Reconstructing Camera Positions from Visibility Informa

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1、ReconstructingCameraPositionsfromVisibilityInformationElifTosunHonorsThesisPresentationAdvisor:IleanaStreinuMay1st,2002OutlineMotivationGeneralProblemSomeDefinitionsMainProblemsofInterestBackgroundinRigiditySolutionsin2DFurtherWorkSummaryMotivation:MITCityScanningProj

2、ectGoal:Toreconstructa3Dmodelofanurbanenvironmentusingnumerousimages.Method:RobotwithamountedhemisphericalcameraImagesacquiredatdifferent*unknown*positionsofanurbanenvironmentImagesputtogethertoget“imagefeaturepoints”usingmethodsinComputerVisionandComputerGraphics.Motiv

3、ation:MITCityProjectAcornermaybeanimagefeaturepointMethod(Cont’d):Slopesbetweencamerasandimagefeaturesareinferredfromuseofhemisphericalcameraswithknownlocalorientations.Oncethesetofslopesareobtained,solutionforcameraandimagefeaturepositionsisbasedonsolvingalinearsystemo

4、fequationsHowever…Alinearsystemofequationsmaybeoverorunderdetermined.ThisinformationisNOTknownaprioriTherefore,system*sometimes*mayfailtogiveasolution.ASUBSETofedgesthatgiveauniquesolutionisneeded.“…determinationoftheminimalsetofdistinctpairsneededforanon-degeneratesolu

5、tionissignificantlymorecomplicatedanddependsentirelyonthetopologyoftheadjacencygraph.”[Antone-Teller,2000]TheProblemGiven:VisibilityinformationasasetofslopesatnpositionsofahemisphericalcameraFind:AbsolutecoordinatesofcameralocationsandpositionsofimagefeaturesWhy?Maybeus

6、edtoreconstructamodelofenvironment.Problem?Over-orunder-determinedsystemofequations.Needasubset.Thisthesisfocuseson:Reformulatingthisproblemandmodelingitbasedonitsgeometric/combinatorialaspectsExploringitin2and3dimensionsIsolatingseveralfeasiblesubproblemsandgivingalgor

7、ithmicsolutionsProvidingimplementationsforsomeGeneralCameraRegistrationProblemFormulationusing“directionnetworks”Dataset:3cameras,4imagefeaturepoints,slopeknownfor13pairsDirectionNetwork:7(=3+4)vertices13edgesDirectionNetwork?AdirectionnetworkisagraphG=(V,E)togetherwith

8、slopeinformationforeachedge:D=(V,E,S)withS={se:seistheslopeinformationforanedgeeE}GeneralCameraRegistrationPr