Sketch Based Retrieval User Manual
Contents
1. Figure 16 Detail of second SBR GUI depicting the All Results button and part of results area scroll bar Additionally the SBR application offers another method to consult the results returned by the system Trough using this method users are able to see all twelve drawings simultaneously The All Results window depicted in Figure 17 is opened when users Page 15 of 17 SmartSketchea User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al press the All Results button marked in Figure 16 This window displays simultaneously all the drawings returned by the query SIBR All Results 5 a oC jo Ke gy Oo o O O O o Fo Close amp Figure 17 All Results Window which displays all twelve results To display any on of the returned drawings with more detail the SBR application provides the Selected Drawing window shown in Figure 18 This window pops up whenever one of the returned drawings is clicked i e the pen is pressed down over it This operation works similarly with the drawings displayed in the results area or with the ones displayed in the All Results window SBR Selected Drawing OFJ TERET EH Ee Att Hue e tt aaa E iie fol ia Open Drawing sbr data drawings current art_pi_8852 dxf d 0 630412 Drawi2. e Buttons Area To control the program are used a few buttons described below These buttons are arranged in two parts of the SBR user interface The more frequently used ones are placed at the bottom of the window and the other two are on top right Page 7 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al Sketching Area Additional Buttons Area WUSIBR Sketch amp Image Based Retrieval Similar Drawings Ready No results to display Query Progress Main Buttons Area Results Area Figure 6 Screenshot of SBR application The buttons within the buttons area allows user to control the application and are described below New Query Clears sketching area displayed results and loaded image Use this button to start sketching a completely new query Open Image Opens one image from a TIFF file and converts it to vector format drawing it on the sketching area Use this to perform Image Based queries or to mix images and sketches to specify a query Opening an image clears existing image sketch and results View Image Opens a new window that shows the digitized image When no image has been loaded this button is disabled Undo Performs the undo operation on the sketch removing the last stroke drawn by the user If no sketch exist this button are disabled Redo Discards previous undo operations This button i
3. field displays the value of last identifier in database plus one However the user can change any of these fields but changes on classification parameters must be done carefully In order to give some feedback to the users during processing dbBuilder application has a log window where the status of the classification is displayed Additionally a log file is also saved for later analysis After checking that values on the fields are correct the user can press the Build button to start the classification of drawings in DXF format that are in the specified folder Descriptors of these drawings are then added to the database in specified folder If no database exists there a new one will be created but the folder must exist 6 SBR The SBR application graphical user interface is divided in three main areas as depicted in Figure 6 These areas are described below e Sketching Area Users sketch the query in this area Additionally the vector version of the digitized drawings is also displayed here If users want to edit that drawing they sketch over it It is also possible to select just part of the sketch to use as a query e Results Area In this area are displayed the drawings returned by the queries Since each query returns twelve drawings and it is not feasible to show them all at once only five drawings are displayed simultaneously The scroll bar located at right allows browsing up and down trough the twelve drawings
4. 13 of 17 SmartSketcher User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al SIBR Image Processing Eg oigna ssl EJ E J Binay E z Timed Last Step Conversion to Gray Scale Next Step Contrast enhancement Skip gt gt View Histogram Cancel Figure 14 Screenshot of image processing window Next are briefly described the buttons on the image processing window Proceed Continues the image processing performing the next step indicated above Back Undoes the last step processed Skip Whenever the next step is optional this button is enabled and gives the user a chance to speed up the vectorization process by skipping that step View Histogram Opens a new window that displays the histogram of the image This is mainly useful to help experienced users choosing the more efficient options during vectorization Cancel This button provides a way to abort the vectorization discarding the loaded image and every processing already made When the vectorization is finished the result is drawn by the system on the sketching area and is from now on considered as a sketch Therefore the procedure to execute a query with it is exactly the same as with a hand made sketch Page 14 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al 6 4 Mixing Images and Sketches Since digitized images after vectorization ar
5. dashed white line When a region is selected users can still sketch freely on any part of the sketching area inside or outside of the selected region However only the strokes drawn inside the selected region will be considered for query purposes 6 3 Using Images The SBR system allows searching for a drawing based on its paper version without using sketches To that end it is necessary to have a flatbed scanner connected to a computer to digitize the paper drawing Additionally the correspondent image acquisition software must be installed on that machine and it must be able to save the acquired images in TIFF format Almost all scanners available will digitize drawings without problems Even the cheaper flatbed scanner solutions will work well for the retrieval purposes After the drawing has been scanned and saved in a TIFF file it can be used by the SBR application To that end the Open Image button must be pressed and a file browser dialog is shown In this dialog the user can select which TIFF file will be used A major advantage of this approach to use paper drawings lays on the possibility of using remotely digitized images which can be shared over a network or even sent by e mail GUSIBR Sketch amp Image Based Retrieval HOR Help rd Exit a Similar Drawi O O a Q Q O wings HENRO Ready Query Progress Figure
6. user can specify as drawing editor the widely used AutoCAD if it is installed on the computer Page 9 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al Database Path Specify where is located the database This allows having the database in any accessible folder Note that this folder only needs to have read permissions Thus it is possible to have multiple databases in different location or a shared database in a remote computer Parameters set by users in Configurator are stored in the operating system environment Thus they remain defined until further changes These parameters are used by the SBR application to know where the database is stored and which drawing editor must use 6 2 Using Sketches To perform a query using only sketches user must draw on the sketching area a rough approximation of the wanted drawing or part of it and submit that sketch as a query to the retrieval system To that end after finishing the sketch the user must press the Execute Query button When the desired drawing does not appear within the twelve results returned by the system it is always possible to edit the drawing removing adding or changing some features and then submit the new version of the sketch This can be repeated as many times as user whishes until the desired drawing is found To restart sketching from scratch the New Query button must be pressed In this case the sk
7. visual elements without deleting them making further searches easier To select a region user must change from Skecth Mode to Select Mode and then use the pen to specify the region To enter Select Mode it is necessary to press the pen over the sketching area without moving for two seconds After entering select mode the cursor over the sketching area will change to a cross and the stroke will appear in dashed white as depicted in Figure 10 fe ET KS TER E Figure 10 Selecting part of a sketch To discard the selection the pen must be pressed over the sketching area maintained without moving for a couple of seconds and then lifted up From now on the whole sketch will be used as a query Whenever users want to select or unselect any other region the procedure is the same as described before and is resumed below Select Gesture 1 Press pen down 2 Wait two seconds without moving changes to Select Mode 3 Specify region by moving pen 4 Lift pen up changes to Sketch Mode Unselect Gesture 1 Press pen down 2 Wait two seconds without moving 3 Lift pen up Page 11 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al After a region has been selected by the user the SBR switches immediately from Select Mode to Sketch Mode Now the sketching area outside the selected region appears with a darker background and its border is clearly identified by a
8. 11 Using a digitized image to retrieve a technical drawing As soon as the image file is opened a new window is displayed Figure 14 Here the users will control the vectorization process In some steps of the vectorization the system will ask the user about methods or parameters to apply during processing Every one of these questions is accompanied by a suggestion When users are not sure of which option produces the best results they can follow the suggestion made by the system However if at any time of the vectorization process the resulting image does not satisfy the users they can undo one or more steps and then repeat them with different options Depending on the quality of the scanned drawing not all steps of the vectorization process are required Thus the users can sometimes skip a step they consider Page 12 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al unnecessary if it is an optional step see Figure 12 This way the time spent in the vectorization process could be shortened a i K ia 7 ii w A o a ontrast Edge eee A Binary Noise TA i an z gt es 5 9 A Binarization y nary Not Ho Thinning Polygonization 3 5 2 ae ii i SE J Enhancement if Enhancement Af Reduction Figure 12 Vectorization steps Experienced users can consult the histogram of the image and use their knowledge to help them choosing properly the more efficient methods and p
9. INFORMATION SOCIETY TECHNOLOGIES IST PROGRAMME information society technologies SmartSketches 5 Sketch Based Retrieval User Manual Project acronym SmartSketches Project full title SmartSketches A Multimodal Approach to Improve Usability in the Early States of Product Design Contract no IST 2000 28169 DELIVERABLE D22b WORKPACKAGE WP6 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al TECHNICAL REPORT TITLE Sketch Based Retrieval User Manual AUTHOR Manuel Joao da Fonseca Alfredo Ferreira Jr DATE September 2004 PAGES 17 VERSION 1 0 WORKPACKAGE 6 DELIVERABLE D22 KEYWORDS User Manual Sketch Based Retrieval CIRCULATION Consortium Table of Contents BOVER TEV cena E E E 1 2 RELA TED DOCUMENTS cerisier a Aa R a 2 HFPRINCIFLESOF OPERATION osscsscccscvsvwsscasdessesecesdasundadsssesee TEE ENEE 2 dt INSTALLA TION sessasescccssasacavsweedaqnusaincesssesetesascevaneesansaunscnacesoasesessaacuoeosuseandacueeiaaasencweanssy angsunausnsesacsscanstasennsssaesesaees 5 S DBBUILDER se siatssaceastessdecensesadescendssects sates sskeestaecdadsaged cia sdeiessensdiedsadectassesedsZeansseadsshscsGabesdeutadectasdesseuZeenseuadssasssdebesdontaxes 5 Ge DBR A EPE A E IIOS OE E OE A O EOE O T O IT O A O 7 6l CONFIGURA FTON ssvessssessedassctetssascessataisesssiqsissesanceadsassessatassopscacgnsassgsiccnssdigsuccssbesegeneapasnasesassseascacnasgsensasanadsaneesess
10. arameter to apply during the image vectorization On the other hand novice users can perform their choices by simply following the suggestions made by the system or using a trial and error approach Figure 13 is illustrates a vectorization of a drawing depicting the evolution of part of the drawing In this case the user has an original image in grayscale format performed both contrast and edge enhancement steps and then executed a binarization using fixed threshold However the yielded binary image has low quality Therefore the user went back one step and tried a different binarization method which produced a better binary version of digitized drawing Then user applied the noise reduction and thinning steps obtaining a good final result fo ay jo Binary using fixed threshold Original grayscale Enhanced contrast and edges 16 e i Binary using region averaging Binary after noise reduction Thinned binary image Figure 13 Example of drawing vectorization detail To allow an effective control of the vectorization process the image processing window depicted in Figure 14 shows the current status of the vectorization On the top of the window is indicated which version of the image is displayed below Additionally this also shows which steps were performed and which were skipped Under the image are shown the last step performed and the following one At the bottom of the window a set of buttons allows the control of the process Page
11. classified too Only drawings saved in DXF format with the dxf extension will be considered If the folder does not exist an error message will appear and no processing will occur By default this field contains the location of the last drawings classified Database Folder Specifies the folder where is located the database If no database exists on that folder a new one is created Otherwise the classified drawings are added to the database In this case some care must be taken when specifying the initial identifier Notice that current user must have write permissions on database folder in order to perform successfully classification of drawings Initial ID Here is specified the value of the initial identifier for the drawings to classify This identification number is necessary because the drawings stored in the database are identified by it Since the database can already have classified drawings the identifier of the new ones must not conflict with the existing drawings identification Moreover users might want to group drawings by identifier according to some criteria Page 6 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al When dbBuilder starts all the fields are already filled with default values The Drawings Folder field contains the last used value In Database Folder appears the location of the database currently active in retrieval application The Initial ID
12. e considered as a sketch the users can treat it exactly the same way they treat a sketch Thus it is possible to sketch over it adding new shapes delete existing ones and select only part of the sketch to use as a query Mixing sketches and vector drawings give the users the capacity to derive more complex queries They can add new elements to vectorized drawings by sketching new shapes or they can delete entities by using a simple gesture command This way they can start with a digitized drawing and then apply editing commands to refine it l HUSIBR Sketch amp Image Based Retrieval OE Help 2 Exit Similar Drawings Figure 15 Mixing images and sketches to retrieve a technical drawing Figure 15 presents a query that was refined by adding shapes to the original figure in order to detail more information The figure illustrates also a selection of part of the drawing to use as a query without deleting the remaining elements 6 5 Viewing Results Each query returns twelve drawings similar to the sketch submitted by the users These drawings can be viewed in the results area of the main window of SBR application However only five of them can be displayed simultaneously To consult the remaining drawings users must use the scroll bar of the results area shown in Figure 16 Results Area Scroll Bar All results button
13. er solutions based on textual queries are not satisfactory because they force designers to know in detail the meta information used to characterize drawings Worse these approaches also require humans to produce such information manually when cataloguing data In contrast to the textual organization the SBR system is able to index and retrieve mould drawings based on content This system uses a visual classification scheme based on shape and spatial relationships which are better suited to this problem because they take advantage of users visual memory and explore their ability to use sketches as a query mechanism SBR system performs automatic classification of existing drawings of parts and allows users to retrieve one of them either by sketching it using a digitized image or even mixing both techniques To that end the SBR system uses a calligraphic interface to allow specifying queries trough hand drawn sketches These sketches can be an approximate representation of the desired part In response the system returns a set of candidate drawings similar to the query Moreover it is able to convert raster images into vector drawings and use these as queries The SBR system will reduce the development time of new moulds since it allows easy and fast re use of previous drawings and solutions Furthermore it offers to engineers and designers a powerful new way to classify and retrieve drawings without using textual data or annotations More
14. es when searching for a drawing Examples for bad and good queries are depicted in Figure 4 In this case the ought drawing is composed by several shapes However there are three of them that dominate it Both sketches portray such shapes but while the good one respects drawing topology and accurately represents the three dominant polygons the bad one fails on topology and is far less accurate Thus when the good query is submitted to the system the wanted drawing is returned at first attempt On the other hand when the bad query is submitted the SBR is unable to find the ought drawing in the database Even after some changes and repeated submissions the desired drawing were not returned In such case the best thing to do is to clear the sketch and start a new one from scratch Please remember that the capacity of drawing good sketches comes with the experience Therefore it is common that first sketched queries are not completely successful However after some time using the system users will be able to quickly sketch good queries To that end it is necessary that they can identify which shapes Page 4 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al are relevant in a drawing and how they can sketch them in order to create a similar representation Concluding we underline that to take full advantage of SBR system users must use it fre
15. etching area will be deleted and drawings displayed in results area will be cleared Executing a query usually takes several seconds sometimes even a couple of minutes depending on the complexity of the sketch and of the existing drawings and on the size of the database At the bottom right of the window a progress bar gives some feedback about the evolution on the classification and retrieval process Additionally the current step of the process is also displayed on the status bar n WUSIBR Sketch amp Image Based Retrieval SmX Help rd Exit Lad Similar Drawin gs Figure 8 Using a sketch to retrieve technical drawings 6 2 1 Delete Gesture While editing a sketch the user can delete part of it To that end the Delete gesture must be used The Delete gesture consists on drawing a zig zag stroke over the shapes to delete as depicted in Figure 9 Page 10 of 17 SmartSketche Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al Deleting stroke on sketch Sketch after deletion Figure 9 Using delete gesture to remove a stroke 6 2 2 Select Gesture When the sketch is too complex too big or have undesired shapes user can select just part of it to use as a query To accomplish this SBR application provides a tool for selecting a region on the sketch and submitting it as a query Thus it is possible to discard
16. ings unless you are using a remotely shared database which already contains all drawings To classify existing drawings must be used the dbBuilder tool This application can be launched by executing the command sbr builder on the folder where the system is installed Please note that the dbBuilder can be executed as many times as necessary and not only after the installation 5 dbBuilder In order to retrieve drawings using the SBR system it is necessary to classify them in first place To that end the SBR system includes a classification application called dbBuilder This application classifies existing drawings by creating logical descriptors based on features extracted from drawings Currently topological and geometric information are extracted from polygons detected in drawings Page 5 of 17 SmartSketches Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al The classification of a technical drawing might take from a few seconds to several minutes depending of its complexity Therefore the classification of a large set of drawings may take several hours However since this is an operation that will be performed only once for each drawing users can execute it in batch mode To that end the dbBuilder offers the possibility of automatically classifying a set of drawings without user intervention Users only need to specify where drawings can be found the location of the database and the identifier for
17. ng info Figure 18 Displaying selected drawing The Selected Drawing window displays not only a larger version of the drawing but also its location Furthermore from this window it is possible to have access to more information about the drawing or open it using the CAD tool specified during configuration of the SBR system Next the buttons of this window are described Open Drawing Opens displayed drawing using an external editor such as AutoCAD This editor must have been previously specified by user in Configurator Drawing Info Opens the Detailed Drawing Information window depicted in Figure 19 which contains detailed information about the selected drawing Close Closes the Selected Drawing window Page 16 of 17 SmartSketche Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al fl Detailed Drawing Information Jo Filename drawing dxf Location d shared data drawings Size 13 240KB Created 12 Feb 2004 12h01m Modified 12 Feb 2004 12h01m Additional Information Author Alfredo Ferreira Jr Subject Part P5438 Top View Project Smartsketches Keywords Mould Plastic Owner INESC ID Contractor IST Figure 19 Screenshot of Detailed Drawing Information window Page 17 of 17
18. over it well free users from browsing through large and deep file directories or recalling part numbers dates locations or client and designer names 2 Related Documents More information about the SBR system can be found within the Smartsketches project in the following deliverables e D4 CWP1 Consolidated Requirements and Analysis e D13 WP7 Technical Drawing Retrieval by Sketches Usability Tests e D14 WP7 Prototype Usability Tests e D22 WP6 Using Sketches to Retrieve Drawings Additionally several scientific publications had been published describing technically the approach implemented by this system References for such publications can be found in deliverable D22 3 Principles of Operation The SBR system classifies each drawing or sketch based on its visual features These features are extracted from spatial relationships and geometric properties of detected polygons Thus it is important that when sketching the users keep in mind that what matters for classification are polygons i e closed polylines Therefore users must be aware that when a shape is meant to be a polygon the strokes that compose it must touch in order to produce a valid polygon For instance shapes Page 2 of 17 SmartSketche Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al depicted in Figure 1 are meant to be two polygons This sketch is supposed to represent a triangle inside a trapezoid but user failed
19. quently and became proficient in sketching queries An expert user will be able to quickly sketch a query that returns the ought drawing in the first attempt 4 Installation Installation of the SBR system is a straightforward process However prior to start it the users are advised to check if their computer fulfills the requirements for running this technical drawing retrieval solution Minimum System Requirements Pentium III 800 MHz with 256 MB of memory recommended 512MB Pen and Tablet or other digitizing device recommended pen and tablet Flatbed scanner for local acquisition of paper drawings About 100 MB of free disk space without user drawings database To install the SBR system please follow the steps described below 1 Insert the installation CD in your drive 2 Open the folder SBR on the CD 3 Execute the file file SBR INSTALL EXE 4 Indicate where you wish to install the SBR system After installation was finished users can execute the Configurator to define a different location for the database and to specify which external tool must be used to edit the drawings To run the Configurator users must locate the folder where the SBR system was installed and then execute there the command sbr config Please read section 6 1 to know more about system configuration When the system is fully installed and configured according to users preferences it is a good idea to start classification of existing draw
20. s 9 6 2 USING SKET HES wssscesesssaesssonctaceasnsarscseasaisneesasupenvaneddsingsbessesavasensacenssneeeslsoosseuiassvnveesenaseosqeusaasaweabensadenbabesvedentes 10 62 DELETE GESTURE siswsrccassscsevacasstscsvsasadsnorsesensentpiundetnntcenesevavesheacisesiestbenssensienssrasioveessateasepsancaseienavanessneeaseaseess 10 6 2 2 DUE FP GESTUR E cnan E E 11 m USING IMAGES sirida ia ER aA aaa a 12 04 MIXING IMAGES AND SE ETC HES piinia dridi a NaS 15 05 VIE WING RESULTS cociran aaia Na a EAEEREN Eaa AANA 15 1 Overview The widespread use of CAD tools in the mould industry during the past two decades made the creation and edition of drawings easier increasing the number of mould drawings available in electronic format Even though reusing drawings often saves time manually searching for them is usually slow and problematic requiring designers to browse through large and deep file directories or navigate a complex maze of menus and dialogs for component libraries Moreover current CAD systems provide only conventional database queries or direct manipulation mechanisms to retrieve past technical drawings Page 1 of 17 SmartSketchea Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al Most solutions to this problem use textual databases to organize the information These classify drawings by keywords and additional information such as designer name style date of creation modification and a textual description Howev
21. s enabled only when the last operation was an Undo ae Page 8 of 17 SmartSketcher Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al Execute Query Ee Uses the current sketch as a query to the drawings database Show All Results HE Opens a new window that displays all twelve results returned by the query While no results exist this button is not enabled Opens the help Exit Quits the application 6 1 Configuration To configure the SBR application it is necessary to run the SBR in Configurator mode Since classification of the SBR is rarely used there is unnecessary to have a direct way to access this operation mode Therefore to enter in Configurator mode the application must be run with the c or config parameter L SIBR Configurator X Drawing Editor C Program Files Bentley Microstatian95 Browse Database Path sbr data databases current Browse Cancel Accept Figure 7 Screenshot of Configurator The SBR Configurator has two fields that can be changed by the user After changing them user must click on Accept button to activate the changes made Next we briefly describe these fields Drawing Editor Specify which application is used to edit the drawings returned by the query This application will be called by the SBR system when the user clicks on Open Drawing button to edit the desired drawing For instance
22. tended until it touches the other as illustrated in Figure 3 Likewise if any extremity of other stroke in sketch is near the last stroke drawn the older stroke is extended in order to make them touch Page 3 of 17 SmartSketcher Z User Manual d22 user guide sbr v3 doc 06 10 2004 M J da Fonseca et al Scribble drawn by user Scribble after auto completion Figure 3 Example of multi stroke auto completion Understanding how auto completion behaves is important to take full advantage of this precious feature of the SBR sketch editor Thus new users are encouraged to try it for a couple of minutes in order to get used to it before start sketching queries Additionally users must explore the gestures supported by it explained in Section 6 2 Besides being familiar with the sketching editor it is fundamental that users are able to recognize a good query from a bad one A good query returns the desired drawing while a bad one does not Unfortunately there are no simple heuristic to define a good query There are only a few basic principles that the user must have in mind such as drawing closed polygons respecting the topology of the drawings and sketch with some accuracy According to experiments made with users the ability to produce successful queries came with experience Ought drawing Bad query Good query Figure 4 Example of sketches that produces bad and good queri
23. the first classified drawing the system will then do the processing autonomously SIBR dbBuilder x Drawings Folder Rtr afi MsC dxfs currentlayered Browse Database Folder sbr data databases plates Browse Initial ID 500 A Removed 0 small polygons Polygon Simplification took 691 ms Determination of Topological relationships between polygons took 601 ms Detected a total of 2 polygons Algorithm ended at 06 09 04 15 17 21 51144 ms File processed successfully in 51774 ms Start processing file WRtraff MsC dxfs currentlayered plate 1 2 chx Converted 388 entities from dxf file Algorithm started at 06 09 04 15 17 22 Conversion to lines started at 06 09 04 15 17 22 Conversion to lines took 10 ms Original set of lines have 960 elements Detected 6 intersections Segment Intersection Removal took 261 ms Set of lines after intersection removal have 51 elements Seqment Ordering took 10 ms Hot pixel determination started at 06 09 04 15 17 22 Found 512 hot pixels i pixel determination ended at 06 09 04 15 17 22 took 20 ms Figure 5 Screenshot of dbBuilder The dbBuilder application depicted in Figure 5 has a small form on top of the window with three fields to specify the working parameter of the classification module These fields are described below Drawings Folder Specifies the folder containing drawings to classify If this folder has subfolders drawings on these will be
24. to close properly the triangle Thus when submitted for classification only one polygon represented in red were detected and considered for feature extraction Doo Original Sketch Sketch after Polygon Detection Figure 1 Only closed shapes on sketch are considered as polygons To help users sketch closed polylines the SBR system includes a stroke auto completion feature This feature automatically completes the strokes drawn by the user if seems that they are meant to be closed polylines or touch another near stroke Thus there are two modalities in the auto completion provided in the SBR application the single stroke auto completion and the multi stroke auto completion Stroke drawn by user Auto completed stroke Figure 2 Example of single stroke auto completion The Single Stroke Auto Completion is invoked immediately after the user ends a stroke i e when user lifts the pen This completion process analyses the stroke performed by the user and if one of the extremities are close to any part of the stroke it completes it This is done by extending the stroke until it closes over itself An example of such completion is depicted in Figure 2 After the stroke is completed by the Single Stroke Auto Completion the Multi Stroke Auto Completion method is called This method compares the last stroke with the whole sketch If any of its extremities is near another stroke in the sketch the last stroke is ex
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