a dual theory of inverse and forward light transport[09]

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1、ADualTheoryofInverseandForwardLightTransportJiaminBai1,ManmohanChandraker1,Tian-TsongNg2,andRaviRamamoorthi11UniversityofCalifornia,Berkeley2InstituteforInfocommResearch,SingaporeAbstract.Inverselighttransportseekstoundoglobalilluminationeects,suchasinterre ections,th

2、atpervadeimagesofmostscenes.Thispaperpresentsthetheoreticalandcomputationalfoundationsforinverselighttransportasadualofforwardrendering.Mathematically,thisdualityisestablishedthroughtheexistenceofunderlyingNeumannseriesexpansions.Physically,weshowthateachtermofourinver

3、seseriescancelsaninterre ectionbounce,justastheforwardseriesaddsthem.Whiletheconvergencepropertiesoftheforwardseriesarewell-known,weshowthattheoscillatoryconvergenceoftheinverseseriesleadstomoreinterestingconditionsonmaterialre ectance.Conceptually,theinverseproblemreq

4、uirestheinversionofalargetransportmatrix,whichisimpracticalforrealisticresolutions.Anaturalconsequenceofourtheoreticalframeworkisasuiteoffastcomputationalalgorithmsforlighttransportinversion{analogoustoniteelementradiosity,MonteCarloandwavelet-basedmethodsinforwardren

5、dering{thatrelyatmostonmatrix-vectormultiplications.Wedemonstratetwopracticalapplications,namely,separationofindividualbouncesofthelighttransportandfastprojectorradiometriccompensationtodisplayimagesfreeofglobalilluminationartifactsinreal-worldenvironments.1Introductio

6、nGlobalilluminationeectsarekeyvisualfeaturesofreal-worldscenes.Simulationoftheseeectsinforwardrenderinghasbeenextensivelystudiedincomputergraphics,withatheoreticalfoundationbasedontherenderingequation[9].Incontrast,mostcomputervisionalgorithmsareforcedtosimplyignorei

7、nterre ec-tions,whereonewouldideallyliketoinverttherenderingequationtoundotheireects.Recently,Seitzetal.[18]formalizedthisastheproblemofinverselighttransport.However,littleisknownaboutthetheoryandalgorithmsforecientlighttransportinversioninpracticalscenes.Thispaperla

8、ysthemathematicalandcomputationalfoundationsofinverselighttransport,byexposingastrongdualitytothealreadymatureframewo