stereo-oxford

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1、StereoReconstructionShape(3D)fromtwo(ormore)imagesknowncameraviewpointsExampleimagesshapesurfacereflectanceScenariosThetwoimagescanarisefrom•Astereorigconsistingoftwocameras•thetwoimagesareacquiredsimultaneouslyor•Asinglemovingcamera(staticscene)•thetwoim

2、agesareacquiredsequentiallyThetwoscenariosaregeometricallyequivalentStereoheadCameraonamobilevehicleTheobjectiveGiventwoimagesofasceneacquiredbyknowncamerascomputethe3Dpositionofthescene(structurerecovery)Basicprinciple:triangulatefromcorrespondingimagepo

3、ints•Determine3Dpointatintersectionoftwoback-projectedraysCorrespondingpointsareimagesofthesamescenepointTriangulation/CCTheback-projectedpointsgeneraterayswhichintersectatthe3DscenepointAnalgorithmforstereoreconstruction1.Foreachpointinthefirstimagedeter

4、minethecorrespondingpointinthesecondimage(thisisasearchproblem)2.Foreachpairofmatchedpointsdeterminethe3Dpointbytriangulation(thisisanestimationproblem)ThecorrespondenceproblemGivenapointxinoneimagefindthecorrespondingpointintheotherimageThisappearstobea2

5、Dsearchproblem,butitisreducedtoa1DsearchbytheepipolarconstraintOutline1.Epipolargeometry•thegeometryoftwocameras•reducesthecorrespondenceproblemtoalinesearch2.Stereocorrespondencealgorithms3.TriangulationNotation/ThetwocamerasarePandP,anda3DpointXisimaged

6、asXPP/P:3×4matrixxx/X:4-vectorx:3-vector/CCWarningforequationsinvolvinghomogeneousquantities‘=’means‘equaluptoscale’EpipolargeometryEpipolargeometryGivenanimagepointinoneview,whereisthecorrespondingpointintheotherview??epipolarlineCC/epipolebaseline•Apoin

7、tinoneview“generates”anepipolarlineintheotherview•ThecorrespondingpointliesonthislineEpipolarlineEpipolarconstraint•Reducescorrespondenceproblemto1DsearchalonganepipolarlineEpipolargeometrycontinuedEpipolargeometryisaconsequenceofthecoplanarityofthecamera

8、centresandscenepointXxx//CCThecameracentres,correspondingpointsandscenepointlieinasingleplane,knownastheepipolarplaneNomenclatureX/rightepipolarlinelleftepipolarlinexx/e/e/CC/•Theepipolarlinelistheimageoftheraythrou