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1、第六章引言(Introduction)Example1:pp2~3INTRODUCTIONThetexturedurbanenvironmentattractstomanyapplications,e.g.,tourism,entertainment,iirchitectureandtownplanning,cityclimate,noisepropagation,environmentalresearch,etc.,becauseofitshighvisualrealism,wellprese
2、ntationofculturalandfunctionalinformationoftheurbansite.Duetoquitelowautomation,however,theoperationofretrievaloftexturefromvariousimagesourcetogeneratearealbuilding3Dmodelhasstillbeenlabor-intensive,tediousandturnouttobeoneofbiggestobstaclesforphoto
3、-realistic3DVisualizationofurbanenvironmentalthoughsignificanteffortsforincreasingtheautomationashighaspossiblehavebeenpursuedbymanyresearchersintherecentyears[1,2,3,5,7,8]Methodsforbuildingtextureretrievalmentionedintheliteraturecanbegenerallygroupe
4、dthreeclasses:(1)texturingbuildingtopsusingtop-downviewsoftheroofs,typically,airborneaerialimages[4],(2)texturingfacadesbyutilizingground-basedimages[2,6,9],and(3)theircombination[10].Eachofthemhasitsadvantagesanddisadvantages.Whiletop-downaerialimag
5、eiscapableofefficientlyprovidingacompletesetoftheroofshapesofallbuildingsatsufficientdetailandaccuracy,theverticalwallsofbuildingsareusuallyinvisibleinnormalhorizontalaerialimage・Whileground-baseddataacquisitionsystemsarecapableofprovidingbuildingfac
6、adesasseenfromthestreetlevel[5,11],itwilltakeseveralmonthsforseveralfull-timeemployeestoextractthefacadestructuresfromtheseimages,Moreover,theroofsofbuildingarenotaccessiblefromtheground-basedacquisitionsystemifthebuildingistoohigh.Toensureallsidesof
7、buildingfacadesinacityareaarccovered,moreandmoreresearchersarecombiningtheairborne-andground-basedsourcestocompensateforonesingletop-downaerialimagesourcesorterrestrialimagessourcesforhigh-qualityfacadetextures.However,thecombinationoftwodatasourcesr
8、equirestwodataacquisitionplatform,whichincreasethecostoftexturedataacquisition,andthepost-processingalgorithmsalsorequirestwotypesofprocessingprogram:onefortop-downimages,andtheotheroneisforground-basedimages.Therefore,thelabor-intensionhasnotinfacts
