Precomputed Radiance Transfer
Precomputed Radiance Transfer (PRT) is a computer graphics technique used to render a scene in real time with complex light interactions being precomputed to save time. Radiosity methods can be used to determine the diffuse lighting of the scene, however PRT offers a method to dynamically change the lighting environment.
When spherical harmonics are used to approximate the light transport function, only low-frequency effects can be handled with a reasonable number of parameters. Ren Ng extended this work to handle higher frequency shadows by replacing spherical harmonics with non-linear wavelets.
- Teemu Mäki-Patola (2003-05-05). "Precomputed Radiance Transfer" (PDF). Helsinki University of Technology. Retrieved 2008-02-25.
- Jan Kautz; Peter-Pike Sloan, Jaakko Lehtinen. "Precomputed Radiance Transfer: Theory and Practice". SIGGRAPH 2005 Courses. Retrieved 2009-02-25.
- Peter-Pike Sloan, Jan Kautz, and John Snyder. "Precomputed Radiance Transfer for Real-time rendering in Dynamic, Low-Frequency Lighting Environments". ACM Transactions on Graphics, Proceedings of the 29th Annual Conference on Computer Graphics and Interactive Techniques (SIGGRAPH), pp. 527-536. New York, NY: ACM Press, 2002. 
- NG, R., RAMAMOORTHI, R., AND HANRAHAN, P. 2003. All-Frequency Shadows Using Non-Linear Wavelet Lighting Approximation. ACM Transactions on Graphics 22, 3, 376–381. 
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