the early history of point-based graphics

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1、Theearlyhistoryofpoint-basedgraphicsMarcLevoyStanfordUniversityWhyisitworthwhiletostudywhereanideacamefrom?ThomasKuhn,writinginTheStructureofScientificRevolu-tions,notesthatscientistsliketoseetheirdisciplinespast"developinglinearlytowarditspresentvantage."Asaresult,te

2、xt-booksoftendiscardorobscuretheoriginsofideas,therebyrobbingstudentsoftheexperienceofascientificrevolution.Thisinturnmakesthemunabletorealizewhenoneisuponthem,andignorantabouthowtoactinthesecircumstances.Idonotclaimthatpoint-basedrenderingwasascientificrevolution,atle

3、astnotin1985whenTurnerWhittedandIwroteourfirstpaperonthetopic.However,thatpaperwaswritteninresponsetoascientificcrisis,whichbearssomeofthesamecharacter-istics.Asatechnicalachievement,ourpaperwasafailure.However,asastoryofcrisisandresponseitisinstructive.InthisspiritIof

4、ferthefollowinghistoricalaccount.Sample-basedrepresentationsofgeometrySincethebeginningofcomputergraphics,acreativetensionhasexistedbetweenrepresentingscenesasgeometryversusascollectionsofsamples.Earlysample-basedrepresentationsincludedtextures,sprites,rangeimages,an

5、ddensityvolumes.Morerecentexamplesincludelightfields,layereddepthimages,imagecaches,andsoon.Pointsareanothersuchrepresen-tation,oftenusedtoapproximatecurvedsurfacesasthisbookamplydemonstrates.Ineachcaseresearchersfacedacommonsetofchallenges:howtoeditthescenebymanipula

6、tingitssamples,howtostoreandcompressthesesamples,howtotrans-formandshadethem,andhowtorenderthemwithcorrectsampling,visibility,andfiltering.However,tounderstandtheearlyhistoryofpointrendering,wemustunderstandadifferenttensionthatexistedintheearlyhistoryofcomputergraphi

7、cs-betweenimage-orderandobject-orderalgorithmsfordisplayinggeometricprimitives.ItwasinresponsetothistensionthatTurnerWhittedandIproposedpointsasawaytodisplaycurvedsurfaces[1985].Anditwasontheshoalsofsampling,visibility,andfilteringthatouridearanaground.Letusseewhy.Ima

8、ge-orderversusobject-ordervisibilityandantialiasingInhisseminalpaperonhidden-surfacealgorithms,IvanSutherland[1974]showedthatvisibi