All-Frequency Shadows Using Non-linear Wavelet Lighting Approximation
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Ren Ng
Stanford University |
Ravi Ramamoorthi Columbia University |
Pat Hanrahan
Stanford University |
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ACM Transactions on Graphics, July 2003
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Abstract
We present a method, based on pre-computed light transport, for real-time rendering of objects under all-frequency, time-varying illumination represented as a high-resolution environment map. Current techniques are limited to small area lights, with sharp shadows, or large low-frequency lights, with very soft shadows. Our main contribution is to approximate the environment map in a wavelet basis, keeping only the largest terms (this is known as a non-linear approximation). We obtain further compression by encoding the light transport matrix sparsely but accurately in the same basis. Rendering is performed by multiplying a sparse light vector by a sparse transport matrix, which is very fast. For accurate rendering, using non-linear wavelets is an order of magnitude faster than using linear spherical harmonics, the current best technique.
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Paper (Adobe Acrobat PDF) 1 MB (High Quality JPEG Compressed) 143 KB (Screen Resolution) 5 MB (Press Quality)
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Video (AVI Format) 400 x 300 AVI (4 min, 12 MB) 720 x 486 AVI (4 min, 42 MB) Both require divx codec.
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Slides
See Also
Triple Product Wavelet Integrals for All-Frequency Relighting (ACM SIGGRAPH 2004)
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