs and Tablet PCs coming with pen input software like the aha Inkwriter aha93 and the Windows Journal In contrast to the CSCW tools these types of notes are not primarily meant to be shared with co workers The objective of the Dynomite WSS97a WSS 97b dynamically organized ink and audio notebook is to maintain to do lists personal diaries address lists and other notes It records pen actions audio may be added optionally The handwritten notes are given creation timestamps For retrieval of the notes a keyword query interface was created Filochat WHW94 aims at replacing the traditional dictaphone It uses an LCD tablet for indexing the recorded audio by hand written notes A header with time and date information plus space for a handwritten topic and name is automatically generated for each new notes section The recorded audio can be accessed for replay by a seek option or by selecting the associated note The Audio Notebook Sti96 Sti97 SASO1 is another approach to combine a digital audio recorder and a notebook but it is built as a physical device using real paper for note taking see Figure 1 6 It relies on a digitizing pen for 12 CHAPTER 1 INTRODUCTION AND
260. out that there were many eight or nine points where audio gain could be adjusted This and the fact that the microphones were frequently mispositioned caused many difficulties in establishing sta ble and comfortable audio levels Tsi99 5 2 1 Sources of Interference Unfortunately there are many potential audio distortion sources in lecture halls and classrooms Those with the greatest impact on the recording will be men tioned here For a more detailed discussion of these problems see for exam ple Dic97 Kat02 Any room is filled with multiple sources of noise Students are murmuring doors slam cellular phones ring Reverberation effects depend on the geometry of the room and on the amount of occupied seats Professional speakers are trained to keep their voice up at a constant level but lecturers rarely do so When the audience get less quiet at the end of a lecture teachers unconsciously raise their voice with negative effects to the recording quality if the signal is 96 CHAPTER 5 AUDIO AND VIDEO SERVERS e Audio Profile Wizard Detecting the input line Searching for input devices at sound card SB Audigy 2 ZS Audio FF40 Input line Line In 2 lt Back went gt Figure 5 3 Soundcard ports are scanned for input devices not leveled out Even movements of the lecturer can create noise Coughs and sneezes both of the audience and the speaker result in irritating sounds Additional noise can
261. ow to tag the strokes generated from the board with timestamps 20Strokes fetched from a connection with a mouse driver are generated with time informa tion but there is no method to add them to strokes generated synthetically The SDK allows to associate extra information with its Stroke objects by lookup keys It it possible that a key already exists for timestamps but none is given by the current SDK documentation 6 9 MACRO RECORDER 117 _ Echalk Record Macros Macro Name Macro 1 Save Dir Imacrosimacro001 3 Choose v Add to Bookmarks with Speed Factor b o OK Exit Figure 6 9 The setup dialog of the macro recorder 6 9 Macro Recorder The format for a board macro is the same as for a lecture containing a board stream Only Applet and clear all events are disallowed in board macros Macros are basically a short lecture recording with the board being the sole recorded stream The macro recorder application allows to create a sequence of macros using the current board settings from the main application To enforce compatible assumptions between the macro recording and the board session a macro is only available at the board if they use the same background color and the width is not bigger than the current board width Note that macros recorded with the macro creator are available on recordings with the current board settings When the macro recorder is started it opens the dialog shown in Figur
262. plate for ongoing recording video wwv xml video components graph definition Listing 3 1 Files installed in the configuration directory ard s configuration file path defining it locally to the entry for the configuration directory The character as a literal can be represented in entries by the empty variable For properties with no definitions in the startup configuration file default values are used The settings for a lecture recording which are changed by the setup dia log are stored in a second Properties file referenced by the startup property echalk lecture conf After reading the properties from the main configuration file the applica tion s command line parameters are evaluated in order of appearance Three types of command line parameters are recognized Parameters in the form of X lt key gt lt value gt are used to override setup dialog property entries stored in the settings file This may be used to start E Chalk from a script auto generating the lecture s output directory e g using a combination of user name and date Parameters with the syntax lt key gt lt value gt without a leading X are used to override entries from the startup configuration file Entries with out a character or in the form f lt path gt are interpreted as property file from which startup configuration properties are loaded with the ability to override the entries from the standard startup configuration file See Listing 3 1 fo
263. plet are e slidefile This mandatory parameter gives the relative URL of the slide show com mand file to be used e delayoffset and masiclient These parameters are identical to the board client parameters of the same name used for synchronizing with the audio client see Section 7 2 5 17See RLJ98 for target names Chapter 8 Experiences and Evaluation 8 1 Case Studies Practical experiences with full fledged E Chalk lectures have been gathered at the Computer Science department of Freie Universitat Berlin since the summer term of 2001 At Technische Universitat Berlin eight lecture halls and seminar rooms of the departments of Mathematics and Physics have been equipped with E Chalk since the winter term of 2002 03 In the summer term of 2003 about 1 100 students were taught with E Chalk at these two universities FKR03 and the numbers of students were similar in the following terms About 800 instal lations of E Chalk are in operation around the world as of September 2004 with 80 of them reckoned to be used regularly The majority of E Chalk instal lations is found in university teaching but also in practical training instruction for technicians 55 56 as well as in training scenarios at the Deutsche Bahn German Rail and the Bundeswehr German Army The Berlin Department of Education initiated an evaluation of whiteboards using E Chalk in Berlin elementary and secondary schools Within the CidS Computer in die S
264. plet itself Action events and key events have the form timestamp AppletEvent Action n id actionname mod comp timestamp AppletEvent key n id keycode mod comp 39The pop up triggering mouse event is platform dependent For example on Mac OS X the pop up menus are triggered by the mouse button being pressed down on Windows on the mouse button being released 40To identify the event component the client relies on the subcomponent enumerating methods returning the elements in the same order As the Java API does not specify this order it may differ among different Java environments even though this has not been observed in tests of E Chalk so far 90 CHAPTER 4 BOARD SERVER with n id mod and component sequence given the same as for mouse events The entry actionname is the command string associated with the action event keycode is the integer key code of the key typed pressed or released with the event Text and Text Input The event for creating a new text form takes the following arguments string its initial value x y the inital baseline position for the text c the text color and size the font size The event is defined by timestamp F orm Text string x y c size where the string is MIME encoded to ensure encoding independent representa tion As long as the text is in edit mode it features a text input cursor and accepts editing changes from the user The text creating event positions the cursor at the end
265. ply walk to the chalkboard and start up a spontaneous talk with a high degree of learner interaction A good chalkboard lecture should automatically result in a good e learning lesson The didactic advantages and the easy handling of the tra ditional chalkboard should be preserved while extending its reach to distance learning Storage and transmission of the lecture must be realizable with negli gible additional effort In the classroom the system tries to enhance teaching quality by enabling the instructor to integrate multimedia elements Students should be given the time to grasp the concepts After the course they have access to a recording of the lecture with all relevant information To minimize barriers for first time users they should be able to replay the recordings using just a standard Web browser without requiring them to install any special software Chapter 2 User Interface 2 1 Overview In the Lecture Room The E Chalk system starts with a setup dialog for the recording settings In most cases the instructor just keeps the settings that were stored from the previous session changing just the entries for the lecture title and the path to store the lecture to After hitting the OK button the system s user interface metaphor changes from the computer desktop to the chalkboard a display to be shared with an audience The E Chalk board window occupies the whole screen The instructor draws and writes on the board with a p
266. ported An older version was also localized to Spanish and parts of the E Chalk application have been localized to Turkish See Section 3 9 for a description of the E Chalk internationalization architecture 2 4 The E Chalk Server Application When the main E Chalk application is started a splashscreen window is shown until the E Chalk setup dialog appears Showing this splashscreen gives the user feedback on the applications loading process still running 2 4 THE E CHALK SERVER APPLICATION 33 Eile Edit 7 General Board 9 Audio Even lke server amp por al J E c Ec CHJ Session Title E Chalk 1 ULLLZTTITETTETETTEEETETETEEEETTEERETEEE TEREE TE EEEE a Export Dir ctechalklecturestlecture i Choose IBHREHRRRFRHERRRHRSRRERSRHR FRHRRRRERFRFERFRFERERERRNR Use the echalk board for the session Use lv Board vi Audio Video Allowed vals lt bool gt Default echalk board true Transmission _ Transmit Live lechalk board true PDF A Create PDF File Board window width iS Allowed vals lt pos int gt Default values is screen width oard width 1024 Create an Adobe Acrobat PDF From Board Content aire Board window height Allowed vals lt pos int gt Expert Mode Default value is screen height Site oard height 768 Initial position of the board window Allowed vals lt unsigned gt Default board topleft x 0 oard topleft x 0
267. ported Any a other than FF intransparent is currently ignored Each of the following lines contains an event given in the order of creation time An event line is separated into tokens by the character The first token is always the timestamp of the event given in milliseconds relative to the lecture s start time It is saved in hexadecimal formar like all numerical values in the event file if not stated otherwise 38 After the timestamp tokens specify the type of event followed by tokens for the event specific parameters Any extra trailing tokens are ignored In the following events these optional entries are only given for the NOP operation where they are used for commentaries see Section 6 6 which then would have to be able to parse files in an erroneous format 37Transparency for images is supported but the color values of images are not saved directly in the events file see below on image events 38 Any usage of decimal numbers is due to historical reasons Examples are the numbers for image and Applet resource file and the decimal encoding for board width and height entries in the header 88 CHAPTER 4 BOARD SERVER eci 680 420 Example Lecture 000000 O Nop created 03 10 28 14 50 36 GMT 01 ed3 Form Line 48 2a 48 59 Ff f00f 00 3 efe Form Line 48 59 47 65 f f 0Of f00 3 31e9Form Line 218 117 218 118 ff00ff00 3 4d2e8 Nop end 03 10 28 14 50 52 GMT 01 4d2e8 Nop append 03 10 28 15 05 13 GMT 01 5325
268. programming This will have to be examined in detail Changing the uncompressed ASCII board event format to a binary format with differential encoding would allow to relax the limits of maximum event rates on chalklets and macros without running the risk of exceeding bandwidth limitations see Section 4 10 1 Functional chalklets may even be created so as to encompass existing drawings on the board and then perform particular actions on these drawings or even on the output of previously executed chalklets To assist in chalklets development the supporting API should be extended Methods are to be provided to conveniently create Stroke objects for basic geometric shapes boxes circles etc and for printing texts perhaps even in a handwritten style Ideally a recognition engine for strokes should become part of the API to support complex interpretations of stroke input to chalklets Geometric inter pretation of freehand sketching is already an active research area often in the context of pen active whiteboards with office type applications For example the SATIN HL00 Java toolkit is a framework for pen based applications which processes both stroke objects and stroke gestures Example applications built on top of SATIN are DENIM LNHLO0 for building Web pages by sketching SketchySPICE HLOO as a simple circuit CAD tool and SILK HLLMO2 for prototyping user interfaces by sketching 2This feature was suggested by Wat04
269. pt to pre load the slides into the browser cache to reduce delays in slide transitions All slides have to be converted manually by the author to a browser supported image format 1 6 3 AudioGraph AudioGraph JSS98 Jes00 Jes01 Jes03 2 is an authoring system combining images lecturer annotations highlighting of selected areas and playback of sound clips The author sequentially adds elements like hand drawn images or imported images to a slide and determines the transition times between the elements meaning that the elements appear one after another He can also add audio to be played the length of the audio chunks usually determining the transition times between graphical elements The system generates one 18 CHAPTER 1 INTRODUCTION AND RELATED WORK 2 White Board Player Hep Que MEN Osean Hrs Que O gt Address El Hp lowes surrey aru TeactinglCeurses DCNotors trans hem Transformers basic equations Figure 1 11 An AudioGraph lecture on transformers 61 replaying a handwrit ten slide HTML page per slide and the user can navigate between the slides Within one slide the user can start the slide animation from the beginning as well as pause and resume the animation A progress bar shows the position within the slide animation but random access is not supported AudioGraph is designed for low bandwidth requirements The audio stream is encoded using GSM 6 1 mobile telecommunication compression
270. quired to select the line manually With a single source plugged in this occurs only with digital input lines because they produce no background noise At this stage several hardware errors can also be detected for example if noise is constantly at zero decibel there must be a short circuit 98 CHAPTER 5 AUDIO AND VIDEO SERVERS Audiograbber Doene en H Equalizer Coes Mixer Monitor Figure 5 5 The chain of the audio signal during recording Mixer con The audio system analyzer takes control over the sound card mixer There is no need for the user to deal with the operating system s mixer The next step is to record the sound card background noise The user is asked to remove any input device from the sound card A few seconds of noise are recorded The signal is analyzed to detect possible hardware problems or handling errors For example overflows or critical noise levels result in descrip tive warnings After recording sound card noise level the user is asked to replug and switch on the sound equipment Again several seconds of silence are recorded and analyzed Comparing this signal to the previous recording exposes several han dling and hardware errors For example a recording device plugged into the wrong input line is easily detected After having recorded background noise the user is asked to record phrases with special properties The phrase choice is language dependent A phrase con
271. r Algebra Systems The list of computer algebra system available in the setup is defined by the configuration entry echalk computingserver add It is a comma separated list of de echalk util EvaluatorKit classes These classes provide static builder methods that returns a de echalk util Evaluator instance to serve as The format is given in the API documentation of the load and store methods of Properties see 40 10See Section 2 4 11See part on board settings in Section 2 4 3 3 CONNECTING COMPUTER ALGEBRA SYSTEMS 49 Initial Values Chalk Size SS Echalk Maple Properties hb Setup for integrating Maple of Maple Inc Note that a local Maple installation is needed for this KernelPath Transparency Kernel Parameters Use transparent backgrounds in grafics vi Transparency ox came Handwriting Recognition for 7 Scrollbar Cancel Heip Figure 3 1 Setup dialog generated for a computing server setup info with three parameters showing the tabbed panel of the boolean parameter Transparency actual connection to a computer algebra system like Mathematica Other static methods return a localized name and an optional icon for the EvaluatorKit as well as a de echalk util KitSetupInfo which describes the parameters needed by the builder method and an overall localized description of the kit For each of these parameters a KitSetupInfo ParamInfo object is given by
272. r bringing the cursor to the beginning of the text with the home key or to the end with the end key the event timestamp Text Cursor idz allows to move the cursor to an arbitrary character index idz 4 12 Live Server The board s live server thread listens at the TCP server socket for incoming con nections When a client connects a connection thread is spawned for the client and the offset to the board s initial time index the offset to event timestamp 0 is sent as hexadecimal ASCII followed by a newline This enables the client board Applet to synchronize its timing with the server board timestamps Then the current content of the event file is flushed over the socket connection The connection is maintained until the server or the client terminates Whenever a new event is created on the board is it sent over to all open client connections For a description of the client side see Section 7 2 When the board session ends it sends clients a single terminate event see Section 4 11 2 92 CHAPTER 4 BOARD SERVER Chapter 5 Audio and Video Servers 5 1 The WWR Audio Server The audio subsystem used for E Chalk is a pure Java successor of the World Wide Radio WWR system FL98 109 initially named WWR2 Man99 with the change to a new audio format renamed WWR3 The system is a TCP IP based audio streaming system that uses lossy compression to achieve interruption free transmission over small bandwidth Internet connection
273. r control by pen input they suffer from occlusion by the writing hand T Cube VN94 is a system to type input in the absence of a keyboard i e with a mouse or a pen using pie menus predicting this being faster than linear menus or software keyboards according to Fitts Law Fit54 Quickwriting Per98 also uses circular menus but tries to reach interruption free input sequences by returning to the home position between keys instead of signalling each key input by lifting the pen Cirrin MA98 is a key input software originally designed for users with repetitive strain injury Like Quickwriting it allows to enter the keys without having to lift the pen before a word ends quickly training the user to remember the key input motions as kind of gestures Its main difference to Quickwriting 17The input system called T Cube is not related to the distance teaching system t Cube from Universitat Trier described in Section 1 8 8 18Fitts Law states that the time to acquire a target is proportional to log d s with d the distance of movement from start to target center and s is the size of the target 1 5 PEN BASED OFFICE AND CSCW TOOLS 11 is that it arranges the letters in a circle giving a rather fine graded wheel of choices instead of a hierarchical organization see Figure 1 5 For standard commands instead of key inputs the flowmenus described in Section 1 5 6 also use the homing strategy to allow for rapid input of conse
274. r example echalk conf dir audiowizard conf the default entry for the audio wiz l Java Properties objects are hash tables which map String keys to String entries Referenced properties may include the startup configuration properties as well as some special E Chalk properties made available at runtime 45 46 CHAPTER 3 THE E CHALK APPLICATION main conf E Chalk s startup configuration echalk conf lecture settings prefs conf user s preferences on suppressing warnings streamer conf configuration for audio video streaming console rc console startup command file console dat console command history file echalk log session log file error messages etc streamer log log file for audio video streamer system audio audiowizard conf configuration for audio profile wizard audio converter conf configuration of audio format converter audio profiles xml audio profile list audio wwr3 xml audio components graph definition board texthistory dat board text history file bookmarks applets xml bookmarks of Applets bookmarks cgis xml bookmarks of CGI calls bookmarks chalklets xml bookmarks of chalklets bookmarks images xml bookmarks of images bookmarks macros xml bookmarks of board macros profiles data directory containing audio profiles templates templates conf HTML template handler setup file templates archived def localized template for replay templates live def localized template for live transmission templates recording def localized tem
275. r the list of E Chalk configuration files 3Because all of E Chalk s configuration properties start with a lowercase letter and not with a dash there is no problem in distinguishing the two parameter types 3 2 DATA MODEL OF THE SETTINGS 47 3 1 1 Dynamically Loaded Classes Several components of the system are realized as dynamically loaded classes The boards connection to computer algebra system and the handwriting recog nition system belong to these as well as a number of components implementing the interface de echalk util Launchable The Launchables include the au dio video and board subsystems as well as the PDF converter and some debug ging tools The classes to be loaded are defined as properties in the configuration files The system delegates the class loading to the class de echalk util Re sources Its loading mechanism does not only search the classes from the Java VM s classpath but from classes stored in the directory lt echalk install dir gt addons either residing directly in it or stored in a Jar archive file This allows developers of E Chalk components to quickly test their components by adding them to the addons directory without the need to compile the classes into the E Chalk system core libraries or to change the classpath 3 1 2 Multiuser Configuration In the standard setup all configuration files of E Chalk reside in the lt echalk install dir gt conf directory The startup configuration file
276. rations on the recording see Figure 7 3 Timed slide shows can also be combined with lecture recordings see Section 6 13 Displaying them is handled by the slide show Applet For live transmission the client Applets read the lecture data through a socket connection from the E Chalk server program Because Java Applets can only connect to the server their class code is loaded from the E Chalk server must run on the Web server or the Web server must act as proxy for E Chalk s server sockets For an overview to the client server connections for live transmittions see Figure 7 1 When the lecture is replayed from archive all data are loaded using the Web server s HTTP service As described below the board video and slideshower Applets can synchronize their replay with the Audio stream The reason for adapting everything according to the audio stream is that interruptions in the audio stream are perceived as quite disturbing compared to stalls in the video or board replay See Figure 7 2 for an overview While the standard setup is to access a lecture with a Java enabled browser or with the Java appletviewer by an HTTP address the client Applets can also be run from the local file system for both live and archived lectures Of course for the live session the E Chalk server must then be running on the same server as the client 1An early implementation of E Chalk also allowed a live connected shifted in time for late connects When re
277. recordings and successfully took an exam for the lecture Not only university students use the materials The E Chalk team have also got reports from high school students using the opportunity to take a look at university lectures with the help of E Chalk 8 1 3 Replay on Hand held Devices The replay of E Chalk recordings is also possible on hand held devices Although a Java Runtime Environment is often not pre installed Java 1 1 can be set up on PDAs by installing the Jeode Java Virtual Machine for Microsoft Pocket PC from Esmertec 24 This is sufficient to run the E Chalk replay The same holds true for those mobile phones running Windows CE Pocket PC see Figure 8 6 Other Java capable mobiles for example those that run Symbian OS normally support only the Java 2 Micro Edition J2ME Running E Chalk on such devices would require a reimplementation of the client as Java Midlet The main problem with running E Chalk on a mobile or a pocket PC is the small display Lectures recorded with a resolution used by standard PC displays will be hard to follow on a hand held device requiring the user to scroll a lot to the actual center of activity For use with small screens smart 3This can be easily done by editing the E Chalk HTML templates see Section 3 7 148 CHAPTER 8 EXPERIENCES AND EVALUATION Figure 8 5 Left Using a microphone and a digitizer tablet lessons can be cre ated at home Right A lecture on robotics transmitted fr
278. regular use of the E Chalk system the demand arose for a tool to restore damaged recordings At Technische Universitat Berlin several recordings were damaged due to a faulty memory chip in the machine running the E Chalk server The recorded data were corrupted by bit flips and sometimes even the OS crashed The recording was then shut down without properly closing the output files so that nonsense data were appended A command line tool was developed for checking the integrity of audio and board data and restoring them by replacing damaged audio packets with si lence and dropping invalid board events The tool can handle both E Chalk audio formats WWR2 and WWR3 Checking and repairing video is not yet supported usage gt echalk tools checker Main lt options gt lt lecture gt options o lt outdir gt nal va nb o lt outdir gt write fixed lecture to the given directory na do not check repair audio data va output verbose audio packet info nb do not check repair board data Replacing the damaged audio packets with silent packets prevents board and audio from becoming unsynchronized unless the audio data is so badly damaged that the number of packets cannot be identified anymore In this case synchronization must be adjusted manually using the Exymen editor see Section 6 13 A possible extension would be a capability to repair board events where the redundancy of the event representation allows reconstruction 6
279. resource is loaded as raw byte data it is transformed to data the board can handle Text data is decoded according to its character encoding For text plain MIME type the character is directly passed directly to the board For text html the text is parsed and converted to plain text by the echalk board util HtmlDoc class The transformation is similar to the for matting done by a text only browser like Lynx 57 though only a subset of HTML is currently supported See Figure 4 10 for an example An alternative would be to convert the HTML to an image by using the HTML rendering capabilities of Java The drawbacks are that using images would need more bandwidth for the transmission that the Java HTML inter pretation often fails due to non standard HTML data that its implementation is very heavy weight and perceivably slow Images are decoded to an java awt Image object by using the standard Java image creation methods Before the image is given to the board the raw image data are saved in the image resource directory in order to make the image accessible to any E Chalk clients An Applet resource is given by an HTML page where the Applet is em bedded and its parameters are defined The resource s bytes are decoded by transforming them into HTML text taking the character encoding into account and parsing all lt applet gt blocks with the corresponding parameters using the class echalk shared applet HtmlAppletBlock After storing the HTM
280. ress Thomas P Moran Patrick Chiu William van Melle and Gordon Kurtenbach Implicit structure for pen based systems within a freeform interaction paradigm In Proceedings of the conference on Human factors in computing systems CHI pages 487 494 Denver CO USA May 1995 ACM press Michael B Monagan Keith O Geddes K M Heal G Labaln and Stefan M Vorkoetter Maple V Programming Guide Release 5 May 1997 Scott Minneman Steve Harrison Bill Janssen Gordon Kurten bach Thomas Moran lan Smith and Bill van Melle A confeder ation of tools for capturing and accessing collaborative activity In Proceedings of the third ACM international conference on Multi media pages 523 534 San Francisco CA USA November 1995 ACM press Elizabeth D Mynatt Take Igarashi W Keith Edwards and An thony LaMarca Flatland New dimensions in office whiteboards In Proceedings of the conference on Human Factors in Computing Systems CHI pages 346 353 Pittsburgh PA USA May 1999 ACM press Elizabeth D Mynatt Take Igarashi W Keith Edwards and An thony LaMarca Designing an augmented writing surface IEEE Computer Graphics and Applications 20 4 55 61 July 2000 David Mioduser and Ralf Nachmias WWW in education In Heimo H Adelsberger Betty Collis and Jan M Pawlowski ed itors Handbook on Information Technologies for Education amp Training chapter 2 pages 23 43 Springer Verlag Heidelberg Germany 2002
281. right text arrows to move the cursor in the text and the home and end keys to jump to the start or the end of the text Also paste from clipboard with Ctr1 V and emacs style cut to clipboard kill from cursor to end of line with Ctr1 K are supported as well as a text history accessible with the up and down keys The history is kept between session The number of entries in the history is determined by a property in the echalk conf file Key inputs that are duplicates to their predecessor are omitted from the history A TextForm splits the typed text in rows with dynamically created line breaks to avoid the text running out of the board area see Figure 4 1 The vertical metrics of a font needed for the layout are illustrated in Figure 4 2 When painting a call to the java awt Graphics method drawString is done for each row because drawString does not handle newlines itself 4 4 Images and Applets An echalk shared form ImageForm contains the board position of the repre sented image and the image data as java awt Image Is paints itself by using the java awt Graphics method drawImage An echalk shared form AppletForm instance encapsulate an Applet as an java applet Applet and its position on the board as rectangle The painting 3Because the basic circle drawing with Graphics results in drawings with displeasing asym metries for even circle diameters due to a Java bug see IDs 4080106 4151279 4151636 and related in the Java bug database
282. roperties file format 4Described in Section 4 6 2 5Described in Section 4 8 6The Launchable interface id described in Section 3 10 1 Loading the Java resources like images for image buttons is also handled by this class SIt can be redefined either by editing the conf main conf file or using command line ar guments as described in Section 3 1 48 CHAPTER 3 THE E CHALK APPLICATION All GUI elements of the startup dialog that accept user input are registered in the dialog s Settings object The associated Property key as well as a mapping between localized GUI values and their internal Property values may be accessed via the Settings object It also allows to change a registered input component s state by setting its corresponding Property value via its key This mechanism is used to change settings by commands using the command line console see Section 3 10 1 Structure Preserving Property Parsing A Java Properties file can contain both key value pairs and comments They are processed line by line while lines end at the end of the file or with one of the line terminators n r or n r Comments are lines that start with one of the characters or Except for empty lines all lines are interpreted as key value pairs Key and value are separated by a whitespace a or a If these characters appear in the key they must be escaped by a Whitespaces directly after the separator are also ignored if the entry starts
283. rt A Streitz Peter Tandler Christian M ller Tomfelde and Shin ichi Konomi Roomware Towards the next generation of human computer interaction based on an integrated design of real BIBLIOGRAPHY 187 Sun99 Sun01 SVPMO1 TA99 TAB99 Tap04 Tes81 The04a The04b TRO2 TRO3 and virtual worlds In John M Carroll editor Human Computer Interaction in the New Millenium ACM press chapter 25 pages 553 578 Addison Wesley August 2001 Sun Microsystems Inc Java Look and Feel Design Guidelines Java Series Addison Wesley June 1999 Sun Microsystems Inc Java Look and Feel Design Guidelines Advanced Topics Java Series Addison Wesley December 2001 Agustin Schapira Kimberly De Vries and Cris Pedregal Martin MANIC An open source system to create and deliver courses over the internet In Proceedings of the 2001 Symposium On Applica tions and the Internet pages 21 26 San Diego CA USA Jan uary 2001 IEEE Computer Society Press Khai N Truong and Gregory D Abowd StuPad Integrating student notes with class lectures In Proceedings of the Conference on Human Factors in Computing Systems CHI volume 2 pages 208 209 Pittsburgh PA USA May 1999 ACM press Khai N Truong Gregory D Abowd and Jason A Brotherton Personalizing the capture of public experiences In Proceedings of the twelfth annual ACM symposium on User interface software and technology UIST pages 121 13
284. rved Concurrently arm Orientation 8 Portrait Landscape Board 9996 Audio 9998 7 Background vi Force White Create Color PDF Grayscale PDF Both Figure 2 8 Left The live server setup page The video server port element is disabled because video recording is disabled in the general settings Right The tabbed page on PDF generation El Echalk Recording 4 Audio recording is running Figure 2 9 Information dialog during recording when only the audio stream is stored 2 4 2 The Board Component Tool Dialog and Basic Drawing When the board component is started the user can use the pen device for painting Color and drawing thickness are controlled with a tool dialog see Figure 2 10 One can also change from the standard drawing tool the chalk to the eraser tool It draws with the background color and has the drawing width defined independently from the chalk tool as a bigger stroke is usually wanted for the eraser The sliders to control the sizes of the drawing tools and any typed text use a logarithmic scale since fine size control is much more important for the smaller sizes The mouse pointer on the board is shown as a circle of the current drawing erasing size or as symbolic chalk eraser icon when they become too big see Figure 2 11 The tool dialog includes buttons to cause undo or redo actions on the board contents The undo stack is not boun
285. s ink features to Office applications In 1 7 PRESENTATION AND CLASSROOM ENHANCEMENT 19 Linked List Nodes are a Fit struct which we ll use to ref le si 4 gt fiola le 0a Ai aol dE ela al gt Linked List Nodes Je Bo Ase Linked List Nodes of Draw the picture them 15 op a next WLL top item 15 op gt next WLL Figure 1 12 Classroom Presenter Left View of the instructor s screen Middle View projected for the audience Right View for remote students All three images from 13 An early system to integrate prepared slides handwriting of the instructor and student contributions submitted from their desks is the Lecturer s Assistant BP94 The Pebbles MSG98 Mye00 Mye01 project uses PDAs for controlling pre sentations including stylus based drawing ActiveClass RSTG03 uses PDAs to promote interaction by allowing stu dents to submit text based questions to the instructor and to respond to polls submitted by the instructor 1 7 1 BIRD Note taking System The BIRD beacon identified realtime display Note taking System 30 is an application based on NET that allows the lecturer to use annotated slides The students use laptops with wireless access to the same subnet as the instructor uses and use a client software installed on their machines to receive the lecture data That software also allows
286. s In order to guarantee continuous playing sound data have to be buffered creating a small delay between recording and playback see Section 7 3 5 1 1 Server Architecture The WWR3 streaming server is modeled as a flow graph see Figure 5 1 for an example The graph consists of five basic types of nodes Sources Targets Forks Mixers and Pipes Technically any component that wants to live inside the graph becomes a node by inheriting one of these five superclasses The graph that connects these components to a directed graph is specified by an XML file Nodes are described via general properties for example to make the system select a certain audio codec that compresses down to a certain band width The system then searches for an appropriate codec first locally and then in the Internet The structure of the graph can be changed and the nodes can be updated while the system is running All data are synchronized automatically This allows clients to trigger the server to be updated on the fly to match their requirements instead of forcing the client to load an updated module For example nodes exists for both WWR and Windows Media Player The system can be configured to load the appropriate modules when a client connects with either Windows Media Player or with the Java based client for a live connection The nodes of the flow graph are realized as components of the SOPA self organizing processing and streaming architecture framework
287. s a non directory file not ending with aslash see above The parameter must also be set in live streaming mode i e when the parameter archivemode is undefined if WWR3 data are streamed 15For live transmissions this problem does not occur since the replay time is determined by the receiving time 140 CHAPTER 7 CLIENT APPLETS World Wide Video Mi E3 Achtung Applet Fenster Figure 7 7 A video of the instructor replayed in the video client Applet e server This parameter is identical in function to the board Applet parameter of the same name It is used for debugging purposes only e errorurl and endurl The parameter errorurl defines a URL to redirect the browser to if the connection is down or too slow In Internet radio this was used to either redirect to an alternative broadcaster or to change to an HTML page with the audio client for a connection serving at a lower bandwidth The latter approach allows to have a set of streams with different bandwidth where the client automatically selects the highest bandwidth the listener s connection can handle The parameter endurl was also only used for Internet radio If set to a URL the browser changes to the given location when the client terminates on reaching the end of the stream 7 4 Video Client As stated in Section 5 3 in the description of the video format the E Chalk video is intended more to add a personal touch to recorded lectures than to be a major so
288. s evaluated in the study described in Section 8 4 2 120 CHAPTER 6 TOOLS CONVERTERS ADD ONS Figure 6 13 Chalklet for animated algorithms in mid operation Left Sorting handdrawn lines according to their height with Bubble Sort Right Finding the shortest path in a weighted graph with Dijkstra s algorithm Figures from Esp04 6 12 Example Chalklets 6 12 1 EchoChalklet and TicTacToe Two chalklets that were not developed for use in actual lecturing are nonethe less included to serve as examples for developers using the E Chalk API to create their own chalklets Their source code is linked in the documentation of E Chalk s Java API classes The EchoChalklet just reflects any Stroke it receives at a center line in its input area with a certain delay to the input The delay and whether the reflection is to be done horizontally or vertically are parameters for the chalklet s bookmark setup The TicTacToe chalklet allows to play a game of Tic Tac Toe against a computer opponent see Figure 6 12 The computer does not play an optimal strategy it only pre computes the results for one move of the opponent giving human players a chance to win The chalklet does not take any parameters Which player gets the first move is determined at random As long as the match has not reached a decision undos are handled by the chalklet Marks to positions already set or marks that can be attributed to more than one position are considered invalid
289. s of the Conference on Ed ucational Multimedia and Hypermedia ED Media pages 7 12 Boston MA USA June 1996 Steven F Boll Supression of acoustic noise in speech by spectral substraction IEEE Transactions on Acoustics Speech and Signal Processing 28 2 113 120 April 1979 Chris Buckalew and Alan Porter The lecturer s assistant In Proceedings of the twenty fifth technical symposium on Computer science education SIGCSE volume 26 1 of SIGCSE Bulletin pages 193 197 Phoenix AR USA March 1994 ACM press Tim Bray Jean Paoli C Michael Sperberg McQueen Eve Maler and Francois Yergeau Extensible Markup Language XML 1 0 W3C Recommendation third edition February 2004 Jack Bresenham A linear algorithm for incremental digital dis play of circular arcs Communications of the ACM 20 100 106 February 1977 Jason A Brotherton Enriching Everyday Experiences through the Automated Capture and Access of Live Experiences eClass Building Observing and Understanding the Impact of Capture and Access in an Educational Domain PhD thesis Georgia Tech College of Computer December 2001 172 Byr00 Cha70 CKRWO99 Cla98 Cla99 CMMS03 Com82 Com87 Com90 Cre97 CS91 CY00 DC97 BIBLIOGRAPHY Deborah Byrne Make text more readable for older people The Backgrounder Oregon State University Extension and Experiment Station Communications pages 1 2 November Decemb
290. s the browser to load URLs at given timestamps The data for the slide show are a text file containing one entry per line irrespective of the platform specific encoding standard different line separators may adhere to A command to display a document is showurl urluhhummusslutarget where url is the URL of the document to be displayed and hh mm ss are the display time as hour minute and second offset to replay start time given as two digit decimals The optional field target specifies the frame to open the document in either the name of the frame in the HTML or one of the symbolic targets 16The java applet AppletContext method showDocument URL String is used to show the pages According to the Java API documentation browsers are free to ignore the calls see Java API 42 In practice however all Java capable browsers can be assumed to support this method As a side note these document to be shown need not be stored locally in contrast to the images and Applets loaded by the board client As the slide show documents are loaded into the browser and not into the Applet the usual Applet security restrictions do not apply to these resources 142 CHAPTER 7 CLIENT APPLETS 3 C Chotk Lecture Hogar Microsoft Internet Explorer zur Verf gung gestellt von FU Derlin Die engtischo Kunstdos 18 ha Einf hrung Lektion Test Lileratur Glossar Sitemap Linke Teit 1 William Hogarth L Audio Texitassung Zusatzmateria
291. se button appear ance for both play and pause modes are defined It may also contain an image for filling the slider track See Figure 7 4 for example skin graphics e autoplay This is an optional flag to determine if the Masi instances should start immediately by the control panel when their initialization phase is finished Otherwise the control panel will set the replay to pause mode at start and it must be started manually by the user The parameter defaults to true In fact this is not possible with streaming formats 132 CHAPTER 7 CLIENT APPLETS 2 Console Rechnerstrukturen a Ex Java Applet Window Figure 7 3 A snapshot of the client control panel frame with mouse over effect for the play pause button e xandy These are optional x and y coordinates as decimal integer for the top left position of the control panels frame By default the position will be determined by the users window manager 7 2 Board Client 7 2 1 Event Handling As described in Chapter 4 the board client uses the same classes as the board server component just without the authoring elements It uses the DrawPanel component to interpret the events In addition to several classes the board client shares with the server side board the client board uses four classes First the Applet class echalk client Client which is the main class of the client It inherits from Masi see above realizing the interfaces for control by the control panel
292. se driver during drawing actions Because mouse drivers often deliver points faster than users change drawing directions omitting the redundant points results in a considerable data reduction In prac tice the stroke points are reduced by a factor of two or three For obvious reasons it is not possible to directly include an interactive Ap plet into the PDF Instead they are represented as an image with an Applet symbol In the second phase page breaks are determined and in the final phase the actual PDF representation is constructed and written An early implementation lLaunchable and its sub interface Progressible are described in Section 3 10 1 See Section 4 6 4 for implementation details of Chalklets and associated classes 3In fact the PDF converter looks for a saved snapshot image of the Applet to include When no such snapshot is found it uses a standard Applet icon to mark the Applet s place However the implementation of the server side board does not store such snapshots yet 105 106 CHAPTER 6 TOOLS CONVERTERS ADD ONS knipping localhost gt java echalk tools pdf Board2PDF usage gt java echalk tools pdf Board2PDF lt key gt lt val gt lt lecture dir gt Recognized standart keys and their values pdf conf lt filename gt pdf media a 0 6 letter halfletter legallnote ledger 11 17 pdf portrait truelfalse pdf bw true false pdf bg2white true false pdf outlines truelfalse pdf outfile lt fi
293. since Java s security model does not allow unsigned Applets to connect to other servers If Web server and E Chalk server are not running on the same machine the Web server must be running a proxy to forward the E Chalk live streams between E Chalk server and E Chalk client Applet Otherwise live transmission is not possible Of course this restriction also holds for live transmissions without the board stream for example if only the audio signal is streamed The port parameter has no default value meaning that replay from archive is assumed as a default If the parameter is set but a parse error occurs or if the port number is out of the valid range the parameter is set to 9996 the server s default port number e delayoffset This parameter is used to give a delay in milliseconds for displaying live events it is ignored if the board does not run in live mode The delay is introduced to compensate for the delay the audio client needs for buffering The default value is 12 700 ms which is the live delay used by the old WWR2 implementation of the audio client See Section 7 3 for details e masiclient The Applet name given to a Masi instance to synchronize with usually the audio client Applet If a name is given and if the board client can find a Masi extending Applet with the given name in its AppletContext it starts a thread that ensures synchronization with the named Applet as described in Section 7 2 1 The parameter has
294. so the results on speech intelligibility from the second comparative study in Section 8 4 1 where detrimental effects were observed 160 CHAPTER 8 EXPERIENCES AND EVALUATION visual quality acoustic quality 50 50 45 classroom H 45 classroom H 40 Drepla 40 Dreplay 35 35 30 30 u F 25 i F 25 20 j 20 1 5 B u im im Im I al o yerybad ratherkad medium rather good very good verybad ratherkad medium rather good very good Figure 8 16 Opinions on visual left and acoustic right quality both in class room and replay Replay quality was only evaluated in those courses where the associated streams were published on the Web overall quality usage in course 507 163 50 435 467 aa mclassroom H 45 x Dreplay 2 305 ES 26 8 30 22 21 225 20 198 20 131 12 2 E 155 EAI 65 7400 10 4 4 4 5 8 5 E 5 o L 0 m very bad rather bad medium rather good very good verybad rather bad medium rather good very good Figure 8 17 Left Answers on the overall quality of the system Right Ratings for using E Chalk in the evaluated course As to the disadvantages a low readability of the instructors handwriting was by far the most common complaint made 121 times followed by criticizing the vis
295. something may be wrong When an operation takes some time some sort of feedback should be given Tolerances are reported to lie in the range of one to three seconds with most guidelines working with one second Joh00 Sun01 Shi00 For prolonged operation in E Chalk a feedback dialog is displayed after half a second If the progress of the operation can be measured a progress bar is shown Ideally the process can be canceled allowing to discontinue operations taking too much time The perceived performance of responsive operations is much better than that of non responsive ones even when the latter are technically a bit faster 2 3 Installing E Chalk To provide for easy installation of the E Chalk software an installer for each supported platform Windows Linux and experimentally also OS X has been provided InstallAnywhere 110 is used to build installers for these platforms setting up the complete E Chalk software package with all resource and con figuration file This includes the installation of a Java Runtime Environment enabling the software to rely on a specific Java version to be installed On Linux systems the package is registered to the RPM database on Windows and OS X the components are registered in the platform application menu see Figure 2 2 The installer supports several different languages localizing both the instal lation process and the installed E Chalk application Currently only English and German are sup
296. t and the users is done via another Web interface This is not the only repository support tested with E Chalk In the con text of a lecture given in the winter term of 2003 04 where E Chalk and a Learning Management System LMS were employed a GUI application was created for storing into the LMS namely BlackBoard 4 Version 6 However the implementation of the tool remained at a very experimental stage 6 11 Handwriting Synthesis Another application that started as a student project converts ASCII text to handwritten text on the E Chalk board The output features script style con nections between different characters of a word and strokes are timed Figure 6 11 shows an example of the output The handwriting synthesis application was written as a command line tool that generates an E Chalk lecture usable as a board macro Another application provides a graphical interface to define character shapes and the types of connection with neighboring characters The application can be thought of as an inverse handwriting recognition software generating human like output from machine input A later version might be used in future E Chalk implementations to replace all remaining ASCII output on the board like the text output of computing algebra servers or from CGI queries In addition a converter for text to board strokes should be added to the E Chalk API for the benefit of chalklet developers The lecture is the course on Neural Network
297. taining many plosives is used to determine the range of gain This mea surement of the signal dynamics is used to adjust the automatic gain control By adjusting sound card mixer input gain at the current port the gain control levels out the signal The average signal level should be maximized but over flows must be avoided If too many overflows are detected or if the average signal is too low the user is given a choice of possible improvements During the frequency test a sentence containing several sibilants is recorded to figure out the upper bound frequency The system looks at the frequency spectrum to warn the user about equipment anomalies The final recording serves as the basis for a simulation The user is asked to record a typical start of a lecture The recording is filtered compressed and uncompressed again Users can listen to their voice exactly as it will sound in the recording If necessary an equalizer allows experienced users to further fine tune the frequency spectrum manually The time for filtering and compressing is measured If this process takes too long it is very likely that audio packets are lost during real recording due to a slow computer At the end of the simulation process a report will be displayed as shown in Figure 5 4 The report summarizes the most important measurements and grades sound card equipment and signal quality into the categories excellent good sufficient scant and inapplicable
298. teboards Like Tivoli it is a collaborative application for informal office work Its design is based on a two button event model a standard pen down on the board surface is translated into a stroke pressing an extra button triggers a pie menu for controlling the application The input space is organized into pages using a flip chart metaphor Sessions are stored automatically IMEL99 The basic primitives of the board content are pen strokes which are au tomatically grouped together based on spatial proximity into segments by using their bounding boxes IELM00 The board elements can be dragged around or automatically reordered It features automatic shrinking of segments when squeezed to screen border screen real estate management and a lay out control to prevent overlapping Segments can be applied behaviors to be triggered by the context menu for example modifying to a map like output replacing single strokes by double line streets adding check boxes to lines of written text straightening line segments of sketches or a calculator behavior processing inputs of numbers and basic calculations New behaviors can be plugged into the system MIELOO See Figure 1 8 for examples on behaviors Flatland also has a powerful multi undo mechanism that allows rollback in time Each of the segments has an individual time line stored with a special transaction model allowing undos and redos based on the segment s history
299. ters for example to adjust the gain of an audio chunk Plug ins can provide a MediaEditor to record new data A MediaEditor also acts as a replay tool Optionally it may allow editing actions in the space coordinates see for example Figure 6 20 6 13 3 Editable Formats Exymen is distributed 26 including a number of standard plug ins for the following formats e E Chalk board format described in Section 4 10 e E Chalk audio format both the old WWR2 and the new WWR3 audio described in Section 5 1 e E Chalk video format described in Section 5 3 e E Chalk slide show format described in Section 7 5 26The ISO based their file format specification for MPEG 4 on QuickTime too PEO2 126 CHAPTER 6 TOOLS CONVERTERS ADD ONS Figure 6 19 Editing an E Chalk lecture combing a slide show and audio e E Chalk lecture recordings handled by a meta plug in using all four plug ins listed above e JMF supported audio formats 44 including MP3 QuickTime audio and PCM audio data wav aiff snd au etc e C64 SID audio Com82 Yan83 This was integrated mainly for educa tional purposes on historical computer architecture The fact that the C64 SID format is a fully computationally complete program format made the editing support of this format quite challenging JFK03 FJK04a The audio plug ins allow to convert a stream of any of its supported for
300. text of small screens in Section 8 1 3 6The Numonics IPM whiteboard used in the lectures at TU locates the pen by electromag netic induction with wires embedded in the board at a density of 300 per inch In practice the accuracy is not limited by the hardware but by the calibration of the mapping between phys ical location and projection image and estimation errors introduced by the driver software doing this mapping 152 CHAPTER 8 EXPERIENCES AND EVALUATION 40 Intensity not at all 30 E sometimes O intensive 20 4 10 um Figure 8 8 Exam results in correlation with the usage of E Chalk materials where 1 0 is the best grade Another frequent complaint was the bad handwriting of the instructor 40 times and the missing audio in the TU Berlin recordings 20 times Low handwriting quality is likely to be due to the low resolution mentioned above Suggestions for improvements included among others the application of integrated handwriting recognition an additional projection of the former board content similar to the approach taken with the FU data wall see Section 8 1 1 a pointer or marker tool discussed as a future addition in Section 9 and displaying the current time The latter feature was added to the system shortly after the study by showing the recorded time duration or the local time in the title of the board frame Which of the two options is used can be configured
301. the Java URLConnection mechanism Instead the more efficient standard file read is used An early implementation which relied on the standard URL mechanism suffered from a noticeable slowdown due to overhead introduced by the Java URLConnection mechanism Java also allows access to URLs which need authentication The programmer has to set a java net Authentificator to use the mechanism The E Chalk board defines the echalk board util LoginAuthentificator as such an au thenticator When a user tries to access a protected URL resource an authen tication dialog is displayed The dialog shows all the information available for the request the authentication message from the remote side and the address of the protected resource and allows it to input the user s password without the password to be shown see Figure 4 7 On a failed authentication the dialog reopens until the user successfully authenticates or chooses to cancel An au thentication for a resource is only needed once per session since authentication data are cached by E Chalk for the next request The standard URL handling of Java supports authentication only for HTTP requests However Java allows to replace the handling mechanism of URLs on a protocol basis and to define handlers for new protocols by a call to the java net URL method setURLStreamHandlerFactory In the E Chalk system the FTP protocol handling was extended to support authentication The HTTP protocol handlin
302. the mechanisms for strokes being passed from the server side board to chalklets and vice versa In contrast to images and Applets the server does not have to mirror the chalklet because the client does not have to load the chalklet itself It only receives the strokes produced by the chalklet and saved as board events 18See Section 3 4 for setting chalklet parameters 4 8 STROKE DELIVERY 77 4 7 5 Resource Handling The echalk board rc TextHandler pastes the text to handle directly a text row below the request that produced the text The echalk board rc ImageHandler lets the user place the image resource to the board as described in Section 2 4 Applet resources are placed similar by the echalk board rc AppletHandler see Section 4 10 for the details of Applets instantiation The echalk board rc ChalkletHandler lets the user select the chalklet s area and marks it by drawing the area s border Once the area is determined the de echalk util ChalkletContext for the new Chalklet can be constructed and the ChalkletFactory is used to build a new Chalklet instance The new object is registered to the echalk board rc StrokeSender queue which handles the forwarding of user stroke events to the stroke listeners see Section 4 8 1 After that the board returns to the default user paint mode The echalk board rc MacroHandler lets the user select where the macro should start and then starts to play the macro on the board in an extra thr
303. them to save snapshots of the received screen content 1 7 2 ConferenceXP Presenter Classroom Presenter The ConferenceXP Presenter or Classroom Presenter AAS 04 13 is used for both classroom teaching and synchronous distance teaching and was first deployed in summer 2002 The Presenter is designed to run on Windows Tablet PCs In lectures it organizes content in pages slides are shown by the lecturer and can be annotated To provide a kind of whiteboard functionality the instructor may insert empty slides to be filled with freehand writing and drawings For distance teaching the system is used by a video conference in connection with ConferenceXP 16 The transmission is two way and a client needs to have Classroom Presenter ConferenceXP and PowerPoint XP or 2000 installed The data transfer is built on top of multicast communication which does not guarantee delivery The developers report difficulties to transmit large objects such as slides especially in a wireless environment 13 As a workaround the application allows a manual re broadcast to be triggered by the client Office 2008 these are already integrated 20 CHAPTER 1 INTRODUCTION AND RELATED WORK The system produces three different views the instructor s desk including special controls the image sent to the projector in classroom teaching maximiz ing the current slide with its annotations and a third view for remote access see Figure 1 12 While bei
304. thorization Needed Please enter authorization for protected area at http page mi fu berlin de 80 Username Iknipping Password enteras Cancel Figure 4 7 Authentication dialog shown for loading password protected re sources error The java net HttpURLConnection has a method getResponseCode which would allow the URLLoad to return the HTTP request s response code to examine failed loadings in more detail for example to distinguish between a document not found a forbidden access a timeout or a user canceled autho rization Unfortunately this method does not always return the response code when the document was not successfully loaded It often throws an exception due to a Java bug The HTTP handling mechanism used in E Chalk fixes this problem For HTTP requests the MIME type is accessible via the URLConnection as HTTP Server sent this information with their reply for HTTP versions since 1 0 BLFN96 For other protocols this information is guessed from the extension of the URL s file part or if an extension is not given from the data content using the magic number entry for file types 4 7 2 Requests to Computer Algebra Systems Another type of resource access are requests to computer algebra systems E Chalk s API provides interfaces to develop connectors for arbitrary system The connectors for Mathematica and Maple are already provided as well as the connector to a simple built in
305. tic HTML pages with the grabbed snapshots of the notes Selection of an image starts the video playback beginning at the snapshots time offset 24 Dynomite is described in Section 1 5 1 1 8 LECTURE RECORDING 23 E Earliest UI interaction paradigms 2 Examples l MS DOS shell UNIX shell dBase I GPSS Command Languages a Figure 1 15 A replay of an eClass lecture with slides and audio 1 8 4 DEBBIE DyKnow With the DEBBIE BJJ01 BBW04 DePauw electronic blackboard for in teractive education system and its commercial offspring DyKnow 20 dy namic knowledge transfer students are equipped with PCs with video tablets Tablet PCs or PCs with digitizer tablets with built in LCD screens The in structor uses an electronic whiteboard or also a video tablet The system allows to present prepared material keyboard typing and freehand sketches The material is transmitted over a network connection to all student workstations Students can add their own annotations both freehand and typed The stu dents may send portions of their work space to the teacher who can integrate them in his or her presentation for the entire class to see At the end of the class students can save their workspace for static viewing printing and replay Audio capture is not supported The DyKnow Implementation is based on Microsoft NET Framework and runs under Windows 2000 and XP 1 8 5 Classroom 2000
306. time for installations and updates is low since plug ins tend to be small Even including an HTML based online help none of the plug ins described in Section 6 13 3 is bigger than 200kB The approach of Exymen is inspired Emacs philosophy of free extensibility of the program formulated by Richard Stallman Sta81 It motivated the choice of the acronym for EXtend Your Media Editor Now as the editor s name 6 13 2 Data Structures Media data in Exymen are organized in a hierarchical way similar to Apple s QuickTime App01b format which also serves as a wrapper for different media types 2 The top level data structure is the Program which would correspond to a film reel of the analogous video cutting domain A Program contains a number of MediaTracks A MediaTrack is composed of a sequence of Chunks corresponding to a tape snippet in video cutting ordered along the timeline without overlaps within the track An Exymen plug in fills the chunks with its data It may use an arbitrary representation and has to implement a small number of basic operations on the data e g splitting merging and cloning With these operations video cutting operations along the time scale in Exymen become possible A plug in also has to provide a graphical visualization along the time scale See Figure 6 18 for an example Optionally a plug in may provide media chunk scaling in both time and space and define arbitrary effects on its chunks called fil
307. tion has the disadvantage that the lecturer may cast a shadow on the board inter fering with his or her writing on the board Rear projection systems do not know this problem and they are less susceptible to adverse light conditions but they are also less portable than whiteboards and much more expensive For both systems the display area is large enough for a seminar room of typical size but not for a large auditorium This can be solved by a second LCD projection at a bigger scale The Technische Universitat Berlin applies such a setup regularly see Figure 8 2 An alternative setup is to use a digitizer tablet or a Tablet PC as the input device and combine this with a projection for the audience Digitizing tablets are comparatively cheap and easy to transport Using a model with an integrated display the teacher does not have to turn away from the audience for writing For a fixed installation the tablet can also be integrated into a lectern see Figure 8 3 for an example Digitizing tablets without integrated displays are available for less than 50 8 1 CASE STUDIES 145 E Chalk Figure 8 2 Left E Chalk running on a digital whiteboard with front projection Numonics IPM Right Mathematics lecture at Technische Universitat Berlin using the same digital whiteboard model and an additional projection for the audience Providing the writing surface this way can also be helpful in other scenarios A handicapped professor of
308. tions are found 50 CHAPTER 3 THE E CHALK APPLICATION lt DOCTYPE E Chalk bookmarks lt ELEMENT E Chalk bookmarks entry gt lt ATTLIST E Chalk bookmarks title CDATA REQUIRED gt lt ELEMENT entry name url thumbnail arg property gt lt ELEMENT name PCDATA gt lt ELEMENT url PCDATA gt lt ELEMENT thumbnail ziprgb href gt lt ELEMENT ziprgb PCDATA gt lt ATTLIST ziprgb width CDATA 16 gt lt ATTLIST ziprgb height CDATA 16 gt E I I E I E E 23 z lt ELEMENT href PCDATA gt lt ATTLIST href width CDATA 16 gt lt ATTLIST href height CDATA 16 gt lt ELEMENT arg prompt id gt lt ATTLIST arg post yes no yes gt lt ELEMENT prompt PCDATA gt lt ELEMENT id PCDATA gt lt ELEMENT property EMPTY gt lt ATTLIST property key CDATA REQUIRED gt lt ATTLIST property value CDATA REQUIRED gt 1 gt Listing 3 2 DTD of bookmark files and the audio profile list 3 4 Bookmark Files All bookmarks are stored in XML files with the inline DTD shown in Listing 3 2 Each entry has an name to identify it and a URL to load the data from As an optional field an icon entry named thumbnail is provided for visual identification in the dialogs An icon is stored as a URL reference to an installed image resource or as raw image data A reference is used for an icon image supplied with the E Chalk system accessible in the bookmarks editors with th
309. to the board s current foreground color This allows for adjustments of returned images for the board s colors The Evaluator for Wolfram Mathematica uses a Java connection package provided by Wolfram called JLink 46 E Chalk s implementation allows to connect to a locally installed Mathematica Kernel and can handle both textual answers and graphical plots As default plotting options the plot color is set to the board s current foreground color and the plots background color is set to transparent When Mathematica is connected it is also used to evaluate the requests from E Chalk s mathematical handwriting recognition see Section 4 9 The EvaluatorKit for Maple was integrated due to user requests Like the Mathematica connection the Maple integration can handle both text output and graphical plots It directly starts Maple as a process and realizes the data exchange as reading and writing text data via the process s standard IO streams and plots data via temporary files Maple does not support transparent back ground in plots but E Chalk s MapleKit optionally allows transparency This is realized by parsing the plot s GIF image data and setting its background color to transparent Also any color that is equal to or very near to the board s background color is set to black on light backgrounds or white on dark back grounds so that they remain visible See Figure 4 8 for an example This color modification is not possible
310. to the standard hardly outweighs the risk of losing recordings of complete lectures just because instructors forgetting to save them 2 2 USABILITY CONSIDERATIONS 31 error prone For example the Caps Lock key introduces a mode for typing actions The situation is especially grave when a user is interrupted in his or her action between triggering a mode change and employing it An infamous example of a mode heavy interface is the Unix vi editor To get rid of modes was strongly voiced by Tes81 An example of a com puter system that tried to avoid modes in the user interface was the Canon Cat Ras00 When modes are encountered in a group situation on the elec tronic board they can be expected to be especially disruptive The instructor is not only occupied with the board task he or she also has to keep the audience in mind and any mode error distracts the lecturer and the audience from the content of the lecture While temporal modes should be avoided where possible it will not be pos sible to eliminate them fully When allowing the user to draw with different colors in a painting application or on the E Chalk board having the current color as a mode is necessary Often the interface can help to avoid mode errors by giving visual feedback like the mouse cursor This feedback can go unnoticed as the task and not the feedback is in the locus of the user s attention Ras00 Feedback works best when it is observed as part of the task i
311. tself For example in a painting program the size and shape of the drawing tools can often be chosen Setting the mouse pointer to the outline of the selected tool can protect from a wrong shape or size setting in drawings as the user focuses on the position of the very pointer shape when he or she starts a drawing action According to experiments visual feedbacks can help but kinesthetic ones are much more effective both in preventing errors and in terms of reducing cognitive load SKB92 Important for the effectiveness is the kinesthetic continuity by having the user maintain the mode actively Re active feedback like having to hold down a button performs much better than pro active feedback like having to push a button before the action Temporal modes are also introduced by modal dialogs They were first intro duced by Apple with the Mac OS App87 Their purpose is to get the attention of the user by preventing them from interacting with the main application Un fortunately this means modal dialogs are highly disruptive Dialogs change the locus of attention and often hide information on the screen that is needed by the user for the interaction Modal dialogs are sometimes acceptable to guide users in tasks they triggered themselves The most disruptive usage of modal dialogs is to display messages e g error messages This should be employed very sparingly especially when used to get user input Frequent use of confir m
312. turally performed with a keyboard The board is meant as an interface for a pen device instead of a keyboard Still most non painting board actions can be controlled via the keyboard for example Ctr1 Z is mapped to Undo In the case of having no mouse or pen device to operate the board it is important that the standard shortcut for exiting the application Alt F4 works on the board This can be crucial if one starts E Chalk without a pointing device or if a battery powered input device runs out of power The keyboard shortcuts are also useful to control the board with configurable hardware devices Several digitizer tablets and digital whiteboards allow to map key strokes to special regions of the input area With the board receiving these keystrokes and mapping them to board actions these serve as buttons for board control This interfacing technique is also used for the bluetooth hardware extension of the pen described in Section 8 1 1 Consistency Consistency is an important aspect in user interface design This avoids confu sion in users and helps them to learn to use the interface quickly What is also de sirable is consistency with other applications the interface should adhere to ac cepted standards Standard GUI elements and symbols as well as standard label names should be used wherever they are appropriate Various platforms provide guidelines for adhering the the platform s standards App92 App01a 29 49 68 Si
313. typical messages produced by the client control panel and the three E Chalk clients board audio and video The boolean parameter debug activates additional messages for debugging purposes similar to the server debugging mode described in Section 3 10 2 The parameter s default value is false 12The parameter was introduced for use on those Windows systems that do not recognize the loop back address 127 0 0 1 Note that Windows systems of the 2000 XP family can handle it 138 CHAPTER 7 CLIENT APPLETS 7 3 Audio Client The audio client Applet can play both the older WWR2 and the new WWR3 audio format described in Section 5 1 A WWR2 input stream is decoded with E Chalk s ADPCM to an 8 bit 8 kHz u law mono audio stream which can directly be played by the Java audio system irrespective of the underlying Java version With a WWR3 stream the data decodes to a 16 bit 16 kHz linear mono audio stream This can also be played directly within the browser provided is supports Java 1 3 or later If only Java 1 2 or earlier is supported the client converts the data to 8 bit 8 kHz p law to replay them This means that users with a more recent Java version can listen to the audio at a higher quality than others The recording data and the client used are the same for both types of users To compensate for network jitter the audio client uses a buffer Filling the buffer with data introduces a delay for live transmissions For two way trans
314. ual qualities of the board image 24 times for example demanding a higher screen resolution problems already discussed in the findings part of Section 8 3 However the complaints about handwriting readability increased a lot Presumably this is caused by the change of pen input hardware at Technische Universit t Berlin While the accuracy of the LCD tablets seems to be high enough for the resolution it is supposed harder to produce clear handwriting on a small screen than on the whiteboard where bigger movements are used Some students remarked the board drawings to be not clearly laid out 15 times This is likely to be caused by both the resolution problem and the smaller size of the digitizers and rear projectors compared to a traditional chalkboard The problem of visible board space itself was also criticized 9 times This is a problem not to be solved easily with off the shelf display technology as the aspect ratio of the projection is determined by the computer screen ratio and the height of the board is limited by the instructor s ability to reach the upper part of the board With special hardware setups one can provide more display space in the classroom as shown in Section 8 1 1 For remote access by standard PCs this introduces the need of mechanisms to fit more board content onto a small screen compare Section 8 1 3 Other remarks given at least five times are no recording of audio at TU mentioned 11 times and the lecturin
315. uch more predetermined and less spontaneous To use the words of a university lecturer PowerPoint sucks the life out of a class And04 Some lecture recording tools record work by recording the computer desk top see Section 1 8 1 While technically this allows an instructor greater free dom and encompasses the recording of slide shows it is an unsuitable approach for teaching The desktop metaphor is tailored for personal work as a virtual extension of the physical desktop meant to be used with a mouse and a key board by a single person and not to be shared with an audience The desktop metaphor needs sustained attention to be operated due to the prevalence of modes Disruption of the users workflow is common for example by requiring complex interactions with dialogs The universality of the desktop paradigm turns into a drawback in the lecturing situation As a teacher giving a lecture one is already quite busy with getting the content across even without hav ing to deal with desktop dialogs like creating folders or killing the MS Office Assistant that are a source of distraction for both lecturer and students 4See for example iLectures 36 5See for example the Cornell and the BMRC Lecture Browser 5 described in Section 1 6 2 6 Again most of these systems have the encoding problem mentioned above as almost all use standard video compression codecs See Section 2 2 for a short discussion of modes in user int
316. umane Interface New Directions for Designing Interactive Systems Addison Wesley Boston MA USA 2000 Martin Riedmiller and Heinrich Braun A direct adaptive method for faster backpropagation learning The RPROP algorithm In Proceedings of the IEEE International Conference on Neu ral Networks ICNN pages 586 591 San Francisco CA USA March April 1993 J rg Rebenstorf Entwicklung eines Bluetooth Stifts f r E Kreise FU Bluetooth Pen Diploma s thesis Fachbereich Mathematik und Informatik Freie Universitat Berlin May 2004 Jun Rekimoto A multiple device approach for supporting whiteboard based interactions In Clare Marie Karat Arnold Lund Jo lle Coutaz and John Karat editors Proceedings of the Conference on Human Factors in Computing Systems CHI pages 344 351 Los Angeles CA USA April 1998 ACM press Jiirgen Richter Gebert and Ulrich Kortenkamp The Interactive Geometry Software Cinderella Springer Verlag Heidelberg Ger many July 1999 Ra l Rojas Lars Knipping Gerald Friedland and Bernhard Fr tschl Ende der Kreidezeit Die Zukunft des Mathematikun terrichts DMV Mitteilungen 2 32 37 February 2001 Ra l Rojas Lars Knipping Wolf Ulrich Raffel and Gerald Fried land Elektronische Kreide Eine Java Multimedia Tafel fiir den Prasenz und Fernunterricht Technical Report B 00 17 Fachbere ich Mathematik und Informatik Freie Universitat Berlin October 2000 Ra l Rojas Lars Knipp
317. ung per Kamera an einer Riick projektionswand Ein Lichtgriffel fiir E Chalk Bachelor s thesis Fachbereich Mathematik und Informatik Freie Universitat Berlin 2003 Richard C Davis James A Landay Victor Chen Jonathan Huang Rebecca B Lee Frances C Li James Lin Charles B Morrey III Ben Schleimer Morgan N Price and Bill N Schilit NotePals lightweight note sharing by the group for the group In Proceedings of the Conference on Human Factors in Computing Systems CHI pages 338 345 Pittsburgh PA USA May 1999 ACM Press Anind K Dey Daniel Salber and Gregory D Abowd A concep tual framework and a toolkit for supporting the rapid prototyp ing of context aware applications Human Computer Interaction Journal 16 2 4 97 166 2001 Anchor article of special issue on context aware computing Andreas Eckert Werner Geyer and Wolfgang Effelsberg A dis tance learning system for higher education based on telecommu nications and multimedia In Proceedings of World Conference on Educational Multimedia and Hypermedia ED MEDIA Calgary Canada June 1997 W Keith Edwards Takeo Igarashi Anthony LaMarca and Eliza beth D Mynatt A temporal model for multi level undo and redo In Proceedings of the thirteenth annual ACM symposium on User interface software and technology UIST pages 31 40 San Diego CA USA November 2000 ACM press Scott Elrod Ken Pier John Tang Brent Welch Richard Bruce Rich Gold D
318. urce of information As high resolution video consumes lots of bandwidth the videos recorded with E Chalk are normally of low resolution See Figure 7 7 for an example The buffering strategy of the video client the differs from the one in the audio client as many client systems may not have enough memory available for buffer ing video for several seconds For video a dynamic cache is implemented that increases and decreases with the amount of memory available Fortunately dis continuous image streams are not as disturbing as discontinuous audio streams Jumping forward and backwards in recorded video is by now handled as in the WWR2 audio The faster approach of VCR operations in WWR3 audio using the index file to jump to the proper offset in the video data file is planned as a future enhancement Since video encoding uses only difference frames except for the very first frame jumping in time generates artifacts in areas which changed only in the skipped time This can be avoided by storing full frames I Frames every few seconds in separate files another feature planned for the recent future In combination with the index file this allows the client 7 5 SLIDE SHOW 141 fast random access and to fully construct the video by loading the most recent I Frame While the storage of the I frames would increase the size of the stored video notably only a single I frame per jump has to be loaded keeping the low bandwidth requirements for th
319. ure 5 2 The steps of the audio profile wizard Ea practice the required bandwidth is much lower as the cleaner signal compresses significantly better see part on filtering techniques in Section 5 2 4 5 2 Smart Audio Recording As described in Section 8 4 2 the audio quality in replay was the most important weakness of the E Chalk system according to user evaluations This caused the change from WWR2 to WWR 3 format but a much greater impact can be achieved by ensuring the quality of the recorded signal before encoding Although often advertised most current audio recording systems cannot yield professional quality recordings just by plugging a microphone into a sound card and starting the lecture Good quality recordings require full time techni cians to set up and monitor the signals or expensive professional grade equip ment or both The idea was to replace the technicians and the specialized hardware by self controlling software components as far as possible FKT04 It is important that the system relieve the user of the technical setup details Currently the audio technology is not easily usable for a layperson generally the networking and video setup was fairly simple but audio setup and operation was cumbersome We had continual prob lems with audio levels microphone placement mixer setups feedback etc Following the audio path from a microphone to remote speaker it turns
320. ure 6 5 Unfortunately there is no way to handle this without the converter computing the rendered page Because the PDF version is often printed in black and white the PDF con verter supports creation of grayscale PDFs Here outlining board elements is not necessary Instead all visible line drawings and text elements are created in black Images are converted to grayscale A possible improvement would be to use grayscale colors for the drawings with gray values corresponding to the contrast of the original color to the background 6 2 Export for Replay in Windows Media Player To allow recorded lectures to be displayed in the Windows Media Player a Windows command line converter to ASF was implemented in Visual C The E Chalk audio data is encoded as WMA Windows Media Audio in the ASF 12This is the default behavior now when the background color is changed The old method is still available through the E Chalk settings or from the converter s command line parameters Background color conversion can also be suppressed See Listing 6 1 13 ASF is the acronym for Advanced Streaming Format later renamed in Advanced Systems Format from the Windows Media framework It is a general wrapper format for multimedia data allowing arbitrary codecs to be used for its contents 6 3 EXPORT TO QUICKTIME AND AVI VIDEO 111 Figure 6 6 A recording converted to ASF replayed with Windows Media Player using a DirectShow plug in file The
321. urrent recognizer engine uses a two step strategy similar to well known approaches BG96 LW97 CY00 The first step is the classifica tion of the stroke data now relying on Support Vector Machines SVMs TRO2 whose non linear classifications Vap98 yield superior classifications for the in creased number of symbol classes The classification now also handled symbols composed of three strokes The second step is to apply a structural analysis technique to obtain a hierarchical structure of the expression which describes 80 CHAPTER 4 BOARD SERVER the mathematical relationships among the symbols A detailed description of the on line mathematical handwriting recognizer can be found in Tap04 Data Preprocessing Strokes delivered by the E Chalk board are considered part of the same sym bol if their distance considering the strokes brush radius is below a certain threshold The online data is then preprocessed TR03 FKST04 in a stan dard way for handwriting recognizer First the direction of the stroke data is normalized A fixed number of points is then taken from the stroke s list of support points the points are smoothed by averaging the coordinates with those of their neighbors The points are then resampled equidistantly the sequence of points pi Pn is replaced by a sequence of points q1 qn having the same distances between successors on the polygonal chain formed by p1 Pn Finally the stroke data are sc
322. using teaching content Production Costs Unfortunately creating e learning material is a laborious process Production costs are reckoned to be in the range of 50 to 200 man hours for one hour of learning content CMMS03 reports on the development of static or dynamic HTML pages On the average one can calculate one person working for a half to up to a full year for the preparation of electronic learning content for only one course 2 CHAPTER 1 INTRODUCTION AND RELATED WORK While the costs of any software and hardware equipment amortize rapidly if enough material is produced the huge costs in personnel make it economically not viable unless the content is either aimed at a very large audience or can be reused many times For the teaching at universities the situation is particularly grave as the contents taught tend to change very fast A cause for this tremendous effort is that traditional teaching know how does not easily match with contemporary authoring tools Apart from technical ef fort it requires a huge amount of work to structure didactic content for the Web even if presented only linearly As a side note the e learning community often argues for producing highly interactive material supporting constructivistic style learning following the learning theory rooted in the works of Jean Piaget and Lev Vygotsky According to constructivism knowledge cannot be simply trans mitted Instead the learners have to actively constru
323. ution would be to integrate a general handwriting recognition feature However reaching a satisfying level of recognition reliability is difficult unless the user is required to learn a special alphabet like Unistroke Integrating a software keyboard is not an adequate option since operation on an E Chalk board is still too awkward Instead using hierarchical pie menus may be a more viable option See Section 1 4 for a description of employing pie menus for key input Transmitting the Board Pointer A feature sometimes requested by instructors and learners alike was a pointer or semi transparent marker tool for the board Some instructors use the sys tem s mouse pointer for referencing While visible in the classroom lecture the action is not stored for remote access However having to operate with a mode for pointing would put an extra burden on the instructor Very likely the 1Pie menu variants implementing hierarchical organization called marking menus are protected by patent KF98 They are often used in gesture based interfaces The menu is only displayed for beginning users and kept invisible for expert users who have already learned the stroke movements for different options 163 164 CHAPTER 9 OUTLOOK teacher would often forget about the tool The developers of Classroom Pre senter reported for example that in practice none of their instructors found a semi transparent highlighter useful AAS 04 A better approach
324. va Properties file format Two Properties files are of central relevance to the system The file for the configuration setup described in Section 3 1 controls the whole E Chalk application The other file contains the settings for a lecture recording changed by the setup dialog and read by the above mentioned subcomponents The entire application was written in Java GM96 and requires the libraries of Java version 1 3 or later The audio and video server components rely on the Oscar 70 implementation of the OSGi component framework When using the video component the Java Media Framework JMF 44 library is also needed See Chapter 5 for details 3 1 Main Configuration The general setup Properties are read from the standard Java system Proper ties and the E Chalk startup configuration file lt echalk install dir gt conf main conf stored in the Java Properties file format The entries define among others the locations of secondary files like bookmarks and online doc umentation may activate the debug output mode and give class names of components to load dynamically The property entries in the startup configuration do not need to define the entries as literal strings The entries may use other property entries which will be evaluated recursively when the application accesses the prop erty entry where faulty definitions which are due to circular references will be detected A property is referenced as lt property key gt fo
325. ve of Tivoli PMMH93 from Xerox PARC is to support informal business meetings of small groups on an electronic whiteboard It handles pen based writing drawings wiping and gestural editing Tivoli has grouping techniques based on automatic recognition of implicit structures and a flexible re grouping mechanism MCvM97 The interface is optimized for sorting cat egorizing and annotating whiteboards content Board strokes are represented as splines Gestures are used to select move and change the properties of ob jects shown on the board and to zoom in or out Scripts can be plugged in for additional stroke processing MvMC98a MvMC98b MvM00 Various people 1 5 PEN BASED OFFICE AND CSCW TOOLS 13 LiveWorks MeetingBoard 3 1 CAMTGFILES 2 MTG 1 Jane printers modems 2 Tim dialogs icons 3 Angie dispay 4 Bob netwerk 5 Larry testing windows debugging m mm Als RE ee Figure 1 7 Snapshot of the Xerox LiveWorks MeetingBoard the commercial version of Tivoli Picture from MCvMK95 can use the system by simultaneously running connected copies allowing for distributed work The original Tivoli system was developed for Sun based LiveBoards and Sun workstations A version named MeetingBoard was marketed for commercial LiveBoards controlled by Windows PCs see Figure 1 7 1 5 4 Flatland Flatland MIEL99 is another development of Xerox PARC for digitizing office whi
326. with a whitespace it must be escaped Entries may also be distributed over several lines as escaped line terminators are ignored in entry parsing In the standard E Chalk installation the echalk lecture conf file has extensive comments and a semantic ordering to assist novice user changing the settings using a text editor see Section 2 4 If the setup dialog would simply use the standard Java Properties load and store methods to make the key value pairs of changed settings persistent comments and ordering would get lost For this reason the E Chalk application represents the documents structure in an instance of echalk util PropertyDoc It reads in the complete string representation of a Property file and determines the character intervals of the keys and the corresponding values in this string A PropertyDoc object provides methods to replace the entry for a key to add new key value pairs and to write the document back all while preserving the complete structure Expert Mode For expert mode editing the PropertyDoc s string representation is loaded into an echalk util TextEdit instance which implements a graphical text editor with all the standard features The setup dialog is hidden and the text editor is shown instead When the text editor is closed it executes a callback method to show the setup dialog again The PropertyDoc for the setup dialogs settings is updated if the echalk lecture conf file has changed 3 3 Connecting Compute
327. xplanations via tooltips are unobtrusive and should be used wherever possible For more detailed explanations a context sensitive help should be used Ideally all texts are localized to the user s language Interfaces must heed the fact that people make errors routinely Nor88 With a possibility to undo any action users are provided with a low risk envi ronment It invites them to explore the program and promotes learning The users should be guided by the software Handling errors should be prevented in advance instead of returning error messages when they occur For example when the computer has no sound card the E Chalk setup option for recording audio is made inaccessible The corresponding input element is deactivated and grayed out User should not be burdened with technical work which it can be done by the system Guidance and avoiding an excess of choices greatly disburden users This is especially important for the board interface as the operating persons will concentrate on the task of lecturing Distracting them is very unfavorable This is an experience also reported with other lecturing tools for example the developers of the Classroom Presenter learned their lesson of parsimony when they observed that instructors were strikingly restrained in their use of Presenter s features AHP 04b While users should be guided they should always be in control They should be assisted in their tasks not constrained
328. y G FU 13 sum 303 Table 8 4 Courses and number of returned questionnaires for the quantitative winter term 2003 04 study E Chalk materials making it easier to revise material of a class one has missed The second comparative study is based on the data of the evaluations per formed every term at the department of Mathematics at Technische Universitat Berlin for all of its courses The study compared earlier data on four courses taught without E Chalk with data of the same subject taught by the same instructors but with E Chalk in the winter term of 2003 04 For the classes without E Chalk data returned by 366 students were gathered for the E Chalk lectures 431 questionnaires were filled out See Table 8 3 for a detailed break down of the numbers The main statistically significant results on E Chalk lectures are FKR 04b e Students judged E Chalk classes to contain more repetition of relevant subject matter The distribution of grades shifted away from too little repetition towards too much repetition e The instructor receives worse rating for his or her speech intelligibility Note that this concerns the speech in class as no audio was recorded Maybe the lecturers were too much involved in handling the E Chalk tech nology distracted from turning to the students and speaking out clearly e Students in E Chalk lectures consider instructors board writing to be less well structured This is most likely a consequence of the real
329. y by taking screen snapshots 104 CHAPTER 5 AUDIO AND VIDEO SERVERS Chapter 6 Tools Converters Add ons This chapter describes a number of sub components and stand alone tools of the E Chalk systems These include converters for the E Chalk formats E Chalk components implementing E Chalk API classes like the Launchable interface and board Chalklets as well as stand alone tools for working on recorded lectures Unless explicitly stated otherwise stand alone tools are realized as Java applications 6 1 Export to PDF As mentioned in Section 2 5 the E Chalk system can automatically produce a transcript of a board recording as an Adobe PDF file The board to PDF converter echalk tools pdf Board2PDF is called as a Launchable from the main E Chalk application but it can be also used as a stand alone application In a first phase the board data from a given lecture are parsed by the con verter to get the board image as it looks like at the end of the lecture Invisible actions like scroll events and drawings removed with undo are ignored all other board elements are kept in memory For line strokes the first phase also drops inner points which are collinear with their neighbors as they are not needed in statically painting pages For example connecting the sequence of points 0 0 1 0 7 0 8 0 8 1 will result in the same image as the sequence 0 0 8 0 8 1 E Chalk recordings store each point delivered by the mou
330. y five minutes any idea however great can be condensed to that time And if no ideas are available there can always be discussion Discussion is the vac uum that fills a vacuum If no one comes to your lectures or sem inars you can have a workshop and get colleagues involved They have to come and your reputation as an adequately popular teacher is saved John Kenneth Galbraith A Tenured Professor The system presented here offers the possibility of producing distance lec tures as a by product of classroom teaching The approach avoids the huge costs normally involved in courseware production Instructors are not required to adapt their traditional teaching style for the sake of producing distance learning materials However for teachers who want to enrich their lessons with multimedia elements the system provides a range of options from plain images to interactive animations The board is a new GUI metaphor At the time being the desktop is the dominating user interface a metaphor being designed for the small personal screen that is part of the usual work desk Even pen computing approaches which have become popular recently are considered mainly for personal displays In a teaching situation where a large display may be observed by a larger audience the board is the proper metaphor This way the relation between teaching tool teacher and students is preserved which has been proven to be valuable for centuries The audienc
331. y one to three screen heights When the user scrolls the board the E Chalk live server sends the action to the three clients and all offsets are adjusted accordingly The setup with the three special board Applets is defined in a custom HTML template see Section 3 7 for the live setup An optional E Chalk configuration entry specifies native commands to be executed directly before the recording session starts used in this case to launch a browser opening the live HTML page and starting the three clients 8 1 2 Uses for Remote Access It is also possible to create a recording without an audience and to publish it solely for remote access see for example Figure 8 5 This approach has been chosen by users to produce revision material of the subject all well as extra content to be learned as a homework and in at least one occasion to replace a class where a date collision occurred for the instructor The E Chalk software can also be used for synchronous remote access to the lecture Apart from experimental seminars shared between remote locations there was also a regular lecture taught at Freie Universit t Berlin from a remote location The instructor was in one place the audience in another To extend the communication capabilities E Chalk was used in combination with a video conferencing system Voice and video image were transmitted two way by video conferencing and at the same time the board content was sent to the audience by the E Chalk
332. y reach inconsistent states for example if it keeps track of the mouse pointer assuming these is only one mouse while receiving events from two Even if the internal logic can cope with the remote users events it will not resemble a replay of the Applet s behavior during recording As a summary replaying Applets in general is a hard problem Many of the problems disappear when the reproduction of the AWT events is dropped and the Applets are more used as an interactive element in the lecture to be operated by the individual learner However this does not fit well to the overall philosophy of E Chalk lecture recording where remote participants should get the same information as the listeners in the class room For these reasons the handling of Applets in E Chalk stayed at a very ex perimental stage 4 11 Event Storage 4 11 1 Encoding All board events are concurrently stored to a file named board events in the lecture recording directory Applets and images are referenced indirectly in the events file and stored in extra directories see below An event file is organized by lines 2 Everything is stored in plain text ISO Latin 1 encoding This makes the events files readable to humans a great advantage in debugging On the other side this results in higher bandwidth use for transmission than for a binary representation In practice the bandwidth consumed by the board 31E Chalk s event parsers allow any of the platform depende
333. yncs with i j i streamed to a 2 i audio data audio Applet BE streamed to video data streamed to board data slide commands loaded by loaded by control Applet i controls Applet code Figure 7 2 Overview of the client Applets for replay of recorded lectures The Applet parameters recognized by the client control panel are e seconds This is a mandatory parameter defining the length of the recording in seconds as a decimal integer The information is given to the control panel as parameter instead of reporting such a information with Masi method as E Chalk data streams do not report their total length at the beginning of the data e title This is an optional parameter defining the lecture title to be displayed e initfile The optional init file with the given path relative to the control panels code base defines a skin for the control panel The init file is a Java property file with property entries defining the position and sizes of the control panel s control elements as well as the positions and colors of text font including a shadow color given separately for the title text the time display and for warning messages printed at the bottom Also an image file which contains the control panel s background image with inac tive buttons and the images of the control elements buttons for pressed and for mouse over look is contained For the play pau
334. z on WinNT 2000 but can sometimes be speeded up to a rate of up to 200Hz USB mice have a default sampling rate of 125 Hz wireless mice often below that The data rates of commercial pen input devices tested by the author Numonics IPM whiteboard Hitachi StarBoard different Wacom Tablets range from 50 Hz to 80 Hz Specifications for high end graphic tablets Wacom Intous2 and Cintig state up to 205 Hz but in practice rates of about 110 Hz are produced 33l ogging mouse move events on Applets may produce even bigger events as the size de pends on the depth of the Applet s component tree see below for Applet event formats Because Applet support in E Chalk is rather rudimentary it is not analyzed here in detail 34See Section 4 8 1 35 Macros are nevertheless able to produce undesirably high data volumes by rapidly loading images A mechanism to limit the bandwidth in this scenario still needs to be introduced to the server board 36 A parser would be especially difficult to realize for the lecture repair tool described in 4 11 EVENT STORAGE 87 length events bytes topic min sec total s total s bubblesort capsule 81 12 16 8124 8 3 335297 455 5 quicksort capsule 82 20 51 12910 10 3 528955 422 8 wavelets 83 73 27 58661 13 3 2570274 583 2 colors 84 71 00 38535 9 0 1663785 390 6 two s complement 85 16 43 14352 14 3 596287 594 5 eigenvalues 80 102

An Electronic Chalkboard for Classroom and Distance Teaching

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