Rendering Microsurface-Based Textures With Texels Phil Sutton Computer Graphics Laboratory California Institute of Technology Basis and Motivation The idea of texels and their use in rendering fur was put forth in Kajiya and Kay (1989). They used this method to render a furry teddy bear - the well-known Herbert. Unfortunately, Herbert has holes, and the background is visible through his head. Also, the ray tracer that produced Herbert is fragile and will not render anything but fur. The goal of this project is to implement texels such that they can be incorporated into a standard ray tracer. Main Ideas A texel is essentially an array that represents the density of the microsurfaces at each point. A ray travelling through the texel scatters with some probability. The contribution from all points along the ray is integrated using Monte Carlo techniques. The major difference between this project and Kajiya and Kay's is that here, texels are convex, overlapping solids instead of deformed cubes. These cubes do not tile space, which produces Herbert's holes. Overlapping solids (cylinders are the current focus) with a blending function will produce similar results with no holes, and can be inserted into existing ray tracers. Future Directions This summer the project will be extended to include microsurfaces other than fur. Some proposed textures are: leaves on trees, clouds, and tensors. Feedback and suggestions are welcome at the address below. References Kajiya, James T. and Kay, Timothy L. "Rendering Fur With Three Dimensional Textures," Computer Graphics, 23(3), July 1989, pp. 271-280. My home page: Philip Sutton E-Mail: pms@gg.caltech.edu

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