Developing Geospatial Literacy Through Experiential Learning
Contents
1. Close range photogrammetry requires multiple photos from varying angles to provide sufficient reference points and ample coverage of the artifact to be modeled in this case a 8 century stone carved altar from the Figure 4 AutoCalibation Grid Sheet Ancient Maya site of Copan Honduras Figure 5 PhotoModeler 5 0 User Manual 2004 Once the camera calibration is complete the photos of the artifact to be modeled are taken The higher the resolution of the digital images of the object the higher the measurement accuracy of the model therefore the ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 camera was set to obtain photos at the highest possible resolution Each photo required 15 2 MB of storage space Photograph 1 Photograph 2 Photograph 3 Marked Marked Marked Point Point Point A B GC Station 1 station 3 Station 2 Top view Plan Figure 5 Ideal Camera Stations Figure 6 A 3D Point Derived from Marked Points PhotoModeler Pro 5 0 User Manual 2004 PhotoModeler Pro 5 0 User Manual 2004 Referencing Photos Referencing 1s the process in which points referring to the same physical point on an object to be measured are marked These referenced marks are used to create a 3D point a point with a location in space for which x y z coordinates are solved and used to generate the 3D model Figure 6 Referencing requires that points be marked on a reference photo 1 e the photo to which other photos will2. Iconography University of Oklahoma Press Norman and London Arias Veronica Theresa Runge Kuntz Heather M Richards Judith van der Elst and Richard P Watson 2004 Documentation and Virtual Modeling of Archaeological Sites Using a Non Metric Extreme Wide Angle Lens Camera In International Archives of Photogrammetry and Remote Sensing Vol XXXV Commission 5 Part B ISPRS Istanbul Turkey 2004 Burrough Peter A and Rachael A McDonnell 1998 Principles of Geographical Information Systems Oxford University Press New York New York ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 Edelson Daniel C Douglas Gordin and Roy D Pea 1997 Creating Science Learning Tools From Experts Investigation Tools Design Framework Paper presented at the Annual meeting of the National Association for Research in Science Teaching Oak Brook IL March 20 24 1997 Fash William L 2001 Scribes Warriors and Kings The City of Copan and the Ancient Maya Thames and Hudson London Goodchild Michael F and Donald G Janelle editors 2004 Thinking Spatially in the Social Sciences In Spatially Integrated Social Science edited by M J Goodchild and D G Janelle pp 3 22 Oxford University Press New York NY Hayden Dolores 1995 The Power of Place Urban Landscapes as Public History MIT Press Cambridge Mass Hohmann Vogrin Annegrette and Hasso Hohmann 1982 Die Architektur Von Copan Academic Publishers Graz Kwan Me
3. be referenced and then on subsequent destination photos A marked point with the same location must be marked on at least two photos in order to generate a 3D point however three is ideal Therefore it is essential to remember that when taking photographs of an object a common point should be visible in at least three photos Moreover these photographs must be taken at approximately 45 angles relative to one another We will refer to referencing later in the module as we mark and reference points PHASE II 3D MODEL DEVELOPMENT Now that a background on camera calibration and photo acquisition has been given the tutorial will turn to 3D model development on which a greater part of the module focuses After the camera has been calibrated and the digital photographs acquired phase III begins This phase is comprised of seven steps They are as follows 1 Setting the approximate project size and measurement units Describing the camera parameters Importing initial photograph images Marking and Referencing points Processing Adding new photos points lines surfaces etc Doing measurements or exports le a ae STEP 1 Navigate to the PhotoModeler Pro icon double click to open and to create a New Project click on the File tab on the Main Menu The Project Wizard will open Choose a Standard PhotoModeler project and click Next Read the steps in the Project Wizard and click Next The Project Settings need to be entered Select the appropriate
4. introduce students and professionals to spatial reasoning while simultaneously serving as a data collection and analytical tool We will present a pilot module on cost effective and time efficient close range photogrammetry that focuses on but is not limited to the discipline on anthropology This module uses experiential learning to facilitate student oriented learning by integrating theory with practice INTRODUCTION In recent years the use of geospatial technologies has become widespread in many professions however the teaching of geospatial thinking in academia is still in its formative stages Given that natural and cultural phenomena take place in space we contend that geospatial thinking a synthesis of spatial concepts methods technologies and applications must be an essential and integral part of social science education Burrough and McDonnell 1999 Goodchild and Janelle 2004 Hayden 1995 Kwan and Lee 2004 The nature of spatial thinking necessitates hands on experiential learning that allows students to acquire and apply problem solving skills and analyze relationships at different scales and across disciplines Geospatial technologies such as Geographic Information Systems GIS Global Positioning Systems GPS and Remote Sensing provide tools that facilitate experiential learning ultimately enriching geospatial understanding among students Researchers and educators have begun to highlight the significant impact television v
5. introduce students to close range remote sensing technologies and 2 facilitate the development of spatial literacy among students It is part of a larger effort to promote the use of GeoScience and geospatial technologies in order to enrich student learning Lock 2003 van der Elst et al 2006 http www csiss org SPACE CULTURAL BACKGROUND The archaeological site of Copan the largest Ancient Maya center in the southeast periphery of the Maya lowlands is located in the Copan Valley of Honduras about 14 km east of Guatemala Figure 1 Its main architectural complex the Principal Group Figure 2 was the setting for many regime organized ritual and political acts that served to legitimize and reaffirm dynastic power by linking dynastic rulers to the past and to the supernatural Fash 2001 Webster 2002 This civic ceremonial center is comprised of monuments and ancestral temples that provide archaeological data for many interpretations about Copan s sociopolitical and ideological arenas Altar Q located in Copan s West Court which was erected by Copan s last dynastic ruler in AD 775 about a half century prior to the Maya collapse offers an interesting artifact to carry out a close range photogrammetry project Figure 3 Figure 2 Principal Group at Copan Insert illustrates West Court Hohmann and Vogrin Hohmann 1982 i a ri r 4 k C mexico A Figure 1 Archaeological Site of Copan Honduras
6. measurement settings based on the object to be measured e g kilometers meters centimeters etc in this case Altar Q Hint Altar Q dimensions are east west 152 cm north south 147 cm height 70 72cm top 132 cm east west x 126 cm Calculate approximate size of Altar Q based on longest diagonal and enter the information Click Next STEP 2 The Camera Wizard opens Given that the calibration has already been done click the option A calibrated camera or a camera previously used in PhotoModeler and click Next Browse for the calibration file It is stored in C Photogrammetry_Module FullAutoCalibration_Plotter pmr and click Next Carefully review the information in the Camera Information Dialog Figure 7 Remember that the parameters displayed are critical to the project s success See Calibration section Click Next ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 Camera Wizard STEP 3 In the Photo Import Wizard add the Camera Review If any of the information is incorrect use the back button now or photographs digital images to the project by go to the Camera Information Dialog after the camera has been created clicking on the Add Remove Images button Click co PEGs eee A on the Change Directory button navigate to aoa E mn C Photogrammetry_Module Images folder and Fomet Siew O om BIOS select an image All images in the folder will Principal Poit x E40 mY ROSE automatically be added to the left si
7. DEVELOPING GEOSPATIAL LITERACY THROUGH EXPERIENTIAL LEARNING A CLOSE RANGE PHOTOGRAMMETRY MODULE Heather M Richards Veronica Arias Judith van der Elst Department of Anthropology University of New Mexico Albuquerque New Mexico 87131 heathmr unm edu arias unm edu jvdelst unm edu ABSTRACT Many scholars professionals and students have begun to employ geospatial analysis in their research however the teaching of geospatial thinking especially beyond the discipline of geography is still in its formative stages Geospatial thinking a synthesis of spatial concepts methods technologies and applications is an essential and integral part of the social sciences Studies show that today s students require teaching strategies dedicated to experiential learning that facilitate knowledge acquisition by making use of their unique development skills heavily grounded in visualization and spatial perception This paper focuses on the unique role geospatial technologies such as Geographic Information Systems GIS Global Positioning Systems GPS and Remote Sensing can play in the development and enrichment of geospatial understanding These technologies serve as teaching tools to develop innovative educational approaches and applications to promote spatial literacy providing skills and knowledge that are essential to decision making problem solving and successful academic and professional careers We propose to develop several modules that
8. adapted from Ferguson and Rohn 1990 Figure 3 Photographs of Altar Q in West Court in Principal Group Copan Richards 2005 ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 CLOSE RANGE PHOTOGRAMMETRY MODULE Close range photogrammetry a remote sensing technique to acquire data from photographs can be used to record and collect data on archaeological features and artifacts These data in turn can be used to create 3D computer simulated models from which measurements can be derived mass and volume illustrated and varying visual spatial perspectives explored In this module photographs of Altar Q will be ingested into PhotoModeler Pro 5 0 a photogrammetric software package to demonstrate the process of creating a simplistic 3D model of an archaeological artifact The process of digital photo documentation and 3D model development involves three major phases The first involves calibrating the camera and lens The second phase is to acquire the images and the third is to digitally process them in a photogrammetric software package in this case PhotoModeler Pro 5 0 PHASE I CAMERA CALIBRATION Camera Diagnostics The camera used to acquire the digital images for this project was a Nikon Coolpix 5700 non metric digital camera A normal lens with a focal length ranging from 8 9 71 2 mm was used however a fixed focal length of 8 9 mm was used to standardize the shots and provide a relatively wide angle setting without using a
9. ct As Altar Q Copan Continue selecting additional marked points using Photo 1 as the source photo Once a sufficient number of points have been selected to adequately cover the visible surface select Photo 2 as the Source Photo and then select Photo 3 Photo 4 and so on until all photos have been used For brevity s sake select approximately 35 40 reference points Remember to select points that will give shape to the object e g select points along the edges and corners of the altar STEP 5 After a sufficient number of points have been selected the model will be processed A processing dialog is used to define Camera Stations 1 e the position of and the direction the camera is facing at the time of exposure of a photograph and orient the photos Click on the Process 4 button on the Referencing Toolbar The Processing dialog box will open Figure 10 Click on each of the tabs to study the diagnostics of the project In this case the accuracy potential based on the audit details is High Click on the Process Tab to run the project Processing steps Options Reasons Ref Check Audit Summary Audit Overview Audit Photo Audt Ponts Reference Checker 1 has removed 2 points from processing Accuracy Potential based on Audit Details 0 9 444igh 1 No orientation nor Inv Camera 5 tion HI of Mest 5 4 2 3D globa optimization PAE aa IS Jext Suggestion Natel caibraiah At the current Proi
10. de of the Images created by E pivls by 1704 pies Add Remove Photographs dialog box Select the Fiducials photos required to carry out the project by clicking on the photos hold the shift key to select multiple photos and then click the double arrow wa ow m button to add selected photos to project There will be a total of eight photographs used in the project Figure 8 Notice that the photos selected provide varying angles and viewpoints of the altar which is essential to create an accurate 3D model See Acquiring Photos Click Next PhotoModeler confirms that these are the images to be used in the project Confirm and click Next Three of the seven steps required to create a 3D model have been completed Click the Finished button to move to Step 4 STEP 4 Now that the calibration and photos have been added to the project it is time to mark and reference points which is typically the most labor intensive 1 e time consuming phase of the project As mentioned above referencing is critical as it allows for the creation of 3D points Figure 8 Altar Q Project Images Navigate to the Referencing menu and select Reference Mode A new toolbar is added to the screen DE Ax e a 8 EE Marked points 1 e common points among the photos will be manually identified and used to link the images Ideally marked points should be visible on at least three photographs in order to achieve the highest possible accuracy Two poin
11. ect Marking Quality of 5 00 pixels these ngle photo misteferences were identified pant ID phato 4 Reterence Checker 2 wall not run ID 29 7 and these possible multiple phato misreaferances were identihed point ID 24 Constraints will be processed Figure 10 Processing Dialog for Referencing Marked Points After the project has finishing processing a Total Error is calculated and a Project Status Report is generated Study the report What types of errors have been introduced into the project The Project Status Report below indicates that a marking residual in the project is greater than 5 00 Figure 11 A Marking Residual is a residual error or the difference between where the user marked a point and where the program expects the point to be located The residual is critical as it represents the amount of difference between an expected and calculated value For example if you expected a certain measurement to come to 3 45mm but the actual final result was 3 41mm then the residual or residual error would be 0 04mm ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 Status Report Project Name Altar Q Copan pmr Problems and Suggestions 1 Project Problems 1 Problem The largest point residual in your project Point33 6 08 is greater than 5 00 Suggestion In normal projects strive to get all point residuals under 5 00 pixels If you have just a few high residual points study them on each
12. i Po and Jiyeong Lee 2004 Geovisualization of Human Activity Patterns Using 3D GIS A Time Geographic Approach In Socially Integrated Social Science Edited by Don Janelle and Michael Goodchild pp 48 66 Oxford University Press Lock G R 2003 Using Computers in Archaeology towards virtual pasts Routledge London amp New York Runge Kuntz Theresa Heather M Richards Veronica Arias and Judith van der Elst 2004 Using Aerial Photography and Geographic Information Systems for Spatial Temporal Change Detection Analyses of Historical Sites In Proceedings of the ASPRS Annual Conference Denver May 2004 Silverman Linda Kreger 2003 The Power of Images Visual Spatial Learners In Gifted Education Communicator 34 1 14 17 38 41 van der Elst Judith Heather Richards and Veronica Arias 2006 Employing low budget geospatial methods incultural resource management In Recording Modeling and Visualization of Cultural Heritage edited by E Baltsavias A Gruen L van Gool and M Pateraki pp 465 472 Taylor amp Francis Webster David 2002 The Fall of the Ancient Maya Solving the Mystery of the Maya Collapse Thames amp Hudson New York ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006
13. irtual display video games and other computer simulated environments have made on the younger generation including those attending universities and colleges throughout the United States Studies show that today s students require innovative educational strategies that encourage knowledge acquisition by making use of contemporary development skills heavily grounded in visualization and spatial perception Spatial literacy is critical however learning materials and teaching strategies utilizing traditional lecture based formats often forgo other more creative strategies that are better suited to teach geospatial thinking such as scientific visualization which offers a more creative approach to facilitate learning through visual representations of complex data and spatial relationships Edelson and Gordin 1997 Silverman 2003 We believe that close range photogrammetry a non invasive technique to acquire data from photographs offers a means to introduce students to geospatial technologies and develop spatial thinking In this paper we present a pilot module that introduces students to the concept of close range photogrammetry by allowing students ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 to create a 3D computer simulated model of an archaeological artifact Such an approach utilizes experiential learning integrating theory with practice and promoting spatial literacy In general this classroom module serves two objectives 1
14. os Now lines and surfaces will be added to the 3D model 3D Viewer Options Visibility Settings Advanced By object type By layer W Points Layer name Wisible W PointID s Point Tags Default Iw W Lines Cures Edges Surfaces Cylinders shaded x Surface Draw Control lines Cam Stations Control points E p Cancel Help Figure 12 3D Viewer Option Dialog Box STEP 6 Close the 3D Viewer and navigate to the Marking tab on the Main Toolbar Select the Mark Lines Mode tool which will mark lines on the project In this case we will mark the edges of Altar Q in order to delineate the altar s shape Click on a referenced point using the Mark Lines tool move to the next appropriate point and click on it to create a line Continue this process until an outline of the altar has been generated Open a New 3D Viewer Uncheck the Point ID s and Click OK Figure 13 ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 An outline of Altar Q has been created To add mass to the altar surfaces will be generated Minimize the 3D Viewer and navigate to the Marking tab on the Main Toolbar click on Surface in the dropdown list and click on Path Mode The Path Mode option constructs a surface using a closed loop of 3D objects such as points lines edges and curves The loop becomes the outer boundary of the surface and the interior is interpolated Interpolation is key concept in many types of spa
15. photo to ensure they are marked and referenced correctly If many of your points have high residuals then make sure the camera stations are solving correctly and that your are using the best camera parameters possible Information from most recent processing Last Processing Attempt Sun Jan 29 10 08 35 2006 PhotoModeler Version 5 2 3 Status successful Total Error Number of Processing Iterations 4 Number of Processing Stages 2 First Error 3 261 Last Error 3 296 Figure 11 Project Status Report for Processing of Altar Q Copan Project In this case Point 33 has a marking residual greater than 5 00 Studying the residual and adjusting Point 33 s position on each of the marked photographs can correct the error Notice that the Total Error is 3 296 This correlates to a measurement error of 3 296 cm Is a 3 3 cm accuracy sufficient Explain After studying the project status results click the Write to text file tab Remember it is very important to store information about any project The Project Status Report provides valuable data about the project Once all errors have been reviewed and corrected it is time to view the project in the 3D viewer Navigate to Project on the Main Menu click on Open a 3D Viewer and select New 3D Viewer In the 3D Viewer Option dialog check the boxes for Points Point ID s and Lines Figure 12 Click OK At this phase the project is comprised only of the points that have been marked on the phot
16. rol points or axes constraints to orient the model Navigate to the Project tab on the Main Menu and select Scale Rotate The 3D Scale and Rotation dialog box opens Click on the Scale tab select cm type 152 in Distance box and click on a horizontal line e g red line on the altar Click Define Now click on the Rotate tab Define the 3 parameters by selecting the appropriate lines for each required category Figure 16 Click OK Open a new 3D Viewer Click on the Measure tool Click on several of the lines to study the accuracy of the measurements for the various faces of Altar Q Click on a surface Notice that the measurement tool automatically calculates surface area Figure 17 The software utilizes the camera calibration information along with photogrammetric algorithms to compute distance and measurements in the photos to build the 3D model Play around with the 3D model Rotate the model on its axis Take several measurements How do these measurements compare to those provided above for Altar Q See STEP 1 Given this level of accuracy what types of questions can be addressed Do you find the computer simulated 3D model useful If so how is it useful Does it allow you to answer questions that could not be answered using a 2D image or drawing 3D Scale and Rotation Overview Translate Scale Rotate Distance 152 om Define Pick 2 items in a combination of points lines edges or camera stations then pre
17. ss Define 3D Scale and Rotation Overview Translate Scale Rotate Horizontal Horizontal r Vertical left to right front to back bottom to top Define Define Define lw wf E r p3 2 Pick 2 points or cam stna and press Define for 2 axes Cancel Help Figure 16 Setting 3D Scale and Rotation for Altar Q ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 Figure 17 Using Measurement Tool in PhotoModeler Synopsis Now to review the phases and steps involved in creating a 3D computer simulated model using close range photogrammetry Phases I and II were done in a previous lab field project Phase III involved seven steps First the project size and measurement units were entered Second the camera calibration characteristics were entered into the PhotoModeler software program Third the photographs or digital images taken in the field were downloaded and imported into the software Fourth common points among the photographs were marked and referenced Fifth the images were oriented and processed to generate a virtual 3D model comprised solely of points Sixth lines and surfaces were added to the model to give it mass volume and texture Seventh measurements of length width height and surface area were calculated CONCLUSIONS This paper sets forth a close range photogrammetry module as a means to exemplify the utility of hands on experiential learning in developing spatial literac
18. tial analysis Spatial interpolation is the process of calculating unknown values from a set of sample points with known values that are distributed across an area ESRI Virtual Course Pasa Meme l Figure 13 3D Model of Altar Q illustrating Points and Lines After selecting the Path Mode tool maximize the 3D Viewer Click on the Options tab and check Surfaces In the surfaces box choose Shaded Texture will be added later Click OK Given that each side of Altar Q is a rectangle each surface will be comprised of four lines Click on the four lines that comprise a side they will be highlighted in red as they are selected Remember the lines must be clicked consecutively as the Path Tool is being used Continue creating surfaces until a box like shaded shape has been created Figure 14 Figure 14 Surface Creation Using Shaded Option Now click on the Options tab to open the 3D Viewer Options dialog In the Surfaces box click the dropdown arrow and select Quality textures This will overlay the Altar with the original photos used in the project Figure 15 ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 Figure 15 3D Model of Altar Q with Textured Surface STEP 7 We now have a 3D computer simulated model of Altar Q however before the model can be used to take measurements the 3D Scale and Rotation must be set Scale is achieved by adding a known distance between two points in the model Rotation uses cont
19. ts may be acceptable if the photos are already well referenced 1 e sufficiently linked to one another However the use of only two points is not recommended as it will most likely reduce accuracy The marking and referencing stage uses a Source Photo and a Destination Photo Click on the down arrow in the left box of the newly added toolbar Referencing Toolbar and select Source photo 1 Now click on the down arrow in the right box of Referencing Toolbar and select Destination photo 2 Figure 9 Use the zoom and pan tools F r to select a common point between the two photographs While selecting points try to cover the full extent or visible surface of the object in order to increase the project s accuracy That is select at least one marked point near each corner of the object and a few throughout the interior to produce the best results ASPRS 2006 Annual Conference Reno Nevada May 1 5 2006 O et OB ms A Maas Se Bo oO ge ote dy whee eet ute 9 m z a f Sepo Oestination photo 2 z R vf a amm E Reference 1 124 5 O90N1949 oriented M EI Photo 2 1 4 5 DSOM1950 oriented n Pag 7 3 Ya mia 2 a Figure 9 Marking and Referencing Points Now select a second destination photo and mark the same point Remember that to generate a 3D model from the photographs requires the same point to marked on at least 2 photos however three or more is optimal Before referencing additional points Save Proje
20. wide angle lens The camera has a resolution of 5 0 megapixels Calibration What is it Why is it important The calibration of the camera to the PhotoModeler software is necessary to remove the distortions in the images that are created by the lens Removing the distortion has a major advantage in that it permits higher measurement accuracy in the 3D model PhotoModeler requires all photos to maintain fixed settings for three parameters in order to use the software for 3D models These parameters are 1 same camera 2 fixed focal length and 3 standard image width pixels and image height pixels The parameters for this project are Coolpix 5700 camera with normal lens at most wide angle setting Fixed focal length 8 9 mm and Image Height 1704 pixels and Image Width 2560 pixels For brevity s sake the calibration for this project has already been completed A standard camera Calibration Grid calibration using the Calibration Grid provided by PhotoModeler was used to calibrate the Coolpix camera Figure 4 The final calibration solved all of the internal camera parameters and produced a total error of 0 232 Filename FullAutoCalibration_Plotter pmr This correlates to an accuracy of approximately 23 cm However the actual accuracy of the final 3D model depends on the parameters and precision of marked and referenced points in the final project and not only on the calibration used for the project PHASE IT ACQUIRING PHOTOS
21. y among students It provides a step by step guide to camera calibration photo acquisition and 3D model development using the principles of photogrammetry It is our goal to develop additional modules centered on geospatial methods and analysis taking advantage of recent advances in geospatial technologies such as Geographic Information Systems GIS and Global Positioning Systems GPS We believe that spatial thinking is essential to solve many of today s scientific and social issues and thus it is necessary to develop innovative and creative learning materials and teaching strategies that integrate geospatial perspectives in education especially the social sciences The module itself fits within the broader framework of Computer Assisted Learning CAL which offers many advantages to traditional learning These include 1 computer simulation allowing for dynamic interactive interfaces 2 virtual collections providing access to often restricted or unavailable objects and 3 online modules that reach a wider audience Lock 2003 This module along with other modules focused on spatial learning can be seen to complement classroom discussion on geospatial theory methods and applications and with further enhancement may be utilized for professional development and skill acquisition especially in regions with limited access to skilled educators e g developing countries REFERENCES Baudez Claude Francois 1994 Maya Sculpture of Cop n The
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