Practical Shadow Mapping

《Practical Shadow Mapping》由会员上传分享，免费在线阅读，更多相关内容在学术论文-天天文库。

1、PracticalShadowMappingStefanBrabecThomasAnnenHans-PeterSeidelMax-Planck-InstitutfurInformatik¨Saarbrucken,Germany¨AbstractInthispaperweproposeseveralmethodsthatcangreatlyimproveimagequalitywhenusingtheshadowmappingalgorithm.Shadowartifactsintroducedbyshadowmappingaremainlydue

2、tolowresolutionshadowmapsand/orthelimitednumericalprecisionusedwhenperformingtheshadowtest.Theseproblemsespeciallyarisewhenthelightsource’sviewingfrustum,fromwhichtheshadowmapisgenerated,isnotadjustedtotheactualcameraview.Weshowhowatightfittingfrustumcanbecomputedsuchthatthesh

3、adowmappingalgorithmconcentratesonthevisiblepartsofthesceneandtakesadvantageofnearlythefullavailableprecision.Furthermore,werecommenduniformlyspaceddepthvaluesincontrasttoperspectivelyspaceddepthsinordertoequallysamplethesceneseenfromthelightsource.1.IntroductionShadowmapping

4、[10,7]isoneofthemostcommonshadowtechniquesusedforrealtimerendering.Inrecentyears,dedicatedhardwaresupportforshadowmapping(highprecisiondepthtextures,shadowtestfunctionality)madeitswayfromhigh-endvisualizationsystemstoconsumerclassgraphicshardware.Inordertoobtainvisuallypleasi

5、ngshadowsonehastobecarefulaboutsamplingartifactsthatarelikelytooccur.Theseartifactsespeciallyarisewhenthelightsource’sviewingfrustumisnotadaptedtothecurrentcameraview.Recently,twopapersaddressedthisissue.Fernandoetal.[2]cameupwithamethodcalledAdaptiveShadowMaps(ASMs)wherethey

6、proposedahierarchicalrefinementstructurethatadaptivelygeneratesshadowmapsbasedonthecameraview.ASMscanbeusedforhardware-acceleratedrenderingbutrequiremanyrenderingpassesinordertorefinetheshadowmap.Stammingeretal.[8]showedthatitisalsopossibletocomputeshadowmapsinthepost-perspecti

7、vespace(normalizeddevicecoordinates)ofthecurrentcameraview.ThesePerspectiveShadowMaps(PSMs)canbedirectlyimplementedinhardwareandgreatlyreduceshadowmapaliasing.Inthispaperwefocusonthetraditionalshadowmapalgorithmandshowhowthelightsource’sviewingfrustumcanbeadjustedtousemostoft

8、heavailableprecision,intermsofshadowmapresolution.Sinceitisalsoimpor