“A Ray tracing algorithm for progressive radiosity” by Wallace, Elmquist and Haines

A new method for computing form-factors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemi-cube algorithm to determine form-factors. However, sampling problems inherent in the hemi-cube algorithm limit its usefulness for complex images. A more robust approach is described in which ray tracing is used to perform the numerical integration of the form-factor equation. The approach is tailored to provide good, approximate results for a low number of rays, while still providing a smooth continuum of increasing accuracy for higher numbers of rays. Quantitative comparisons between analytically derived form-factors and ray traced form-factors are presented.

1. Appel, Arthur, “Some Techniques for Shading Machine Renderings of Solids,” Proceedings of the Spring Joint Computer Conference 32, 1968, pp. 37-49.
2. Afro, James, “Backwards Ray Tracing,” Developments in Ray Tracing, SIGGRAPH Course Notes, Vol. 12, 1986.
3. Chattopadhyay, Subdeb, and Akira Fujimoto, ‘q3i- Directional Ray Tracing,” Computer Graphics 1987: Proceedings of CG International ’87, Springer-Verlag, Tokyo, 1987.
4. Cohen, Michael F. and Donald P. Greenberg, “A Radiosity Solution for Complex Environments,” Computer Graphics (SIGGRAPH ’85 Proceedings) 19, 3 (July 1985), pp. 31-40.
5. Cohen, Michael F., Donald P. Greenberg, David S. Immel, Philip J. Brock, “An Efficient Radiosity Approach for Realistic Image Synthesis,” IEEE Computer Graphics and Applications 6, 2 (Jan. 1986), pp. 2&35.
6. Cohen, Michael F., Shenchang Eric Chen, John R. Wallace, Donald P. Greenberg, “A Progressive Refinement Approach to Fast Radiosity Image Generation, .. Computer Graphics (SIGGRAPH “88 Proceedings) 22, 3 (August 1988), pp. 75-84.
7. Cook, Robert L., Thomas Porter and Loren Carpenter, “Distributed Ray Tracing,” Computer Graphics (SIGGRAPH ’84 Proceedings) 18, 3 (July 1984), pp. 137-145.
8. Cook, Robert L., “Stochastic Sampling in Computer Graphics,” A CM Transactions on Graphics 5, 3 (January 3241986), pp. 51-72.
9. Dippe, Mark A. Z., Erling Henry Wold, “Antialiasing Through Stochastic Sampling”, Computer Graphics (S{G- GRAPH ’85 Proceedings) 19, 3, pp. 69-78.
10. Goral, Cindy M., Kenneth E. Torrance, Donald P. Greenberg, Bennet Battaile, “Modeling the Interaction of Light Between Diffuse Surfaces,” Computer Graphics (SIGGRAPH ’84 Proceedings) 18, 3 (July 1984), pp. 213-222.
11. Gouraud, Henri, “Continuous Shading of Curved Surfaces,” 1LEE Transactions on Computers 20, 6 (June 1971), pp. 623-629.
12. Howell, John R., A Catalog of Radiation Co1~figuration Factors, McGraw-Hill, New York, 1982.
13. Kajiya, James T., “The Rendering Equation,” Computer Graphics (SIGGRAPH “86 Proceedings) 20, 4 (August 1986), pp. 143-150.
14. Malley, Thomas J. V., ‘~A Shading Method for Computer Generated Images,” Master’s Thesis, The University of Utah, 1988.
15. Maxwell, Gregory M., Michael J. Bailey, and Victor W. Goldschrnidt, “Calculations of the Radiation Confi~tration Factor Using Ray Casting,” Computer.Aided Design 18, 7 (September 1986), pp. 371-379.
16. Nishita, Tomoyuki and Eihachiro Nakamae, “Continuous Tone Representation 06 Three-Dimensional Objects Taking Account of Shadows and Interreflection,” Computer Graphics (SIGGRAPH ’85 Proceedings) 19, 3 (July 1985), pp. 22-30.
17. Rushmier, Holly E., ‘~Realistic Image Synthesis for Scenes With Radiatively Participating Media,” Doctoral Thesis, Cotnell University, 1988.
18. Siegel, Robert and John R. Howell, Thermal Radiation Heat Transfer, Hemisphere Publishing Corp., Washington DC, 1981.
19. Ward, Gregory J., Francis M. Rubinstein, Robert D. Clear, “A Ray Tracing Solutior~ for Diffuse Interreflection,”Computer Graphics (SIGGRAPH ’88 Proceedings) 22, 3 (August 1988), pp. 85-92.
20. Whitted, Turner, “An Improved Illumination Model for Shaded Display,” Communications of the A CM .32, 6 (June 1980), pp. 343-349.