Calhoun: The NPS Institutional Archive
`
`Theses and Dissertations
`
`Thesis and Dissertation Collection
`
`1998-09-01
`
`VRML terrain modeling for the Monterey Bay
`National Marine Sanctuary (MBNMS)
`
`Leaver, R. Greg
`
`Monterey, California. Naval Postgraduate School
`
`http://hdl.handle.net/10945/9154
`
`Exhibit 2005
`Bradium Technologies LLC - patent owner
`Microsoft Corporation - petitioner
`IPR2016-00449
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`ILEY KNOX LI8RAI
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`iTRREV CA I
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`NAVAL POSTGRADUATE SCHOOL
`Monterey, California
`
`THESIS
`
`VRML TERRAIN MODELING FOR THE MONTEREY
`BAY NATIONAL MARINE SANCTUARY (MBNMS)
`
`by
`
`R. Greg Leaver
`
`September 1998
`
`Thesis Advisor:
`
`Associate-Advisor:
`
`Don Brutzman
`Rex Buddenberg
`
`Approved for public release; distribution is unlimited.
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`REPORT DOCUMENTATION PAGE
`
`Form Approved
`OMB No. 0704-0188
`Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction,
`searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send
`comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to
`Washington headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA
`22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188) Washington DC 20503.
`
`1. AGENCY USE ONLY
`
`2. REPORT DATE
`3. REPORT TYPE AND DATES COVERED
`September 1998
`Master's Thesis
`4. TITLE AND SUBTITLE : VRML Terrain Modeling for the Monterey Bay National
`Marine Sanctuary (MBNMS)
`6. AUTHOR
`R. Greg Leaver
`
`5. FUNDING NUMBERS
`
`7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)
`Naval Postgraduate School
`Monterey, CA 93943-5000
`
`9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)
`
`N/A
`
`8. PERFORMING
`ORGANIZATION REPORT
`NUMBER
`
`10. SPONSORING /
`MONITORING
`AGENCY REPORT
`NUMBER
`
`11. SUPPLEMENTARY NOTES
`The views expressed in this thesis are those of the author and do not reflect the official policy or position of the
`Department of Defense or the U.S. Government.
`12a. DISTRIBUTION / AVAILABILITY STATEMENT
`
`12b. DISTRIBUTION CODE
`
`Approved for public release; distribution is unlimited.
`13. ABSTRACT (maximum 200 words)
`This thesis develops an online model of the topographic terrain of Monterey Bay National Marine Sanctuary
`(MBNMS) seafloor. Written in the Virtual Reality Modeling Language (VRML), the model is an interactive 3D
`application composed of hundreds of topographic tiles linked together to form a mosaic of the bay.
`Low-resolution
`tiles are traded for higher resolution tiles as the viewer gets closer to the terrain.
`Important contributions include a naming convention for autogeneration of interlinked files, test usage of
`proposed metadata conventions linking VRML and the extensible Markup Language (XML), demonstrated use of the
`GeoVRML Working Groups proposed QuadLOD node, and a preliminary 3D navigation icon for terrain interrogation
`and wayfinding. Terrain data was produced from registered, smoothed and subsampled bathymetric sonarscan
`results. Because the model is geo-referenced with the Universal Transverse Mercator (UTM) coordinate system, a
`user can easily add scientific content or data to a selected location of the MBNMS in a manner analogous to adding
`2D content to an HTML page. Thus, the user can place 3D content anywhere in the MBNMS in geographic context
`merely by specifying the geographic coordinates and depth of the content in standard VRML syntax.
`Future work includes improvement of metadata interoperability, navigation icon user testing, and
`autogeneration of image-based texture tiles for scientific visualization.
`14. SUBJECT TERMS
`World Wide Web, Virtual Reality Modeling Language (VRML), Large-Scale Virtual Environments
`(LSVEs), Monterey Bay, 3D Graphics Modeling
`
`15. NUMBER
`OF PAGES
`126
`
`17. SECURITY
`CLASSIFICATION OF REPORT
`Unclassified
`
`18. SECURITY CLASSIFICATION
`OF THIS PAGE
`Unclassified
`
`19. SECURITY
`CLASSIFICATION OF
`ABSTRACT
`Unclassified
`
`16. PRICE
`CODE
`
`20.
`LIMITATION
`OF ABSTRACT
`UL
`
`NSN 7540-01-280-5500
`
`Standard Form 298 (Rev. 2-89)
`Prescribed by ANSI Std. 239-18
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`Approved for public release; distribution is unlimited
`
`VRML TERRAIN MODELING FOR THE MONTEREY BAY NATIONAL
`MARINE SANCTUARY (MBNMS)
`
`R. Greg Leaver
`Lieutenant, United States Navy
`B.S., Oklahoma State University, 1987
`
`Submitted in partial fulfillment of the
`requirements for the degree of
`
`MASTER OF SCIENCE IN INFORMATION TECHNOLOGY MANAGEMENT
`
`from the
`
`NAVAL POSTGRADUATE SCHOOL
`September 1998
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`ABSTRACT
`
`This thesis develops an online model of the topographic terrain of Monterey Bay
`
`National Marine Sanctuary (MBNMS) seafloor. Written in the Virtual Reality Modeling
`
`Language (VRML), the model is an interactive 3D application composed of hundreds of
`
`topographic tiles linked together to form a mosaic of the bay. Low-resolution tiles are
`
`traded for higher resolution tiles as the viewer gets closer to the terrain.
`
`Important contributions include a naming convention for autogeneration of
`
`interlinked files, test usage of proposed metadata conventions linking VRML and the
`
`extensible Markup Language (XML), demonstrated use of the GeoVRML Working
`
`Groups proposed QuadLOD node, and a preliminary 3D navigation icon for terrain
`
`interrogation and wayfinding. Terrain data was produced from registered, smoothed and
`
`subsampled bathymetric sonarscan results. Because the model is geo-referenced with the
`
`Universal Transverse Mercator (UTM) coordinate system, a user can easily add scientific
`
`content or data to a selected location of the MBNMS in a manner analogous to adding 2D
`
`content to an HTML page. Thus, the user can place 3D content anywhere in the
`
`MBNMS in geographic context merely by specifying the geographic coordinates and
`
`depth of the content in standard VRML syntax.
`
`Future work includes improvement of metadata interoperability, navigation icon
`
`user testing, and autogeneration of image-based texture tiles for scientific visualization.
`
`12
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`VI
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`.
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`TABLE OF CONTENTS
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`I.
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`INTRODUCTION
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`A. BACKGROUND
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`B. MOTIVATION
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`C. OBJECTIVES
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`D. THESIS ORGANIZATION
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`II.
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`BACKGROUND AND RELATED WORK
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`A. INTRODUCTION
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`B. BACKGROUND
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`1
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`Monterey Bay National Marine Sanctuary
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`2. Monterey Bay Modeling Group
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`3. Coordinate Systems Used
`
`4. What is VRML?
`
`C. RELATED WORK
`
`1. GeoVRML Working Group
`
`2 Seamless Solution's Terrain Navigator
`
`3. SIGGRAPH CARTO Project
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`4. VRML Terrain Generators
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`5. Synthetic Environment Data Representation & Interchange
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`Specification (SEDRIS)
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`6. Other Existing VRML Terrain Models
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`D. SUMMARY
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`III.
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`PROBLEM STATEMENT
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`A. INTRODUCTION
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`B. RESEARCH FOCUS
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`C. DESIGN CONSIDERATIONS
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`1. Transitions Considered
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`a. "SwapTile" Transition
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`b. "QuadTile" Transition
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`c. "QuadSwapTile" Transition
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`2. Transition Chosen
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`D. SUMMARY
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`IV.
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`BATHYMETRIC TERRAIN DATA
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`A. INTRODUCTION
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`B. DATA PROCESSING
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`1. Data Source and Gridding Process
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`2. Partioning the Datasets
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`3. How Resolutions Were Determined
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`C. FILE NAMING CONVENTION
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`D. METADATA
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`E. SUMMARY
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`V.
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`JAVA PROGRAMS FOR DATAFILE CONVERSION TO VRML
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`A. INTRODUCTION
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`B. CREATEVRMLTILE PROGRAM: GENERATING INDIVIDUAL
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`VRML TERRAIN TREES
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`1. Read Data File Name
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`2. Read Metadata
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`3. Read Elevation Data ......................................................................... .. 28
`3. Read Elevation Data
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`4. Geographically Position Tile ............................................................ .. 28
`28
`4. Geographically Position Tile
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`5. Write VRML Syntax
`5. Write VRML Syntax ......................................................................... .. 28
`28
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`C. CREATEVRMLTREE PROGRAM: GENERATING LINKING
`C. CREATEVRMLTREE PROGRAM: GENERATING LINKING
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`VRML TERRAIN TREES
`VRML TERRAIN TREES .......................................................................... .. 28
`28
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`1. Read Children File Names ................................................................. .. 29
`1. Read Children File Names
`29
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`2. Construct Parent and Children Relationship ...................................... .. 29
`2. Construct Parent and Children Relationship
`29
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`3. Write VRML Syntax
`3. Write VRML Syntax .......................................................................... .. 29
`29
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`D. SUMMARY ................................................................................................. .. 29
`D. SUMMARY
`29
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`VI.
`VI.
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`VRML SCENE DETAILS
`VRML SCENE DETAILS .............................................................................. ..3l
`31
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`A. INTRODUCTION ........................................................................................ .. 31
`A. INTRODUCTION
`31
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`B TERRAIN TILES .......................................................................................... .. 31
`B TERRAIN TILES
`31
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`l.Metadata ............................................................................................. .. 31
`1. Metadata
`31
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`2. Positioning ......................................................................................... .. 33
`33
`2. Positioning
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`3. Navigation Icons ................................................................................ .. 34
`34
`3. Navigation Icons
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`4. Elevation Grids .................................................................................. .. 35
`4. Elevation Grids
`35
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`5. Textures .............................................................................................. .. 36
`36
`5. Textures
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`C. TERRAIN TREES ....................................................................................... .. 36
`C. TERRAIN TREES
`36
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`1. Switching ........................................................................................... .. 36
`36
`1. Switching
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`2. Viewpoints ......................................................................................... .. 37
`37
`2. Viewpoints
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`D. SUMMARY ................................................................................................. .. 38
`D. SUMMARY
`38
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`VII. EXPERIMENTAL RESULTS ..........................................................................39
`VII. EXPERIMENTAL RESULTS
`39
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`A. INTRODUCTION ....................................................................................... .. 39
`A. INTRODUCTION
`39
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`B. MONTEREY BAY TERRAIN MODEL DATABASE .............................. .. 39
`B. MONTEREY BAY TERRAIN MODEL DATABASE
`39
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`C. PERFORMANCE RESULTS AND USABILITY TESTING
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`1. Performance Aids
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`a. Vertical Exaggeration
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`b. Reducing File Size by Rounding
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`2. Performance Results
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`D. USER ACCESS AND NAVIGATION
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`E. EXAMPLE INTEGRATION OF CONTENT
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`1. Georeferencing
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`2. Adding Content
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`F. SUMMARY
`
`VIII. CONCLUSIONS AND RECOMMENDATIONS
`
`A. RESEARCH CONCLUSIONS
`
`Generating VRML Syntax
`
`1
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`2. Viewpoints
`
`3. Rendering
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`4. Georeferencing and Content
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`B. RECOMMENDATIONS FOR FUTURE MBNMS TERRAIN
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`MODEL WORK
`
`1. Normals to Eliminate Tile Seams
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`2. Modified QuadLOD Node
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`3. Navigation Icons to Control Other Transitions
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`4. Return of the Navigation Icons
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`5. Other MBNMS Model Future Work
`
`C. OTHER LSVE FUTURE WORK
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`APPENDIX A: SCRIPTS USEDTO GRID DATA SETS
`APPENDIX A: SCRIPTS USEDTO GRID DATA SETS ....................................... ..57
`57
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`APPENDIX B: SCRIPT USED TO PARTITION DATA SETS ........................... ..61
`APPENDIX B: SCRIPT USED TO PARTITION DATA SETS
`61
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`APPENDIX C: CREATEVRMLTILE JAVA PROGRAM
`APPENDIX C: CREATEVRMLTILE JAVA PROGRAM ................................... ..63
`63
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`APPENDIX D: CREATEVRMLTREE JAVA PROGRAM
`APPENDIX D: CREATEVRMLTREE JAVA PROGRAM .................................. ..77
`77
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`APPENDIX E: EXAMPLE VRML TERRAIN TILE FILE STRUCTURE
`APPENDIX E: EXAMPLE VRML TERRAIN TILE FILE STRUCTURE ......... ..8l
`81
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`APPENDIX F: EXAMPLE VRML TERRAIN TILE SCENE GRAPH
`APPENDIX F: EXAMPLE VRML TERRAIN TILE SCENE GRAPH ............... ..89
`89
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`APPENDIX G: EXAMPLE XML FILE
`APPENDIX G: EXAMPLE XML FILE ................................................................... ..93
`93
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`APPENDIX H: EXAMPLE VRML TERRAIN TREE FILE STRUCTURE
`APPENDIX H: EXAMPLE VRML TERRAIN TREE FILE STRUCTURE ....... ..95
`95
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`APPENDIX I: EXAMPLE VRML TERRAIN TREE SCENE GRAPH
`97
`APPENDIX 1: EXAMPLE VRML TERRAIN TREE SCENE GRAPH ................97
`
`LIST OF REFERENCES ............................................................................................ ..99
`LIST OF REFERENCES
`99
`
`INITIAL DISTRIBUTION LIST .............................................................................. ..101
`INITIAL DISTRIBUTION LIST
`101
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`1
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`LIST OF FIGURES
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`2.1 Monterey Bay National Marine Sanctuary
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`2.2 Focus of GeoVRML Working Group
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`3.1 Tile Transitions
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`3.2 Tile Transition Types
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`3.3 Implementation of QuadSwapTile Transition
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`4.1 File Naming Convention
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`5.1 Typical Metadata Excert From Gridded Text Data File
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`6.
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`Example XML Keys and Key Values Used in Metadata Node
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`6.2 A Navigation Icon
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`6.3 A Single Elevation Grid (File N353610.W1232629.070.051.1000.seabeam.wri) .35
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`6.4 QuadLOD Excerpt (File N353610.W1232629.070.051.1000.tree.wri)
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`7.1 Directory Structure of MBNMS Terrain Model Database
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`7.2 Applying Vertical Exaggeration
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`7.3 3:1 Scaling Example (File N353611.W1223609.070.051.1000.seabeam.wri)
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`7.4 1:1 Scaling Example (File N353611.W1223609.070.051.1000.seabeam.wri)
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`7.5 Entry Viewpoint of MBNMS Terrain Model
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`7.6 Georeferencing VRML and UTM Coordinate Systems
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`LIST OF TABLES
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`4.1 File Partition Characteristics by Resolution for Entire MBMNMS Footprint
`
`6.1 Quadlod Node Proximity Sensor Values
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`7.1 Terrain Tile Dataset Characteristiics
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`7.2 Terrain Tree Dataset Characteristics
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`7.3 Rendering Time for Resolutions
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`7.4 Tile Switching Values (depth)
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`ACKNOWLEDGEMENTS
`
`To my wife Sandra, my daughter Lauren, and my son Chase, thank you all for
`
`supporting me in this endeavor. I love and treasure each of you more than mere words
`
`can say. To Don Brutzman, I offer my thanks for your contagious inspiration,
`
`enthusiasm, and guidance. To Ray McClain, I am indebted to you for your assistance in
`
`this project. I couldn't have done it without your help.
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`I.
`
`INTRODUCTION
`
`A.
`
`BACKGROUND
`
`This thesis investigates how the Virtual Reality Modeling Language (VRML) can
`
`be used to model the seafloor topography of the Monterey Bay National Marine
`
`Sanctuary (MBNMS). By creating a topographic model of the MBNMS using VRML, a
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`three-dimensional representation of the sanctuary can be accessed over the World-Wide-
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`Web (Web) by anyone using a VRML-enabled web browser or standalone VRML
`
`viewer. A VRML-enabled browser means a browser configured with a VRML plug in
`
`such as Cosmo Player for PCs (Silicon Graphics, 98). Rapid recent progress in this field
`
`means that many new opportunities are available.
`
`B.
`
`MOTIVATION
`
`Numerous scientists and researchers are collecting data and building
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`environmental models about Monterey Bay. Regional research partnerships using a
`
`Large Scale Virtual Environment (LSVE) for Monterey Bay will make it easy for
`
`scientific content about Monterey Bay to be placed and accessed online. Building a
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`Monterey Bay terrain model is a dramatic way to encourage scientists to their work in
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`three-dimensional (3D) space and on the Web. New insights and new research
`
`collaborations are likely. A new paradigm for publication of scientific data and analytic
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`results is possible.
`
`C.
`
`OBJECTIVES
`
`The goal is to make the addition of a user-selected portion of MBNMS terrain in a
`
`3D VRML scene as easy as adding a background image to a 2D HTML page. Thus, it is
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`

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`hoped that this effort will make it easy for scientific content about Monterey Bay to be
`
`placed and accessed online, in a 3D geographic context.
`
`Although many scientists are conducting research in Monterey Bay, bathymetric
`
`terrain scenery is not easily available. VRML makes 3D graphics accessible to any
`
`desktop. Constructing a LSVE for Monterey Bay may dramatically enhance ongoing
`
`regional research collaborations. An additional objective is for the model to support
`
`variable resolutions of gridded data. "Variable resolutions" essentially means that as a
`
`viewer gets closer to terrain, the resolution of the terrain increases to provide superior
`
`granularity.
`
`D.
`
`THESIS ORGANIZATION
`
`The remaining chapters of this thesis are organized as follows. Chapter II
`
`provides the background for the effort, introduces a few cartographic concepts, and
`
`touches on some related work being done. Chapter III presents the problem statement
`
`and covers design considerations for a feasible solution. Chapter IV provides a look at
`
`bathymetric data sources and describes the gridding process used to create simple gridded
`
`text data files. Chapter V shows how these elevation grid terrain text files can be
`
`processed by a Java program to produced VRML world files. Chapter VI discusses the
`
`specific VRML constructs produced by the Java programs that implement the MBNMS
`
`terrain model, including 3D navigation/information icons. Chapter VII considers
`
`experimental results, examines user access, and shows how users can integrate their 3D
`
`content and MBNMS terrain. Chapter VIII presents thesis conclusions and provides
`
`recommendations for future work.
`
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`II.
`
`BACKGROUND AND RELATED WORK
`
`A.
`
`INTRODUCTION
`
`This chapter examines pertinent background work that motivated the construction
`
`of a terrain model for the MBNMS and introduces the basic concepts of VRML. It also
`
`discusses other work being done to produce 3D topographic models, and provides a quick
`
`look at a tool evaluated by the author that creates 3D topographic scenery in VRML from
`
`elevation data sets.
`
`B.
`
`BACKGROUND
`
`1.
`
`Monterey Bay National Marine Sanctuary
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`Beginning 1 1 km north of San Francisco's Golden Gate Bridge, the MBNMS 1
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`extends 260 km south along the California coast to Cambria Rock in San Luis Obispo
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`County. The Monterey Bay National Marine Sanctuary contains the nations greatest
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`diversity of marine life and habitat. East to west, the sanctuary stretches 152 km and
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`holds one of the world's largest ocean canyons: the 10,663 ft. deep Monterey Canyon.
`
`Thus, this area provides unparalleled opportunities for marine scientists based at nearby
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`research institutions such as Moss Landing Marine Laboratories (MLML), Monterey Bay
`
`Aquarium Research Institute (MBARI), and NPS. Figure 2.1 illustrates the MBNMS
`
`region. The sanctuary was established to enhance resource protection and preserve the
`
`natural beauty within its boundaries.
`
`More information on the MBNMS is available at http://bonita. mbnms. nos. noaa.gov/
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`275 km
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`220 km
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`165 km
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`110 km
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`55 km
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`0km
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`170 km
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`135 km
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`90 km
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`45 km
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`0km
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`Figure 2.1. Monterey Bay National Marine Sanctuary (MBNMS Web Site, 98)
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`2.
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`Monterey Bay Modeling Group
`
`Interest in developing computerized processes and models to assist with studying
`
`and managing the sanctuary led to the formation of the Monterey Bay Modeling Group.
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`In 1993, the MBNMS Research Advisory Committee, under the sponsorship of the
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`National Oceanic and Atmospheric Administration (NOAA), prepared a research plan
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`which outlined the research priorities and management goals for the sanctuary. This plan
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`outlined the objectives of the Monterey Bay Modeling Group, an ad hoc group of
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`individuals interested in computer modeling and affiliated with various MBNMS research
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`organizations, including NPS. Listed among the objectives was the goal for the
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`development of a computerized model of the sanctuary (NOAA, 93). The model, it was
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`hoped, would ultimately function as an oceanographic scientific database archival and
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`retrieval system, which could be overlain on a 3D physiographic representation of the
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`MBNMS. The model would be networked for use by scientists, engineers, planners,
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`managers, and the general public. Unfortunately this group was only active for two
`
`years. Recent discussions indicate that technology has advanced sufficiently to enable
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`further scientific collaborations.
`
`3.
`
`Coordinate Systems Used
`
`In terms of latitude and longitude, the MBNMS occupies a square region between
`
`35°30' North and 38° North latitude, and 123°15" East and 121° East longitude. Since
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`latitude and longitude are commonly used measures, they are included in the model's
`
`metadata and file-naming convention. Universal Transverse Mercator (UTM)
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`coordinates, which specify a location as a distance north (Northing) and east (Easting)
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`2 A good explanation of the UTM coordinate system is available at: http://geography. tqnm/msub 1 4. htm
`
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`from a zone's meridian measured in meters, are also frequently used in cartography. In
`
`terms of the UTM system, the MBNMS lies between Northing coordinates of
`
`3,940,000m to 4,200,000m, and Easting coordinates of 460,000m to 612,000m. Because
`
`UTM coordinates are in meters rather than degrees, UTM measurements can easily be
`
`converted to VRML coordinates that are default units in meters. This capability allows
`
`gridded elevation data and scientific content to be positioned relative to their real world
`
`location in the MBNMS model.
`
`4.
`
`What is VRML?
`
`VRML - the Virtual Reality Modeling Language - is a 3D graphics scene
`
`description language that enables a scene builder to create dynamic worlds and sensor
`
`rich virtual environments on the Internet. VRML enables users to animate objects in
`
`worlds, making them move; it also enables users to play sounds within worlds, interact
`
`with worlds and, control and enhance worlds with scripts, or small programs (Ames, et.
`
`al., 97). VRML provides a standardized, portable, and platform-independent way to
`
`render dynamic, interactive, 3D scenes across the Internet (Brutzman, 97).
`
`A VRML file generally ends with extension ".wrl". This file is a textual
`
`description of a 3D world. A VRML file contains nodes that describe shapes and their
`
`properties in the virtual world. These nodes make up the building blocks - VRML
`
`constructs - which create the 3D scenery in a virtual world. For cartographic models
`
`such as this project, one of the principal VRML constructs is the ElevationGrid node,
`
`which can be used to create a 3D representation of the terrain. The terrain itself is
`
`described by a data set containing bathymetric depth values. Each sampled depth value is
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`
`.
`
`associated with a pair of gridded 2D coordinates. An excellent overview of how VRML
`
`can be applied to cartography can be found in Fairborn and Parsley (97).
`
`C.
`
`RELATED WORK
`
`1
`
`GeoVRML Working Group
`
`To provide a forum for discussions of the representation and exchange of properly
`
`geo-referenced data in VRML advance, the GeoVRML Working Group was established.
`
`One of the forum's goals is to establish VRML as a standard for the representation and
`
`exchange of 3D geographic and cartographic data. The GeoVRML mailing list is
`
`maintained as part of the GeoVRML Working Group of the VRML Consortium by SRI
`
`International. Figure 2.2 shows the primary issues of interest and concern of the working
`
`group.
`
`•
`
`Coordinate systems - measurement systems including the Geodetic and
`Geocentric systems used to specify locations on the surface of the Earth.
`• Time referencing - important for content that is timestamped with respect to a
`an absolute reference.
`
`•
`
`•
`
`•
`
`•
`
`Terrain representation - imagery usually represented in an array of numbers
`that represent topography in digital form.
`
`Levels of detail - the hierarchy of resoltions necessary to achieve acceptable
`rendering and performance for a LSVE
`Resolution and accuracy - factors limited by georeferencing VRML worlds to
`a coordinate system and by data storage issues.
`
`Data interchange - standardized data format and type to enable data exchangge
`and interoperability.
`
`Figure 2.2. Focus of GeoVRML Working Group (Iverson, 98)
`
`2.
`
`Seamless Solution's Terrain Navigator
`
`The Terrain Navigator is implemented entirely in Virtual Reality Modeling
`
`Language (VRML) for use on a low-cost Personal Computer (PC) to enable a content
`
`developer to integrate highly realistic terrain content with Web pages. This real-time
`
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`

`
`interactive visualization software is especially useful for collaborative review of database
`
`development throughout the design cycle or for entertainment purposes. (Seamless
`
`Solutions, 98).
`
`3.
`
`SIGGRAPH CARTO Project
`
`The "Carto Project" began in 1996 as a cross-organizational collaboration
`
`between the activities of the Association for Computing Machinery's Special Interest
`
`Group on Graphics (ACM SIGGRAPH) and the International Cartographic Association's
`
`(ICA) Commission on Visualization. The Carto Project explores how viewpoints and
`
`techniques from the computer graphics community can be effectively applied to
`
`cartographic and spatial data sets. This includes exploring how viewpoints and methods
`
`from cartography can enhance developments in computer graphics; especially those
`
`associated with the representation of geographic phenomena. These efforts will continue
`
`into 1999, in conjunction with the time frame of the ICA's Commission on Visualization
`
`(Rhyne, 98).
`
`4.
`
`VRML Terrain Generators
`
`Several commercial products exist that can automatically generate VRML terrain.
`
`To do so, generally these products import a dataset in a prescribed format such as Digital
`
`Elevation Model (DEM) and produce export a VRML file via a filter. Rapid Imaging
`
`Software offers a product called LandForm Gold (RIS, 98) that works like this. A copy of
`
`this software was evaluated by this author, courtesy of Mike Abernathy at RIS.
`
`LandForm Gold is a powerful 3D real-time terrain viewer for the Windows NT/95
`
`platform. This product allows a user to view geographical data in a three-dimensional
`
`J DEM files contain data of the elevation of the terrain over a specified area, usually at a fixed grid
`
`35
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`

`
`representation and move through the data in a natural and intuitive manner. The program
`
`accepts numerous file types and allows the user to superimpose an image of the area over
`
`the terrain. This effect of the image overlay combined with 3D data creates a strikingly
`
`realistic representation of the terrain, as landmarks and topographical features are
`
`dramatically revealed in 3D. As mentioned earlier, LandForm Gold also enables the user
`
`to create VRML models based upon the dataset read by the viewer. Other tools, such as
`
`Cybertrek (98) and Coryphaeus (98) are also available to create VRML terrain models,
`
`but were not evaluated by this author.
`
`5.
`
`Synthetic Environment Data Representation & Interchange
`
`Specification (SEDRIS)
`
`The SEDRIS Geographic Reference Model (GRM) has been proposed by the
`
`GeoVRML Working Group (discussed later) as a standard for VRML coordinate
`
`systems. SEDRIS is a reference model and software package that currently supports 12
`
`different commonly used world coordinate system convention, as well as tools to
`
`automatically convert reference marks between them. Coordinate system standards
`
`supported include Geodetic (GDC or latitude/longitude), Geocentric (earth centered
`
`Cartesian), Universal Transverse Mercator (UTM), and Lambert Conformal Conic
`
`(LCC). The proposal (GeoVRML, 98) was drafted by SRI International and is
`
`summarized here. It proposes two levels to employ VRML constructs that implement the
`
`SEDRIS standards. Level 1 consists of a means of entering geographical coordinates into
`
`VRML files so that the Cartesian VRML coordinates are generated with respect to a
`
`geographically referenced local coordinate system. Its use depends only on the
`
`interval, such as 1 arc-degree or 7.5 arc-minutes. DEM files are avilable (for a fee) from the U.S.
`Geological Survey at: httpJ/edcwww. cr. usgs. gov/webglis
`
`36
`
`

`
`availability of a library for converting from geographical coordinates in the GRM into a
`
`local Cartesian frame. Level 2 consists of an attempt to establish a means for
`
`automatically managing the relationships between the local Cartesian frames defined in
`
`Level 1 . It is intended as the enabling technology for seamlessly integrating accurately
`
`georeferenced worlds from a wide variety of sources. Since the constructs contained in
`
`the proposal are experimental at this time, they were not employed in the MBNMS
`
`Model. Nevertheless they remain an important area for future work.
`
`6. Other Existing VRML Terrain Models
`
`SRI International has developed a VRML terrain model of the Fort Irwin,
`
`California area. This terrain model has been distributed on CD-ROM and is also
`
`viewable on the Web (SRI, 98). It uses multiple levels of detail to change the terrain's
`
`resolution based upon the viewer's distance to the scenery. In 1997 RIS produced a
`
`model of the San Francisco Bay area (Abernathy, 98). This model was produced to
`
`convey topographical information to participants in the San Francisco Relay. By
`
`integrating Global Positioning Satellite elevation data with satellite and aerial imagery,
`
`the model displayed the terrain the event's course and scenery from a runner's point of
`
`view.
`
`A simple textured model of Monterey regional terrain is also available at
`
`http://ece. uwaterloo. ca/vrml98 .
`
`It provides background for the VRML 98 Symposium
`
`3D website
`
`D.
`
`SUMMARY
`
`This chapter explores the related work that preceded or motivated the creation of
`
`a model for the MBNMS. It places the sanctuary in a geographical context and presents
`
`10
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`37
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`

`
`the goals of the Monterey Bay Modeling Group. A brief overview of VRML provides
`
`some basic concepts of this scene-description language. Work related to VRML terrain
`
`development is considered and VRML terrain authoring tools are introduced - one of
`
`which is evaluated by the author. Additionally, some existing VRML terrain models are
`
`identified.
`
`11
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`38
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`12
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`39
`
`39
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`

`
`III.
`
`PROBLEM STATEMENT
`
`A.
`
`INTRODUCTION
`
`Although excellent commercial software exists for professional development of
`
`topographic models (both VRML and non-VRML) in 3D, these tools can be expensive
`
`and may require data sets to be in a proprietary format. Furthermore, the tools are not
`
`only necessary to generate the topographic models; they are also often required to be
`
`present on a user's console in order to view the models. By representing the model in
`
`VRML, an open solution to the problem of generating topographic data sets and
`
`subsequently viewing them is obtained. Anyone with a web browser and WWW access
`
`can potentially interact with the model. This chapter covers the problem of developing
`
`such an application. It then discusses the advantages of VRML as the basis for
`
`implementing a solution. Much of the chapter is devoted to an examination of the design
`
`issues considered in the development of a model solution.
`
`B.
`
`RESEARCH FOCUS
`
`In the last few years, advances in 3D modeling languages have made it feasible to
`
`develop the foundation for a 3D model of the MBNMS. VRML in particular enables the
`development of a model that can be viewed over the WWW on any platform with
`
`Internet access and a VRML enabled browser. In order to place arbitrary research
`
`information about the MBNMS in a geographic context, a user needs to be able to relate
`
`MBNMS data with the location the data describes or pertains to in the sanctuary. By
`
`constructing the model in VRML, a background of the appropriate geographic location
`
`can be added in a manner analogous to adding a background texture to a 2D HTML page.
`
`VRML can be geo-referenced with a cartographic coordinated system to support the
`
`13
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`40
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`

`
`addition of the terrain to a scene. The goal of this thesis is the development of a VRML-
`
`based model of the MBNMS that is accessible over the Web which can enable a user to
`
`select a portion of Monterey Bay National Marine Sanctuary (MBNMS) terrain and
`
`easily add scientific content or data to the selected scenery. Thus, the end product will
`
`allow the user to place 3D content in a geographic MBNMS context. Of primary concern
`
`when attempting to construct such a model is the methodology by which low-resolution
`
`3D scenery is exchanged for higher resolution scenery, all the while maintaining the
`
`overarching context of the MBNMS environment with the content added. Because
`
`bathymetric data of the MBNMS seafloor is available and that