A Ray tracing algorithm for progressive radiosity

ABSTRACT

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.

REFERENCES

• 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: S. Chattopadhyay , A. Fujimoto, Bi-directional ray tracing, CG International '87 on Computer graphics 1987, p.335-343, June 1987, Karuizawa, Japan
• 4: Michael F. Cohen , Donald P. Greenberg, The hemi-cube: a radiosity solution for complex environments, ACM SIGGRAPH Computer Graphics, v.19 n.3, p.31-40, Jul. 1985
• 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: Michael F. Cohen , Shenchang Eric Chen , John R. Wallace , Donald P. Greenberg, A progressive refinement approach to fast radiosity image generation, Proceedings of the 15th annual conference on Computer graphics and interactive techniques, p.75-84, June 1988
• 7: Robert L. Cook , Thomas Porter , Loren Carpenter, Distributed ray tracing, Proceedings of the 11th annual conference on Computer graphics and interactive techniques, p.137-145, January 1984
• 8: Robert L. Cook, Stochastic sampling in computer graphics, ACM Transactions on Graphics (TOG), v.5 n.1, p.51-72, Jan. 1986 [doi>10.1145/7529.8927]
• 9: Mark A. Z. Dippé , Erling Henry Wold, Antialiasing through stochastic sampling, ACM SIGGRAPH Computer Graphics, v.19 n.3, p.69-78, Jul. 1985
• 10: Cindy M. Goral , Kenneth E. Torrance , Donald P. Greenberg , Bennett Battaile, Modeling the interaction of light between diffuse surfaces, Proceedings of the 11th annual conference on Computer graphics and interactive techniques, p.213-222, January 1984
• 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: James T. Kajiya, The rendering equation, ACM SIGGRAPH Computer Graphics, v.20 n.4, p.143-150, Aug. 1986
• 14: Malley, Thomas J. V., '~A Shading Method for Computer Generated Images," Master's Thesis, The University of Utah, 1988.
• 15: M Gregory Maxwell , J Michael Bailey , W Victor Goldschmidt, Calculations of the radiation configuration factor using ray casting, Computer-Aided Design, v.18 n.7, p.371-379, Sept. 1986 [doi>10.1016/0010-4485(86)90224-1]
• 16: Tomoyuki Nishita , Eihachiro Nakamae, Continuous tone representation of three-dimensional objects taking account of shadows and interreflection, ACM SIGGRAPH Computer Graphics, v.19 n.3, p.23-30, Jul. 1985
• 17: Holly Edith Rushmeier, Realistic image synthesis for scenes with radiatively participating media, 1988
• 18: Siegel, Robert and John R. Howell, Thermal Radiation Heat Transfer, Hemisphere Publishing Corp., Washington DC, 1981.
• 19: Gregory J. Ward , Francis M. Rubinstein , Robert D. Clear, A ray tracing solution for diffuse interreflection, Proceedings of the 15th annual conference on Computer graphics and interactive techniques, p.85-92, June 1988
• 20: Turner Whitted, An improved illumination model for shaded display, Communications of the ACM, v.23 n.6, p.343-349, June 1980 [doi>10.1145/358876.358882]

INDEX TERMS

Primary Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.3 Picture/Image Generation
          Subjects: Display algorithms

Additional Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.5 Computational Geometry and Object Modeling
          Subjects: Curve, surface, solid, and object representations
      I.3.7 Three-Dimensional Graphics and Realism
          Subjects: Visible line/surface algorithms

General Terms:
Algorithms