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  • 1. Workshop 3D standaarden 24 Juni 2010
  • 2. Diversen…
    • 3D:
      • BReps (Semantisch niveau)
      • Normaal vectoren
      • CSG / Boolean opp.
      • Primitieven
    • Standaarden:
      • DXF
      • SHP
      • VRML
      • X3D
      • KML / KMZ
      • Collada
      • WebGL
      • O3D
      • CityGML
      • IFC
  • 3. 3D algemeen - BRep
  • 4. 3D algemeen – Extruded Solid
  • 5. 3D algemeen - Cube
  • 6. 3D algemeen – Normaal Vectoren
  • 7. 3D algemeen – CSG (Boolean Oper.)
  • 8. 3D algemeen - Primitieven
  • 9. 3D Standaarden
  • 10. Industrial standards: DXF
    • DXF ( Drawing Interchange Format) created by Autodesk, December 1982 as part of AutoCAD 1.0
    • Support many different geometries, layers and drawing attributes
    • Does not support thematic attributes
    • Specifications for DXF from AutoCAD Release 13 (November 1994) to AutoCAD 2008 (March 2007) on the web site
    http://www.autodesk.com/techpubs/autocad/acad2000/dxf/index.htm
  • 11. Industrial standards: ESRI SHP
    • Created by the Environmental System Research Institute (ESRI).
    • point, multi-point, polygon, polyline and multi-patches.
    • SHP adapted for faster drawing speed and editing capabilities.
    • Contains thematic attributes
    • Consists of three files:
    • Main file: *.shp Index file: *.shx DBase file: *.dbf
    http://esri.com/library/whitepapers/pdfs/shapefile.pdf
  • 12. Disadvantages
    • Need to be accepted by other vendors
    • Vendors provide new versions
    • Not for visualisation on Internet
  • 13. Virtual Reality Modelling Language (VRML)
    • Started in 1995, 1997 accepted as a standard
    • Web standard for exchange of graphics
    • Language for modelling 3D realistic scenes and interaction
    • ASCII file format
  • 14. VRML basics
    • Nodes for all
    • scene components:
    • 3D Geometry
    • Lights
    • Shading
    • Colours
    • Texture (draping and mapping)
    • camera
    • + behaviour
  • 15. VRML many possibilities to design a scene (e.g. nodes )
    • http://www.web3d.org/technicalinfo/specifications/vrml97/part1/nodesRef.html
    • 3D Geometry – points, extruded shapes
    • Lights – background, point, directional lights
    • Shading – normal vectors
    • Texture – draping
    • View – several view points
    • Fog, billboard
    • Grouping nodes – group
    • Transform – rotate, scale, translate
    • Inline – link to another node
    • Sensors – to sense user actions
    • Routes – to pass the action to another node
    • Scripts – Java, Javascript
  • 16. VRML creating and editing the file (VR modellers)
  • 17. VRML: mostly used for visualisation
    • Good visualisation results in large files (gzip)
    • Simple visualisation is ‘too schematic’
    • Inventor – file format (not XML)
    • Thematic (semantic info) cannot be stored
  • 18. X3D
    • Web3D Consortium
    • Based on XML and Open Inventor
    • More possibilities for visualization and interaction
    • Extensions for various purposes: X3D Core, X3D Interchange, X3D CAD, X3D Geospatial and X3D Immersive
    • Browser makers can define their own extensions and submit them for standardisation by the Web3D Consortium .
    http://www.web3d.org/x3d/specifications/x3d/
  • 19. X3D
    • Few browsers
    • No export from CAD and GIS vendors (developing own web applications)
    • No standardised thematic information (semantics)
  • 20.  
  • 21. Keyhole Markup Language (KML)
      • Developed by the company Keyhole (bought by Google) Google brought KML into OGC
      • Goals according to the specification document:
      • Language for presentation of geographic features and annotations (geographic coordinates)
      • Web-based online maps (2D) and digital globes (3D).
      • Focus on visualization and user interaction
      • No semantics
  • 22. KML
      • KML supports
        • georeferenced images and 2D and 3D shapes in different styling options
        • definition of pictograms and textual markers
        • association of HTML and other content with the shapes
        • geographic embedding of 3D computer graphics models (e.g. COLLADA, X3D)
      • KML is not based on ISO 191xx standards
  • 23.  
  • 24. COLLADA
      • COLLA borative D esign A ctivity: Open Standard, KHRONOS Group
      • generic, extensible format for 3D digital contents creation
      • design background: computer graphics and gaming
      • good representation of 3D geometry and appearance (since V1.4 supported of topology)
      • strong appearance and physics models (shaders, animation, ragdolls)
      • no explicit support of semantics and (up to V1.4) no georeferencing
      • Beheerd door Kronos groep
  • 25. WebGL
    • 3D Web standaard
    • Javascript implementatie
      • Géén plugin nodig
      • Hardware acceleratie via grafische kaart
    • Binding voor JS om OpenGL ES aan te roepen
    • Net als Collada: Kronos groep
  • 26. O3D
    • Van Google
    • Binaire representatie
    • Browserplugin nodig
    • Gestart omdat WebGL JavaScript gebaseerd is
    • Gestopt omdat dat toch goed bleek….
  • 27.  
  • 28.  
  • 29. CityGML
    • Content / Entities:
    • Digital Terrain Model / Relief
    • Land Use
    • GenericCityObject
    • Sites
      • Buildings
      • Bridges
      • Tunnels
      • Walls
      • Landfills
      • Excavations
    • Transportation objects
      • Streets
      • Railways
    • Water bodies
    • Vegetation objects
    • City furniture
      • e.g. street lights, traffic lights, benches
  • 30. Important features
    • Semantics
    • Object parts are modeled as features
      • can be assigned thematic attributes
    • Geometric-topological model
    • Recursive aggregation of objects and geometries
    • Textured surfaces
    • Subsurface objects
      • tunnels, pedestrian underpasses
    • Generic concept for external references
      • every object can have a link to external resources
    • Multi-scale model: five levels of detail (LoD 0-4)
  • 31. CityGML: semantic and geometric model Courtesy T. Kolbe
  • 32. Semantics and geometry
    • KML
    • Multipatch
    • CityGML
  • 33. Semantics and geometry
    • No defininitions of the objects
    • Very general attrtibutes (type, use, ...)
    • Until recently only undeground
      • Cables and pipes
      • Tunnels
    • Geometries as in GML (or DBMS if data model)
    • One object (feature) may have several geometric representations
  • 34. Topology/Validity
    • Rules are recommended
    • Validity is not checked
    • No specific topological data structure
    • (in the GML version)
  • 35. Important concept: Levels of Detail LOD 4 (Walkable) LOD 1 (Block-roof) LOD 2 (Block+roof) LOD 3 (Architectural envelope)
  • 36. Example: Building in CityGML
    • <Building gml:id=“Building0815&quot;> ..................
    • <lod2SolidProperty>
    • <gml:Solid srsName=&quot;urn:adv:crs:ETRS89_3GK2-h&quot;>
    • <gml:exterior>
    • <gml:CompositeSurface>
    • <gml:surfaceMember>
    • <gml:OrientableSurface orientation=&quot;+&quot;>
    • <gml:baseSurface>
    • <gml:Polygon>
    • <gml:exterior>
    • <gml:LinearRing>
    • <gml:pos >1.0 1.0 0.0</gml:pos>
    • <gml:pos >3.0 1.0 0.0</gml:pos>
    • ..........................
    • </gml:LinearRing>
    • .....................
    • < /lo d2SolidProperty>
    • < / Building>
    Courtesy T. Kolbe
  • 37.  
  • 38. IFC
    • Semantic, topology, geometry, attributes and relations
    • Geometry:
      • CSG / Boolean operations
      • Solids
      • Semantic Geometry!
  • 39. Hoe ziet het eruit? www.ifcbrowser.com
  • 40.  
  • 41. IFG
    • Afspraak over semantische uitbreiding van IFC
    • Voor Georeferentie
    • Weinig toegepast in de praktijk
  • 42. Conclusie
  • 43. 3D standaarden conclusie
    • Veel standaarden voor representatie
    • CityGML en IFC hebben semantiek als meerwaarde!!
    • Uitwisseling van data versus uitwisseling van 3D