Global Illumination-Light Reflection Models
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Our ultimate goal in light reflection work is to derive an accurate, physically-based local light reflection model for arbitrary reflectance functions. Models developed approximately 25 years ago at the University of Utah [PHON75] have been improved [BLIN77] [COOK81] but are not sufficiently accurate or general, though they still dominate standard graphics pipelines. In its first years the Center contributed a sophisticated but computationally expensive model based on physical optics that incorporates the specular, directional diffuse, and uniform diffuse reflections by a surface [HE91] [HE92]. This past year, we introduced a new class of primitive functions with nonlinear parameters for representing reflectance functions. The functions are reciprocal, energy-conserving and expressive, and capture important phenomena such as off-specular reflection, increasing reflectance with angle of incidence, and retroreflection [LAFO97]. Most importantly, the representation is simple, compact, and uniform and has been verified by comparisons to our physically-based model and actual measurements.
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[BLIN77]J. F. Blinn, "Models of Light Reflection for Computer Synthesized Pictures", Computer Graphics Proceedings, Annual Conference Series, 1977, ACM SIGGRAPH, pp. 192-198.
[COOK81]R. L. Cook and K. Torrance, "A Reflectance Model for Computer Graphics", Computer Graphics Proceedings, 15(3), Annual Conference Series, 1981, ACM SIGGRAPH, pp. 307-316.
[HE91]* Xiao D. He, Kenneth E. Torrance, F. Sillion, and Donald P. Greenberg, "A Comprehensive Physical Model for Light Reflection," SIGGRAPH "91 Conference Proceedings, ACM, Volume 25, No. 4, July 1991.
[HE92]Xiao D. He, Patrick O. Heynen, Richard L. Phillips, Kenneth E. Torrance, David H. Salesin, and Donald P. Greenberg, "A Fast and Accurate Light Reflection Model," SIGGRAPH"92 Proceedings, Computer Graphics, 26(2), pp. 253-254, July, 1992.
[LAFO97]E. Lafortune, S. Foo, K. Torrance, D. Greenberg, "Non-Linear Approximation of Reflectance Functions", to appear in Computer Graphics Proceedings, Annual Conference Series, ACM SIGGRAPH, 1997
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