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The School of Computing
Colloquium |
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Dr. Pat Hanrahan Stanford University Host: Chuck Hansen February 8, 2001 EMCB 105 Refreshments 3:25 p.m. Lecture 3:40 p.m. Abstract Blinn and Newell invented reflection mapping at the University of Utah. Reflection mapping allows environment maps, that is, omnidirectional images acquired at a point in space, to be used as virtual light sources in rendering systems. Shortly afterwards, Miller and Hoffman proposed prefiltering the environment maps to create reflectance maps. Reflectance maps represent the reflection of the environment by a particular material. Reflectance Maps are also widely used in Computer Vision. The idea of prefiltering an environment map by the reflection function of the surface (more precisely, the bidirectional reflectance distribution function or BRDF) is widely discussed in both computer graphics and computer vision. Recently, working with my colleague Ravi Ramamoorthi, we have shown that reflection is a unique type of convolution. We derive a convolution theorem for reflection, where the BRDF and the environment are represented by coefficients of Spherical Harmonics. This allows us to interpret reflection from a signal processing point of view, where the BRDF is a filter with a given frequency response, and the lighting is the input signal. This framework is particularly useful for inverse rendering, which may be formulated as a problem of deconvolution. In this talk I will describe our theoretical framework, and then discuss applications to computer graphics and computer vision. Biography Pat Hanrahan is the CANON USA Professor of Computer Science and Electrical Engineering at Stanford University where he teaches computer graphics. His current research involves visualization, image synthesis, and graphics systems and architectures. Before joining Stanford he was a faculty member at Princeton. He has also worked at Pixar where he developed developed volume rendering software and was the chief architect of the RenderMan(TM) Interface \- a protocol that allows modeling programs to describe scenes to high quality rendering programs. Previous to Pixar he directed the 3D computer graphics group in the Computer Graphics Laboratory at New York Institute of Technology. Professor Hanrahan has received three university teaching awards. In 1993 he received an Academy Award for Science and Technology, the Spirit of America Creativity Award, the SIGGRAPH Computer Graphics Achievement Award; he was recently elected to the National Academy of Engineering. Return to 2000-2001 Colloquium Calendar |