UMD CMSC 828V - A 
Frequency 
Analysis 
o f
Light
 Transport
 (29 pages)

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A 
Frequency 
Analysis 
o f
Light
 Transport




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View the full content.
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A 
Frequency 
Analysis 
o f
Light
 Transport


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Pages:
29
School:
University of Maryland, College Park
Course:
Cmsc 828v - Advanced Topics in Information Processing

Unformatted text preview:

A Frequency Analysis of Light Transport Fr do Durand Nicolas Holzschuch Cyril Soler Eric Chan Fran ois Sillion Images and Material provided by Fr do Durand and the paper SIGGRAPH 2005 Light Transport Light travels from the source and is ltered and re ected Example The goal of this work is to study this in the frequency domain Why frequency domain Because something in the image is Sharp Blurred Sharp HIGH frequencies DisconMnuity Edges Blurred LOW frequencies SoP Shadows indirect illuminaMon Depth of Field Light Field ParameterizaMon angle v or space x Central ray local light eld Area Light v angle Ray space x space Area Light v angle Fourier space x space The Flow of Light Transport Transport in free space Occlusion BRDF The Flow of Light Transport The e ects can be modeled in frequency domain They involve Shearing Convolu on in spaMal domain Mul plica on in the frequency domain Transport in Free Space Shear x x v d d vd x x v x space Fourier space v angle Ray space v angle v angle Ray space x space x space Occlusion Planar occluders MulMplicaMon for SpaMal ConvoluMon in Frequency Blocker funcMon Fourier space Blocker spectrum Transport again Blockers Light source Receiver BRDF BRDF integraMon is convoluMon in spaMal domain recall from Spherical Harmonics LighMng x BRDF v angle v angle Convolu on in spaMal domain is Mul plica on in frequency domain x space BRDF spectrum x space Curvature Treat the curved surface as a plane Rotate the light direcMons i e Shearing So it s also shearing in frequency domain AdapMve Sampling Example Blocker distance Curvature BRDF Results Uniform 20k Sampling AdapMve 20k Sampling Sample Pa ern AdapMve Wavelet Rendering Ryan S Overbeck Craig Donner Ravi Ramamoorthi Images and Material provided by Ryan S Overbeck and the SIGGRAPH Asia 2009 paper Overview AdapMve super sampling Sampling in the image space mul scale wavelet domain The sampling rate on di erent scales of wavelets adapts to the details of the image Wavelets Wavelets are



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o f
Light
 Transport
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 Transport
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