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All-Frequency Rendering with Dynamic, Spatially-Varying Reflectance

All-Frequency Rendering with Dynamic, Spatially-Varying Reflectance. Jiaping Wang 1 Peiran Ren 1,3 Minmin Gong 1 John Snyder 2 Baining Guo 1,3. 1 Microsoft Research Asia 2 Microsoft Research 3 Tsinghua University. Complex, detailed reflectance.

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All-Frequency Rendering with Dynamic, Spatially-Varying Reflectance

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  1. All-Frequency Rendering with Dynamic, Spatially-Varying Reflectance Jiaping Wang1 Peiran Ren1,3 Minmin Gong1John Snyder2 Baining Guo1,3 1 Microsoft Research Asia 2 Microsoft Research 3 Tsinghua University

  2. Complex, detailed reflectance • Spatial/temporal variation • All BRDF types: • parametric ↔ measured • isotropic ↔ anisotropic • glossy ↔ mirror-like

  3. Previous work SpatialVariation SVBRDF singleBRDF TemporalVariation static dynamic

  4. Previous work SpatialVariation [Ng03][Wang04][Liu04][Wang06][Tsai06][Krivanek08] SVBRDF singleBRDF [Wang04] TemporalVariation static dynamic

  5. Previous work SpatialVariation [Green06][Green07] SVBRDF [Green06] singleBRDF [Wang04] TemporalVariation static dynamic

  6. Previous work SpatialVariation [Ben-Artzi06][Sun07][Ben-Artzi08] SVBRDF [Green06] singleBRDF [Wang04] [Ben-Artzi06] TemporalVariation static dynamic

  7. Previous work SpatialVariation • Our method: • - per-pixel SVBRDF • dynamic SVBRDF • all BRDF types- all-frequency SVBRDF [Green06] [Wang09] singleBRDF [Wang04] [Ben-Artzi06] TemporalVariation static dynamic

  8. Rendering Equation • 2D lighting • 4D visibility • 6D reflectance (SVBRDF) light visibility cosine SVBRDF n i o x

  9. Precomputed Radiance Transfer • Dot product[Sloan et al. 2002] light light transfer

  10. Precomputed Radiance Transfer • Dot product[Sloan et al. 2002] • Tripleproduct[Ng et al. 2004] light light transfer BRDF × cosine light visibility Light Transport & Precomputed

  11. Precomputed Radiance Transfer • Dot product[Sloan et al. 2002] • Tripleproduct[Ng et al. 2004] • Oursmethod light light transfer BRDF × cosine light visibility light BRDF visibility cosine LT & P LT & P

  12. Precomputed Radiance Transfer • Dot product[Sloan et al. 2002] • Tripleproduct[Ng et al. 2004] • Oursmethod light light transfer BRDF × cosine light visibility light BRDF visibility cosine LT & P LT & P LT & P

  13. Algorithm Overview o Spherical Gaussians Spherical Gaussians

  14. Algorithm Overview o Spherical Gaussians SSDF Environment

  15. Dynamic, spatial varying BRDF

  16. Outline • Reflectance Representation • Microfacet Model with SGs • Visibility Representation • Signed Spherical Distance Function • Lighting & Rendering o

  17. Outline • Reflectance Representation • Microfacet Model with SGs • Visibility Representation • Signed Spherical Distance Function • Lighting & Rendering o

  18. Spherical Gaussian (SG) • trivial rotation • all-frequency signals center intensity sharpness

  19. Spherical Gaussian (SG) • trivial rotation • all-frequency signals center intensity sharpness inner product: vector product:

  20. SG Mixtures Sum of Multiple SGs: Original SG, N = 7 SG, N = 3 SG, N = 1

  21. Microfacet BRDF Model • surface modeled by tiny mirror facets [Cook 82]

  22. Microfacet BRDF Model • surface modeled by tiny mirror facets [Cook 82] normal distribution shadow term fresnel term Represented by SG

  23. Parametric Models • single-lobe, analytic approximation • Cook-Torrance [Cook et al. 1981] • Ward [Ward 1992] • Blinn-Phong [Blinn 1977]

  24. Parametric BRDFs

  25. Anisotropic Parametric Models ground truth 7-lobe SGM nu=8, nv=128nu=25, nv=400nu=75, nv=1200

  26. Measured BRDFs BRDF from [Matusik03] svBRDF from [Wang08] & [Lawance06]

  27. Representation Efficiency • Parametric BRDFTexturing of original BRDF parameters isotropic : 7 float/texel: diffuse, specular, shininess Anisotropic: 8 float/texel: diffuse, specular, shininess u/v • Measured BRDFTexturing of SGs

  28. BRDF Slices o Normal Distributionin Half-vector Domain BRDF Slicein light-vector Half-vector Domain

  29. SG Warping • SG not closed under -1 • approx. by per-SG warp of D*

  30. SG Warping • SG not closed under -1 • approx. by per-SG warp of D*

  31. Parametric svBRDF Painting

  32. Outline • Reflectance Representation • Microfacet Model with SGs • Visibility Representation • Signed Spherical Distance Function • Lighting & Rendering o

  33. Visibility at one point scene binary visibility function x V(x,i)

  34. Visibility Prerequisite • Preserve sharp visibility boundary • inner productfor Diffuse Term • vector productfor Specular Term ? SGs ? SGs

  35. Spherical Signed Distance Function Vd(i0) i0 i1 Vd(i1) binary visibility, V(i) SSDF, Vd(i)

  36. SSDF-SG Product SSDF Visibility

  37. SSDF-SG Product p p ≈ p Approx. Visibility for p SSDF Visibility p p SG centered at p Approx. Visibility for p

  38. SSDF-SG Product p p ≈ p Approx. Visibility for p SSDF Visibility =0.329 p SG centered at p vector product Inner product

  39. Per-pixel Shading & Shadowing

  40. Outline • Reflectance Representation • Microfacet Model with SGs • Visibility Representation • Signed Spherical Distance Function • Lighting & Rendering o

  41. Local Light Source • Point light • directional light

  42. Environment Light for diffuse shading for specular shading prefiltered MIPMAP [Kautz et al. 2000] SGs (10 lobes) [Tsai and Shih 2006]

  43. Environment Light for diffuse shading for specular shading prefiltered MIPMAP [Kautz et al. 2000] SGs (10 lobes) [Tsai and Shih 2006]

  44. Environment + Local Lighting

  45. Rendering Summary: Diffuse Environment Light Microfacet Model

  46. Rendering Summary: Diffuse Visibilityin SSDF Environment Light Microfacet Model Cosine Termin SGs ● BRDF Slicein SGs Environmentin SGs

  47. Rendering Summary: Specular Visibilityin SSDF Environment Light Microfacet Model Cosine Termin SGs ● BRDF Slicein SGs PrefilteredEnvironment

  48. Performance Summary • Testing Machine • Intel Core2 Duo 3.2G CPU, 4GB memory • nVidiaGeforce 8800 Ultra graphics card

  49. Performance Summary • Testing Machine • Intel Core2 Duo 3.2G CPU, 4GB memory • nVidiaGeforce 8800 Ultra graphics card

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