Refraction & BSDFs CS295, Spring 2017 Shuang Zhao Computer - - PowerPoint PPT Presentation

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Refraction & BSDFs CS295, Spring 2017 Shuang Zhao Computer - - PowerPoint PPT Presentation

Sep 17, 2022 220 likes •400 views

Refraction & BSDFs CS295, Spring 2017 Shuang Zhao Computer Science Department University of California, Irvine CS295, Spring 2017 Shuang Zhao 1 Last Lecture Bidirectional path tracing II CS295, Spring 2017 Shuang Zhao 2 Todays

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Refraction & BSDFs

CS295, Spring 2017 Shuang Zhao

Computer Science Department University of California, Irvine

CS295, Spring 2017 Shuang Zhao 1

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Last Lecture

  • Bidirectional path tracing II

CS295, Spring 2017 Shuang Zhao 2

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Today’s Lecture

  • Refraction & BSDFs
  • How light interacts with refractive interfaces (e.g.,

glass)

CS295, Spring 2017 Shuang Zhao 3

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Recap: Rendering Equation

CS295, Spring 2017 Shuang Zhao 4

= +

= +

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BRDF BTDF

Reflection and Transmission

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Reflected Radiance Lr Transmitted Radiance Lt

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Bidirectional Scattering Distribution Function (BSDF)

BSDFs

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Rendering Equation

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= +

= +

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Smooth Dielectric BSDF

  • Used to model smooth interfaces

like glass and water

  • Snell’s law: η1 sinθ1 = η2 sinθ2

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Incident Reflected Refracted Material interface

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Smooth Dielectric BSDF

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Fresnel term

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Radiance Scaling

  • When light enters a medium with a higher refractive

index, the same light energy is squeezed into a smaller volume, causing the radiance along each ray to increase

CS295, Spring 2017 Shuang Zhao 10

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Radiance Scaling

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(conservation of energy)

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Smooth Dielectric BSDF

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Fresnel term

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Smooth Dielectric BSDF

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Fresnel term

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Remarks

  • The scaling of (η2/η1)2 should only be applied

for radiance L, NOT importance W since there is no “conservation of energy” for W

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Rough Dielectric BSDFs

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[Walter et al. 2009] [Heitz et al. 2016]

Microfacet Models for Refraction through Rough Surfaces Multiple-Scattering Microfacet BSDFs with the Smith Model

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Next Lecture

  • Radiative transfer
  • The mathematical model to simulate light scattering

in participating media (e.g., smoke) and translucent materials (e.g., marble and skin)

  • Volume path tracing
  • Generalizing the path tracing algorithm to handle

participating media

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