Material Appearance Modeling: A Data-Coherent Approach

184 Pages·2013·7.87 MB·English

by  Yue Dong

Yue Dong
Stephen Lin
Baining Guo
Material Appearance
Modeling:
A Data-Coherent
Approach
Material Appearance Modeling: A Data-Coherent
Approach
Yue Dong (cid:2) Stephen Lin (cid:2) Baining Guo
Material Appearance
Modeling:
A Data-Coherent
Approach
YueDong
StephenLin
BainingGuo
MicrosoftResearchAsia
Beijing,China
ISBN978-3-642-35776-3 ISBN978-3-642-35777-0(eBook)
DOI10.1007/978-3-642-35777-0
SpringerHeidelbergNewYorkDordrechtLondon
LibraryofCongressControlNumber:2013938953
ACMComputingClassification(1998): I.3
©Springer-VerlagBerlinHeidelberg2013
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Preface
One of the most prominent goals of computer graphics is to generate images that
look as real as photographs. Realistic computer graphics imagery has however
proventobequitechallengingtoproduce,sincetheappearanceofmaterialsarises
fromcomplicatedphysicalprocessesthataredifficulttoanalyticallymodelandsim-
ulate,and image-basedmodelingof real materialsamplesis oftenimpracticaldue
tothehigh-dimensionalspaceofappearancedatathatneedstobeacquired.
This book presents a general framework based on the inherent coherency in
the appearance data of materials to make image-based appearance modeling more
tractable.Weobservethatthiscoherencemanifestsitselfaslow-dimensionalstruc-
ture in the appearance data, and by identifying this structure we can take advan-
tageofittosimplifythemajorprocessesintheappearancemodelingpipeline.This
frameworkconsistsoftwokeycomponents,namelythecoherencestructureandthe
accompanyingreconstructionmethodtofullyrecoverthelow-dimensionalappear-
ance data from sparse measurements. Our investigation of appearance coherency
hasledtothreemajorformsoflow-dimensionalcoherencestructureandthreetypes
ofcoherency-basedreconstructionuponwhichourframeworkisbuilt.
This coherence-based approach can be comprehensively applied to all the ma-
jor elements of image-based appearance modeling, from data acquisition of real
material samples to user-assisted modeling from a photograph, from synthesis of
volumestoeditingofmaterialproperties,andfromefficientrenderingalgorithmsto
physicalfabricationofobjects.Inthisbookwepresentseveraltechniquesbuilton
thiscoherencyframeworktohandlevariousappearancemodelingtasksbothforsur-
facereflectionsandsubsurfacescattering,thetwoprimaryphysicalcomponentsthat
generatematerialappearance.Webelievethatcoherency-basedappearancemodel-
ingwillmakeiteasierandmorefeasibleforpractitionerstobringcomputergraphics
imagerytolife.
Beijing,China YueDong
StephenLin
BainingGuo
v
Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1.1 FundamentalsofLightInteractionwithMaterials . . . . . 3
1.1.2 TaxonomyofLightScatteringFunctions . . . . . . . . . . 5
1.1.3 ModelingandRenderingPipelineofMaterialAppearance . 8
1.2 DataCoherenceforAppearanceModeling . . . . . . . . . . . . . 9
1.2.1 DataCoherence . . . . . . . . . . . . . . . . . . . . . . . 9
1.2.2 Coherence-BasedReconstruction . . . . . . . . . . . . . . 12
1.2.3 AGeneralFrameworkforCoherence-BasedAppearance
Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.3 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.3.1 AcquisitionandModelingofOpaqueSurfaces . . . . . . . 14
1.3.2 ModelingandRenderingofSubsurfaceLightTransport . . 15
1.3.3 MaterialFabrication . . . . . . . . . . . . . . . . . . . . . 16
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
PartI AcquisitionandModelingofOpaqueSurfaces
2 SurfaceReflectanceOverview . . . . . . . . . . . . . . . . . . . . . . 21
2.1 SurfaceReflectanceAcquisition . . . . . . . . . . . . . . . . . . . 21
2.1.1 DirectMeasurement . . . . . . . . . . . . . . . . . . . . . 21
2.1.2 AngularCoherence . . . . . . . . . . . . . . . . . . . . . 22
2.1.3 SpatialCoherence . . . . . . . . . . . . . . . . . . . . . . 23
2.2 InteractiveModelingandEditing . . . . . . . . . . . . . . . . . . 24
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3 EfficientSVBRDFAcquisitionwithManifoldBootstrapping . . . . . 27
3.1 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2 SVBRDFManifoldBootstrapping . . . . . . . . . . . . . . . . . 30
3.2.1 RepresentativeandKeyMeasurement. . . . . . . . . . . . 30
3.2.2 ManifoldBootstrappingOverview . . . . . . . . . . . . . 31
3.2.3 ManifoldBootstrappingDetails . . . . . . . . . . . . . . . 33
vii
viii Contents
3.2.4 SyntheticEnlargementforRepresentatives . . . . . . . . . 34
3.2.5 KeyMeasurementValidation . . . . . . . . . . . . . . . . 35
3.3 SVBRDFDataAcquisition . . . . . . . . . . . . . . . . . . . . . 36
3.3.1 AcquiringRepresentatives:BRDFSamples . . . . . . . . . 36
3.3.2 AcquiringKeys:ReflectanceMaps . . . . . . . . . . . . . 38
3.4 ExperimentalResults . . . . . . . . . . . . . . . . . . . . . . . . 40
3.4.1 MethodValidation . . . . . . . . . . . . . . . . . . . . . . 41
3.4.2 SVBRDFCaptureResults . . . . . . . . . . . . . . . . . . 42
3.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4 InteractiveSVBRDFModelingfromaSingleImage . . . . . . . . . 49
4.1 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.2 SystemOverview . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.3 User-AssistedShadingSeparation . . . . . . . . . . . . . . . . . . 54
4.3.1 SeparationasOptimization . . . . . . . . . . . . . . . . . 55
4.3.2 InteractiveRefinement . . . . . . . . . . . . . . . . . . . . 56
4.3.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.4 Two-ScaleNormalReconstruction . . . . . . . . . . . . . . . . . 59
4.5 User-AssistedSpecularAssignment . . . . . . . . . . . . . . . . . 62
4.6 ExperimentalResults . . . . . . . . . . . . . . . . . . . . . . . . 64
4.7 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
PartII ModelingandRenderingofSubsurfaceLightTransport
5 OverviewofSubsurfaceLightTransport . . . . . . . . . . . . . . . . 75
5.1 ComputingSubsurfaceLightTransport . . . . . . . . . . . . . . . 75
5.2 CapturingSubsurfaceScatteringEffects . . . . . . . . . . . . . . 76
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
6 ModelingSubsurfaceLightTransportwiththeKernelNyström
Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
6.1 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
6.2 TheKernelNyströmMethod . . . . . . . . . . . . . . . . . . . . 82
6.2.1 KernelExtension. . . . . . . . . . . . . . . . . . . . . . . 83
6.2.2 EstimatingtheLightTransportKernelf . . . . . . . . . . 84
6.3 AdaptiveLightTransportMeasurement . . . . . . . . . . . . . . . 85
6.4 ResultsandDiscussions . . . . . . . . . . . . . . . . . . . . . . . 87
6.4.1 MethodValidation . . . . . . . . . . . . . . . . . . . . . . 88
6.4.2 SubsurfaceScatteringResults . . . . . . . . . . . . . . . . 92
6.4.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 92
6.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
7 ModelingandRenderingSubsurfaceScatteringUsingDiffusion
Equations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7.1 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Contents ix
7.2 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
7.3 AcquisitionofMaterialModel. . . . . . . . . . . . . . . . . . . . 100
7.3.1 DataCapture . . . . . . . . . . . . . . . . . . . . . . . . . 100
7.3.2 VolumetricModelAcquisition . . . . . . . . . . . . . . . 102
7.3.3 AdjointMethodforGradientComputation . . . . . . . . . 103
7.3.4 GPU-BasedDiffusionComputation . . . . . . . . . . . . . 104
7.3.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 104
7.4 RenderingandEditing . . . . . . . . . . . . . . . . . . . . . . . . 105
7.4.1 PolygridConstruction . . . . . . . . . . . . . . . . . . . . 106
7.4.2 GPU-BasedPolygridDiffusionComputation . . . . . . . . 108
7.4.3 HierarchicalAcceleration . . . . . . . . . . . . . . . . . . 111
7.4.4 Editing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
7.5 ExperimentalResults . . . . . . . . . . . . . . . . . . . . . . . . 113
7.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
8 ModelingTexturedTranslucentMaterialswithLazySolidTexture
Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
8.1 PreviousWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
8.2 OverviewandTerminology . . . . . . . . . . . . . . . . . . . . . 124
8.3 3DCandidatesSelection . . . . . . . . . . . . . . . . . . . . . . . 125
8.3.1 ColorConsistency . . . . . . . . . . . . . . . . . . . . . . 126
8.3.2 TriplesofCoherentCandidates . . . . . . . . . . . . . . . 127
8.3.3 CandidateSlab . . . . . . . . . . . . . . . . . . . . . . . . 128
8.4 LazySolidSynthesis . . . . . . . . . . . . . . . . . . . . . . . . . 129
8.4.1 ParallelSolidTextureSynthesis . . . . . . . . . . . . . . . 129
8.4.2 LazySubsetSynthesis . . . . . . . . . . . . . . . . . . . . 132
8.5 ImplementationandResults . . . . . . . . . . . . . . . . . . . . . 133
8.5.1 CandidatePre-computation . . . . . . . . . . . . . . . . . 133
8.5.2 GPUImplementation . . . . . . . . . . . . . . . . . . . . 134
8.5.3 Rendering . . . . . . . . . . . . . . . . . . . . . . . . . . 135
8.5.4 FullVolumeSynthesisandComparisons . . . . . . . . . . 135
8.5.5 SolidSynthesisforTranslucentObjects . . . . . . . . . . . 136
8.6 DiscussionandConclusions . . . . . . . . . . . . . . . . . . . . . 138
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
PartIII MaterialFabrication
9 OverviewofMaterialFabrication . . . . . . . . . . . . . . . . . . . . 143
9.1 Hardware . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
9.1.1 BasicConsiderations . . . . . . . . . . . . . . . . . . . . 143
9.1.2 MillingMachine . . . . . . . . . . . . . . . . . . . . . . . 144
9.1.3 3DPrinter . . . . . . . . . . . . . . . . . . . . . . . . . . 145
9.1.4 ConventionalPrinter . . . . . . . . . . . . . . . . . . . . . 146
9.2 MaterialFabrication . . . . . . . . . . . . . . . . . . . . . . . . . 147
9.2.1 DiffuseShading . . . . . . . . . . . . . . . . . . . . . . . 147
x Contents
9.2.2 SurfaceReflectance . . . . . . . . . . . . . . . . . . . . . 149
9.2.3 SubsurfaceScattering . . . . . . . . . . . . . . . . . . . . 150
9.2.4 DeformationBehavior . . . . . . . . . . . . . . . . . . . . 150
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
10 FabricatingSpatially-VaryingSubsurfaceScattering . . . . . . . . . 153
10.1 RelatedWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
10.2 SystemPipeline . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
10.3 MaterialMapping . . . . . . . . . . . . . . . . . . . . . . . . . . 160
10.3.1 HomogeneousBSSRDFs . . . . . . . . . . . . . . . . . . 160
10.3.2 HeterogeneousBSSRDFs . . . . . . . . . . . . . . . . . . 161
10.4 HardwareManufacturingSetup . . . . . . . . . . . . . . . . . . . 165
10.5 ExperimentalResults . . . . . . . . . . . . . . . . . . . . . . . . 166
10.6 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
11 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
11.1 FutureWork . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Erratum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E1
Chapter 1
Introduction
Ithaslongbeenagoalofcomputergraphicstosynthesizeimageryindistinguishable
inappearancefromtherealworld.Withhighrealismincomputergraphics,created
objectsandscenescancometolife,providingviewerswithcompellingvisualexpe-
riencesinavarietyofmedia,includingsimulators,moviesandvideogames.Ahigh
level of realism however has been challenging to achieve, due to complex factors
thatdeterminetheappearanceofobjectsandscenes.
In images, the appearance of an object is formed from two components. One
isshape,forwhichthereexistsvariousmethodsforaccurate3Dmeasurement,in-
cludingsystemssuchasstereocamerasandlaserscanners.Theotherisreflectance,
whichdescribesthewayanobject’smaterialsappearunderdifferentviewingandil-
luminationconditions.Differentmaterialscanhavevastlydifferentreflectanceprop-
erties,dependingonhowtheyinteractwithlight.Somematerials,suchaswax,are
characterized by light penetration and extensive scattering within their volumes,
which leads to a soft and smooth appearance from the emergent radiance. Others
such as polished metals have a relatively hard appearance because of highly di-
rectionalmirror-likereflectionsoflightoffthematerialsurface.Yetothersexhibit
different visual effects, such as the retro-reflection of street signs where the illu-
mination of car headlights is largely reflected back in the direction from which it
came,or thetransparencyof applejuice, throughwhichlightpasses withlittlein-
teractionatall.Reflectanceisthesourceofamaterial’sintrinsicvisualappearance,
andmodelingofthisphenomenaisthefocusofthisbook.
For realistic modeling of appearance, detailed reflectance data is essential, as
illustrated in Fig. 1.1. Often only slight differences in reflectance distinguish the
appearance of one material from another, so even subtle reflectance features need
tobeaccountedfor,anddonesowithhighaccuracy,tomakeamateriallookcon-
vincing. The reflectance of a material encompasses not only the appearance of a
singlepoint,butalsothespatialvariationsoverthesurfaceandwithinthematerial
volume.Thesespatialvariationsmaysimplybechangesincolor,suchasonamag-
azine cover, or they may include complete changes in optical properties, such as
glitterinnailpolish.Theneedforhighlydetailedappearancemodelshasbeenmag-
nified by recent increases in image display resolution, from VGA to XVGA, and
Y.Dongetal.,MaterialAppearanceModeling:AData-CoherentApproach, 1
DOI10.1007/978-3-642-35777-0_1,©Springer-VerlagBerlinHeidelberg2013