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Physically Based Shading - Realtime Rendering CH9
The document discusses concepts related to physically based shading and lighting in computer graphics. It covers topics like light as an electromagnetic wave, polarization, reflection, refraction, BRDF models, illumination, and Fresnel reflectance. The key aspects are modeling light physically, calculating reflectance using BRDF models, and accounting for effects like Fresnel reflectance at surfaces.
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Physically Based Shading - Realtime Rendering CH9
- 1. ITM-4B A0661106 Realtime RenderingCH9 PhysicallyBasedShading
- 2. Let the formof an object be what it may, —light, shade, and perspective will always make it beautiful. — John Constable
- 3. Realtime Rendering CH9 Light ShadingProcess Shading Model Material Blending 1 2 3 4 5 PhysicallyBasedShading
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- 11. Light 1 2 3 4 5 Light is modeled asan Electromagnetic Transverse Wave K E B PhysicallyBasedShading
- 12. K PhysicallyBasedShading Light 1 2 3 4 5 λ Wavelength λ Electric Field Magnetic Field E B MagneticVector B Electric Vector E Energy Transfer Direction Light is modeled as an Electromagnetic Transverse Wave
- 13. K PhysicallyBasedShading Light 1 2 3 4 5 λ Wavelength λ Electric Field Magnetic Field E B ElectricVector E Magnetic Vector B Energy Transfer Direction Light waves carry Energy
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- 15. PhysicallyBasedShading Light 1 2 3 4 5 Light waves carryEnergy Frequency Wavelength Light Speed Period Angular Frequency Wavenumber Refractive Index
- 16. PhysicallyBasedShading Light 1 2 3 4 5 Light waves carryEnergy Frequency Wavelength Light Speed Period Angular Frequency Wavenumber Refractive Index Wave Impedance Irradiance Time Spatial Position
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- 22. PhysicallyBasedShading Light 1 2 3 4 5 a n Constructive Interference DestructiveInterference Incoherent Addition Linearly Combined
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- 29. θb Surfaces PhysicallyBasedShading Light 1 2 3 4 5 λa = λb na nb = na nb θa sin( ) sin() Surface A Surface B λa λb na nb Reflection R e f r a c t i o n θa θb θa λa
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- 32. Surface Scattering PhysicallyBasedShading Light 1 2 3 4 5 Reflection Surface A SurfaceB R e f r a c t i o n Reflections Surface A Surface B Refractions
- 33. Surface A Surface B SurfaceScattering PhysicallyBasedShading Light 1 2 3 4 5 Reflections Refractions
- 34. Surface A Surface B SubsurfaceScattering PhysicallyBasedShading Light 1 2 3 4 5 Reflections Refractions Surface A Surface B
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- 40. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF l View Ray Vector v LightVector l Camera C Radiance View Ray Camera Position
- 41. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF l View Ray Vector v LightVector l Camera C Radiance View Ray Camera Position Radiance Intersection Point p
- 42. PhysicallyBasedShading Shading Process 1 2 3 4 5 Radiance View Ray Camera PositionRadiance Intersection Point BRDF l View Ray Vector v Light Vector l Camera C p
- 43. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF l View Ray Vector v Camera C LightVector l Surface Normal n Incident Light Reflected Light Irradiance Radiance
- 44. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF l View Ray Vector v Camera C LightVector l Surface Normal n Incident Light Reflected Light Irradiance Radiance I : Prevent case which under the surface II : Helmholtz Reciprocity III : Conservation of Energy
- 45. Incident Light Reflected Light Irradiance Radiance l Light Vector l Camera C p PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF l ViewRay Vector v Camera C Light Vector l Surface Normal n Radiance View Ray Camera Position Radiance Intersection Point
- 46. Incident Light Reflected Light Irradiance Radiance l Light Vector l Camera C p PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF l ViewRay Vector v Camera C Light Vector l Surface Normal n Radiance View Ray Camera Position Radiance Intersection Point Reflectance Equation
- 47. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF l View Ray Vector v Camera C LightVector l Surface Normal n Radiance Intersection Point
- 48. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF View Ray Vector v LightVector l Surface Normal n Tangent Normal t Radiance Intersection Point Input Radiance i Output Radiance o Output Vector o Input Vector i
- 49. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF Surface Normal n Tangent Normal t Radiance IntersectionPoint Input Radiance i Output Radiance o Output Vector o Input Vector i θi θo ϕo ϕi
- 50. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF Surface Normal n Tangent Normal t Radiance IntersectionPoint Input Radiance i Output Radiance o Output Vector o ϕi ϕo Input Vector i θi θo
- 51. PhysicallyBasedShading Shading Process 1 2 3 4 5 BRDF Surface Normal n Tangent Normal t Radiance IntersectionPoint Input Radiance i Output Radiance o Output Vector o ϕi ϕo Input Vector i θi θo BRDF
- 52. PhysicallyBasedShading Shading Process 1 2 3 4 5 Directional-Hemispherical Re f lectance Tangent Normal t InputRadiance i Output Radiance o Output Vector o ϕi ϕo Input Vector i θi θo
- 53. PhysicallyBasedShading Shading Process 1 2 3 4 5 l View Ray Vector v Camera C LightVector l Surface Normal n Radiance Intersection Point Directional-Hemispherical Re f lectance
- 54. PhysicallyBasedShading Shading Process 1 2 3 4 5 l View Ray Vector v Camera C LightVector l Surface Normal n Directional-Hemispherical Re f lectance Reflectance Equation
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- 65. PhysicallyBasedShading Shading Process 1 2 3 4 5 Illumination Light Vector LightColor Prevent Negative
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- 67. PhysicallyBasedShading Shading Model 1 2 3 4 5 Fresnel Re f lectance Surface A SurfaceB Surface Normal n Light Normal l n ∙ l l′  ri 2(n ∙ l)n
- 68. PhysicallyBasedShading Shading Model 1 2 3 4 5 Fresnel Re f lectance Surface A SurfaceB Surface Normal n Light Normal l n ∙ l l′  ri 2(n ∙ l)n ri = 2(n ∙ l)n − l
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- 75. PhysicallyBasedShading Shading Model 1 2 3 4 5 Fresnel Re f lectance Distinct ofColors Surface Normal n elll
- 76. PhysicallyBasedShading Shading Model 1 2 3 4 5 Fresnel Re f lectance Without FresnelReflectance With Fresnel Reflectance Comparison
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- 78. PhysicallyBasedShading Shading Model 1 2 3 4 5 F(θi) Fresnel Re f lectance External Reflectance F(0∘ )F(90∘ ) Surface Normal n Incident i Normal Incidence
- 79. PhysicallyBasedShading Shading Model 1 2 3 4 5 Fresnel Re f lectance External Reflectance F(θi)F(n, l) ≈ F0 + (1 − F0)(1 − (n ∙ l)+ )5 - >
- 80. Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 Glass CopperAluminum External Reflectance
- 81. Fresnel Re f lectance 75° PhysicallyBasedShading Shading Model 1 2 3 4 5 75° 75° GlassCopper Aluminum External Reflectance θi sin(θi)
- 82. sin(θi) Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 75° 75°75° sin(θi) External Reflectance
- 83. Foreshortened Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 e View RayVector v Surface Normal n1 Surface Normal n2 θ1 θ2 sin(θ1) sin(θ2)
- 84. Dielectric Materials &Values Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 F(0∘ )
- 85. Metal Materials &Values Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 F(0∘ )
- 86. Substance Materials &Values Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 F(0∘ )
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- 90. Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 Parameterizing F(0) - > Specular Diffuse ρss - > ColorCsurf - > Not Matel Matel 1 0 m
- 91. Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 Parameterizing F(0) - > Specular Diffuse ρss - > ColorCsurf - > m Not Matel Matel 1 0 #000000
- 92. Fresnel Re f lectance PhysicallyBasedShading Shading Model 1 2 3 4 5 Parameterizing Specular Diffuse Color m Not MatelMatel 1 0 Dielectric F(0) - > ρss - > Csurf - >
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- 96. PhysicallyBasedShading Shading Model 1 2 3 4 5 Fresnel Re f lectance Internal Reflectance sin(θc)= n1 n2 = ( 1 − F0 1 + F0 ) 2
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- 106. PhysicallyBasedShading Shading Model 1 2 3 4 5 NDF ∫m∈Θ D(m)(n ∙ m)dm Microfacet Normals D(m) SurfaceNormal n View Ray Vector v Surface Normal n
- 107. PhysicallyBasedShading Shading Model 1 2 3 4 5 NDF ∫m∈Θ D(m)(n ∙ m)dm Microfacet Normals D(m)= 1 Surface Normal n View Ray Vector v Surface Normal n
- 108. PhysicallyBasedShading Shading Model 1 2 3 4 5 NDF ∫m∈Θ D(m)(n ∙ m)dm Microfacet Normals D(m)= v ∙ n Surface Normal n View Ray Vector v Surface Normal n (n ∙ m) ∫m∈Θ
- 109. PhysicallyBasedShading Shading Model 1 2 3 4 5 NDF View Ray Vector v SurfaceNormal n Masking Function ∫m∈Θ = v ∙ n Distribution of Visible Normals (n ∙ m) D(m) G1(m, v)
- 110. PhysicallyBasedShading Shading Model 1 2 3 4 5 NDF G1(m, v) = χ+ (m∙ v) 1 + Λ(v) χ+ (x) = { 1, where x > 0, 0, where x ≤ 0. Positive Characteristic Function Masking Function
- 111. PhysicallyBasedShading Shading Model 1 2 3 4 5 micro-BRDF Lo(l, v) = ∫l∈Ω fr(l,v)Li(l)(n ∙ l)dl BRDF BRDF fr(l, v) = ∫m∈Ω fμ(l, v, m)G2(l, v, m)D(m) (m ∙ l)+ |n ∙ l| (m ∙ v)+ |n ∙ v| dm micro-BRDF Joint Masking-Shadowing Function
- 112. Masking Function PhysicallyBasedShading Shading Model 1 2 3 4 5 micro-BRDF BRDF fr(l, v) = ∫m∈Ω fμ(l,v, m)G2(l, v, m)D(m) (m ∙ l)+ |n ∙ l| (m ∙ v)+ |n ∙ v| dm micro-BRDF Joint Masking-Shadowing Function G2(l, v, m) = G1(v ∙ m)G1(l ∙ m)
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- 114. PhysicallyBasedShading Material 3 4 5 1 2 BRDF Models forSurface Re f lection Light Vector l Half Vector h View Ray Vector v le αh αh micro-BRDF
- 115. PhysicallyBasedShading Material 3 4 5 1 2 fspec(l, v) = F(h,l)G2(l, v, h)D(h) 4|n ∙ l||n ∙ v| BRDF Models for Surface Re f lection
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- 118. PhysicallyBasedShading Material 3 4 5 1 2 Beckmann NDF D(m) = χi (n∙ m) πα2 b(n ∙ m)4 exp ( (n ∙ m)2 − 1 a2 b(n ∙ m)2 )
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