第八章三维电子地图

†††††††††8.1VR†††8.1.1†††††Wedefineatopographic3D-mapasacartographicrepresentationofalandscapesectioninaperspectiveviewcombinedwithtopographicinformationthatisdefinedinalegend.†8.1.2††††††8.1.3††2Atopographic3D-mapinheritssomeimportantpropertiesoftraditionaltopographicmapsaslistedbyHakeandGruenreich(1994):(1)Thegeographicalpositionofallelementsisdefinedandcanbeextractedbythereader.(2)Allmappedelementsbelongtodefinedcategories.(3)Thesecategoriesofmapelementsdifferclearlyfromeachother.†3Animportantdifferencetotraditionaltopographicalmapsisthevisualizationoftopographicalcontext.Intheorthogonalperspectiveofa2D-map,thetopographyissymbolizedbycontours,terrainpointsandshadedrelief.Inthetopographic3D-map,thetopographiccontextofamapelementisvisualizeddirectlyintheperspectiveview,aslongastheelementsarevisible.Thustheinterpretationoflandscapeformsbecomesmuchmoreintuitive.†4Athree-dimensionalinteractivetopographicmapdoesnotknowanyspatial,thematicandtemporallimitations.Itofferstheuserthepossibilitytochooseitsvirtualpositionwithinthemap,permittingamoreaccurateperceptionandinterpretationofthespatialandotherrelatedinformation.Weareconvincedthattheuseofthistechnologyinthedomainofcartographydomainwouldsignificantlyimprovethequalityofcartographicproductsandopennewareasofapplication.8.2,4:†(Tessellatingmodel)†(Vectormodel)†(Hybridmodel)†(Analyticalmodel)†celldecompositionspatialoccupancyenumeration†2.(wireframerepresentation,WFR))(boundaryrepresentation,BR)††8.3†1DEM††DEM†††SAR/INSAR†2†††††††INSAR††††††††††4††††††††††††††††73DCM,:†,,;†,,†,,,,,3DCM:„;„;,8.4†1DTMDEM„„DigitalElevationModeDEMDTM†2DEM--DEMDEM:(Grid)(TIN)†††††††4TIN††††††TINDEMTINDEM††ƒVIP,VeryImportantPointƒDH,DropHeuristic†ƒƒ8.5††1†††††2,3,3,3,32:(MBR)(IBR),3CAD„(ThreeDimensionalCityModel,3DCM)3DCMIBRMBR,3,,MBR,3,3†13BOXDEM23†††4533DMAXCADMultiGen.3ds,.dxf,.x,.dwg†5†8.6††1†††LODLODLeverofDetail†3††††4††††8.7†OpenGLOpenGraphicsLibrary:SGIOpenGLOpenGLOpenGLARBOpenGLSGIHPMicrosoftIntelIBMSUNDECAT&TUnixOpenGLWindows95/98WindowsNTMacosBeosOS/2UnixOpenGLAPI†OpenGL†1BezierNurbs†2†3RGBAColorIndex†4OpenGLRGBRGB†5†6BlendingAntialiasingFog†7DoubleBuffering†8OpenGLWindows†9,OpenGLDepthCueMotionBlur†OpenGL††††OpenGL32WindowsWindows98/NTOpenGL32.DLLGlu32.DLLOpenGL100†1115gl300†2OpenGLglu43OpenGLOpenGLOpenGL†331auxOpenGLOpenGLWindows98/NT†4WindowswglOpenGLWindows†5Win32API6†6OpenGL†††††††„ƒƒƒƒ„ƒ„ƒƒ†††RGB††††RealtimeƒLODLever-of-detaiƒDOLDynamicObjectLoadingƒCullingƒ/8.8†††††††††††††3DGIS†††1FullyImmersiveVR):Userheadsets)(data-glove)(data-suits)360VREVRE,†2Semi-ImmersiveVR):User60VRE+IMAXTheatresVRE†3Non-ImmersiveVRorDeskTop):UserjoystickVREFish-tank)†4On-LineVR):whichallowestheDistributedUsertovirtuallygettogetherandinteractwitha3DworldontheWeb.()††††††††()200227p86-88†19992†,,20023†..20008089†2001†20023†,20021†2002†AndreaTerribilini,Mapsintransition:developmentofinteractivevector-basedtopographic3D-maps,Proceedingsofthe19thInternationalCartographicConference,Ottawa,Canada:InternationalCartographicAssociation,1999,p993-1001†ChristianHaeberling,Symbolizationintopographic3D-maps:conceptualaspectsforuser-orienteddesign,Proceedingsofthe19thInternationalCartographicConference,Ottawa,Canada:InternationalCartographicAssociation,1999,p1037-1044†DirkBartz,MichaelMeiner,TobiasHüttner,OpenGL-assistedocclusioncullingforlargepolygonalmodels,Computers&Graphics,1999,23,p667-679†RickGerms,GertVanMaren,EdwardVerbree,FrederikW.Jansen,Amulti-viewVRinterfacefor3DGIS,Computers&Graphics,1999,23,p497-506†