A Wavelet Representation of Reflectance Functions

Analytical models of light reflection are in common use in computer graphics. However, models based on measured reflectance data promise increased realism by making it possible to simulate many more types of surfaces to a greater level of accuracy than with analytical models. They also require less expert knowledge about the illumination models and their parameters. There are a number of hurdles to using measured reflectance functions, however. The data sets are very large. A reflectance distribution function sampled at five degrees angular resolution, arguably sparse enough to miss highlights and other high frequency effects, can easily require over a million samples, which in turn amount to over four megabytes of data. These data then also require some form of interpolation and filtering to be used effectively. We examine issues of representation of measured reflectance distribution functions. In particular, we examine a wavelet basis representation of reflectance functions, and the algorithms required for efficient point-wise reconstruction of the BRDF. We show that the nonstandard wavelet decomposition leads to considerably more efficient algorithms than the standard wavelet decomposition. We also show that thresholding allows considerable improvement in running times, without unduly sacrificing image quality.

[1]  Pat Hanrahan,et al.  Wavelet radiosity , 1993, SIGGRAPH.

[2]  Turner Whitted,et al.  An improved illumination model for shaded display , 1979, CACM.

[3]  Stephen H. Westin,et al.  Predicting reflectance functions from complex surfaces , 1992, SIGGRAPH.

[4]  Peter Schröder,et al.  Spherical wavelets: efficiently representing functions on the sphere , 1995, SIGGRAPH.

[5]  Paul Lalonde,et al.  Acquiring and Using Realistic Reflectance Data in Computer Graphics Images , 1997 .

[6]  Donald P. Greenberg,et al.  An Efficient Radiosity Approach for Realistic Image Synthesis , 1986, IEEE Computer Graphics and Applications.

[7]  James F. Blinn,et al.  Models of light reflection for computer synthesized pictures , 1977, SIGGRAPH.

[8]  Nelson L. Max,et al.  Bidirectional reflection functions from surface bump maps , 1987, SIGGRAPH.

[9]  Gary W. Meyer,et al.  Wavelength dependent reflectance functions , 1994, SIGGRAPH.

[10]  E. J. Stollnitz,et al.  Wavelets for Computer Graphics : A Primer , 1994 .

[11]  Donald P. Greenberg,et al.  A radiosity method for non-diffuse environments , 1986, SIGGRAPH.

[12]  Bui Tuong Phong.  Illumination for computer generated pictures , 1975, Commun. ACM.

[13]  Gregory J. Ward,et al.  Measuring and modeling anisotropic reflection , 1992, SIGGRAPH.

[14]  Paul Lalonde,et al.  Generating Reflected Directions from BRDF Data , 1997 .

[15]  Gary W. Meyer,et al.  Newton’s Colors: Simulating Interference Phenomena in Realistic Image Synthesis , 1992 .

[16]  Stephen H. Westin,et al.  A global illumination solution for general reflectance distributions , 1991, SIGGRAPH.

[17]  Robert L. Cook,et al.  A Reflectance Model for Computer Graphics , 1987, TOGS.

[18]  Donald E. Knuth,et al.  The art of computer programming, volume 3: (2nd ed.) sorting and searching , 1998 .

[19]  David Salesin,et al.  Wavelets for computer graphics: a primer.1 , 1995, IEEE Computer Graphics and Applications.

[20]  I. Daubechies.  Ten Lectures on Wavelets , 1992 .

[21]  Pat Hanrahan,et al.  Reflection from layered surfaces due to subsurface scattering , 1993, SIGGRAPH.

[22]  Alain Fournier,et al.  Separating Reflection Functions for Linear Radiosity , 1995, Rendering Techniques.

[23]  James T. Kajiya,et al.  The rendering equation , 1998 .

[24]  James T. Kajiya,et al.  Anisotropic reflection models , 1985, SIGGRAPH.

[25]  Paul Lalonde,et al.  Filtered Local Shading in the Wavelet Domain , 1997, Rendering Techniques.

[26]  Alain Fournier,et al.  Light-Driven Global Illumination with a Wavelet Representation of Light Transport , 1996, Rendering Techniques.

[27]  Donald E. Knuth,et al.  Sorting and Searching , 1973 .