数字地形模型 (4)

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1、Contents3.1DatasourcesfordigitalterrainmodellingDigitalTerrainModelling3.2Photogrammetry3.3RadargrammetryandSARInterferometry3.4Airbornelaserscanning(Lidar)Chapter3TechniquesforAcquisitionof3.5CartographicdigitisationDTMSourceData3.6GPSfordirectdataacquisitio

2、n3.7ThecomparisonbetweenDTMdatafromdifferentsources3.1DatasourcesfordigitalterrainmodellingDifferenttechniquesfordifferentsourcesDatasourcesmeansthematerialsfromwhichdata¾FieldsurveyingbyusingtotalstationtheodoliteandcanbeacquiredforterrainmodellingandbyDTMGP

3、S(globalpositioningsystems)fordirectsourcedatameansdataacquiredfromdatasourcesofmeasurementfromterrainsurfacesdigitalterrainmodelling.¾Cartographicdigitizationbyusingexistingtopographicmapsanddigitisers¾Photogrammetrybyusingstereo-pairsofaerial(orspace)images

4、andphotogrammetricinstruments¾Laserscanning:activelyprovidingitsownilluminationintheformoflasers¾SAR:radargrammetry,interferometryandradarclinometry,activelyprovidingitsownilluminationintheformofmicrowaves1FromterrainsurfaceFromaerialandspaceimages¾Thecontine

5、ntsoccupy29.2%oftheearth’ssurface.¾AerialimagesarethemosteffectivewaytoproduceReliefvariesfromplacetoplace,andiscoveredbyandupdatetopographicmapsnaturalandculturalfeatures,apartfromwaterVthemostvaluabledatasourceforlarge-scale¾Differentmeasurementtechniquesma

6、ybeusedproductionofhigh-qualityDTMbecausesometechniquesmaybelesssuitableforVtakenbymetriccamerasmountedonaerialplanessomeareasTypesofaerialphotographsFromaerialandspaceimagesbasedonangularfieldofviewAerialphotographscanbeclassifiedintodifferenttypesbasedondif

7、ferentcriteria:VBasedoncolour:colour(trueorfalse)andmonochromaticphotographsVBasedontheattitudeofphotography:vertical(i.e.mainopticalaxisvertical),tilted(≤3°),andoblique(>3°)photographs.CommonlyusedaerialphotographsaretiltedphotographVBasedonangularfieldofvie

8、w:normal,wideangleandsuperwideanglephotography2Aerialcameraandaerialphotography¾FormAerialphoto(negative)Vinanalogueform–recordedonfilms;andfPerspectivecentre(lens)Vindigitalform–scanned/