Take a look at the new version of this page: [ beta version ]. Tell us what you think.

ABSTRACT

In this paper we present an approximate method for accelerated computation of the final gathering step in a global illumination algorithm. Our method operates by decomposing the radiance field close to surfaces into separate far- and near-field components that can be approximated individually. By computing surface shading using these approximations, instead of directly querying the global illumination solution, we have been able to obtain rendering time speed ups on the order of 10x compared to previous acceleration methods. Our approximation schemes rely mainly on the assumptions that radiance due to distant objects will exhibit low spatial and angular variation, and that the visibility between a surface and nearby surfaces can be reasonably predicted by simple location and orientation-based heuristics. Motivated by these assumptions, our far-field scheme uses scattered-data interpolation with spherical harmonics to represent spatial and angular variation, and our near-field scheme employs an aggressively simple visibility heuristic. For our test scenes, the errors introduced when our assumptions fail do not result in visually objectionable artifacts or easily noticeable deviation from a ground-truth solution. We also discuss how our near-field approximation can be used with standard local illumination algorithms to produce significantly improved images at only negligible additional cost.

REFERENCES

• 1: Atkinson, K. E. 2000. The planar radiosity equation and its numerical solution. IMA Journal of Numerical Analysis 20, 303--332.
• 2: R. Basri , D. Jacobs, Lambertian Reflectance and Linear Subspaces, Weizmann Science Press of Israel, Jerusalem, Israel, 2000
• 3: Bekaert, P., Dutre, P., and Willems, Y. D. 1998. Final radiosity gather step using a monte carlo technique with optimal importance sampling. Tech. Rep. CW275.
• 4: Philip Dutre , Kavita Bala , Philippe Bekaert, Advanced Global Illumination, A. K. Peters, Ltd., Natick, MA, 2002
• 5: Epstein, R., Hallinan, P. W., and Yuille, A. L. 1995. 5 ± 2 eigenimages suffice: An empirical investigation of low-dimensional lighting models. In IEEE workshop on physics-based modeling in computer vision, 108--116.
• 6: Gautron. P. Krivanek, J., Pattanaik, S., and Bouatouch, K. 2004. A novel hemispherical basis for accurate and efficient rendering. In Rendering Techniques 2004: 15th Eurographics Workshop on Rendering, 321--330.
• 7: Gene Greger , Peter Shirley , Philip M. Hubbard , Donald P. Greenberg, The Irradiance Volume, IEEE Computer Graphics and Applications, v.18 n.2, p.32-43, March 1998 [doi>10.1109/38.656788]
• 8: Hottel, H. C., and Saforim. A. F. 1967. Radiative Transfer. McGraw Inc.
• 9: Henrik Wann Jensen, Realistic image synthesis using photon mapping, A. K. Peters, Ltd., Natick, MA, 2001
• 10: Jaroslav Krivanek , Pascal Gautron , Sumanta Pattanaik , Kadi Bouatouch, Radiance Caching for Efficient Global Illumination Computation, IEEE Transactions on Visualization and Computer Graphics, v.11 n.5, p.550-561, September 2005 [doi>10.1109/TVCG.2005.83]
• 11: Dani Lischinski , Filippo Tampieri , Donald P. Greenberg, Combining hierarchical radiosity and discontinuity meshing, Proceedings of the 20th annual conference on Computer graphics and interactive techniques, p.199-208, September 1993 [doi>10.1145/166117.166143]
• 12: Ravi Ramamoorthi , Pat Hanrahan, An efficient representation for irradiance environment maps, Proceedings of the 28th annual conference on Computer graphics and interactive techniques, p.497-500, August 2001 [doi>10.1145/383259.383317]
• 13: Ramamoorthi. R., and Hanrahan, P. 2001. The relationship between radiance and irradiance: Determining the illumination from images of a convex lambertian object. In Journal of the Optical Society of America.
• 14: Rathsfeld, A. 1999. Edge asymptotics for the radiosity equation over polyhedral boundaries. Mathematical Methods in the Applied Sciences 22, 3, 217--241.
• 15: Rushmeier, H. E., Patterson, C., and Veerasamy, A. 1993. Geometric simplification for indirect illumination calculations. In Graphics Interface.
• 16: Holly Edith Rushmeier, Realistic image synthesis for scenes with radiatively participating media, 1988
• 17: Annette Scheel , Marc Stamminger , Hans-Peter Seidel, Thrifty Final Gather for Radiosity, Proceedings of the 12th Eurographics Workshop on Rendering Techniques, p.1-12, June 25-27, 2001
• 18: Scheel, A., Stamminger, M., and Seidel, H. P. 2002. Grid based final gather for radiosity on complex scenes. In EUROGRAPHICS 2002, 547--555.
• 19: Francois X. Sillion , Claude Puech, Radiosity and Global Illumination, Morgan Kaufmann Publishers Inc., San Francisco, CA, 1994
• 20: Peter-Pike Sloan , Jan Kautz , John Snyder, Precomputed radiance transfer for real-time rendering in dynamic, low-frequency lighting environments, Proceedings of the 29th annual conference on Computer graphics and interactive techniques, July 23-26, 2002, San Antonio, Texas
• 21: Tabellion, E., and Lamorlette, A. 2004. An approximate global illumination system for computer generated films. In SIGGRAPH 2004. Computer Graphics Proceedings.
• 22: Ward, G. J., and Heckbert, P. 1992. Irradiance Gradients. In Third Eurographics Workshop on Rendering, 85--98.
• 23: 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
• 24: Zimmerman, K., and Shirley, P. 1995. A Two-Pass Realistic Image Synthesis Method for Complex Scenes. In Rendering Techniques '95 (Proceedings of the Sixth Eurographics Workshop on Rendering), 284--295.

INDEX TERMS

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

Additional Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.7 Three-Dimensional Graphics and Realism

Keywords:
approximate global illumination, final gather, spherical harmonics