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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Reflection Models
Previous lecture
Phong model
Microfacet models
Gaussian height field on surface
Self-shadowing
Torrance-Sparrow Model
Today
Multiple importance sampling
Anisotropic reflection models
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Multiple Importance Sampling
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Multiple Importance Sampling
Reflection of a circular light source by a rough surface
Radius
Sh
inin
ess
Sampling the light source Sampling the BRDF
( ) ( )f x g x dx
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Multiple Importance Sampling
Two sampling techniques
Form weighted combination of samples
The balance heuristic
2, 2
2,2,
2 2,
~ ( )
( )
( )
i
ii
i
X p x
f XY
p X
1, 1
1,1,
1 1,
~ ( )
( )
( )
i
ii
i
X p x
f XY
p X
1 1, 2 2,i i iY wY w Y
1 1 2 21 2
( )( ) ( ) ( ) ( ) ( ) ( )
( ) ( )i
i
p xw x p x w x p x w x p x
p x p x
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Multiple Importance Sampling
Source: Veach and Guibas
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Anisotropic Reflection Model
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Anisotropic Reflection
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Quarterhorse
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Reflection from a Cylinder
T
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Reflection from a Cylinder
T
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Reflection from a Cylinder
T
L
ˆˆ( )
NR L
N
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Reflection from a Cylinder
T
L
ˆˆ( )
NR L
N
![Page 13: CS348B Lecture 17Pat Hanrahan, Spring 2005 Reflection Models Previous lecture Phong model Microfacet models Gaussian height field on surface Self-shadowing](https://reader035.vdocuments.mx/reader035/viewer/2022062804/5697bf731a28abf838c7eeeb/html5/thumbnails/13.jpg)
CS348B Lecture 17 Pat Hanrahan, Spring 2005
Reflection from a Cylinder
T
L
ˆˆ( )
NR L
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Anisotropic Reflection
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Shape of Anisotropic Highlights
From Lu, Koenderink, Kappers
Fibers tangent to the plane defined by the halfway vector reflect light
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Shape of Anisotropic Highlights
From Lu, Koenderink, Kappers
![Page 17: CS348B Lecture 17Pat Hanrahan, Spring 2005 Reflection Models Previous lecture Phong model Microfacet models Gaussian height field on surface Self-shadowing](https://reader035.vdocuments.mx/reader035/viewer/2022062804/5697bf731a28abf838c7eeeb/html5/thumbnails/17.jpg)
CS348B Lecture 17 Pat Hanrahan, Spring 2005
Kajiya-Kay Model
Diffuse
Specular
2ˆ ˆsin 1L T L
cos cos cos sin sinss
E L E L E L
L
E
T
ˆˆ( )
NR L
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Herbert
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Fiber Model
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Fiber Model
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Fiber Model
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Caustics
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Hair Appearance
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
Hair Appearance
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CS348B Lecture 17 Pat Hanrahan, Spring 2005
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CS348B Lecture 17 Pat Hanrahan, Spring 2005