Raanan Fattal
Abstract
Light traveling through semi-transparent media such as smoke and marble is absorbed and scattered. To achieve proper realistic visualizations of such media, illumination algorithms must account for these events. In this article, we present a new method for solving the Radiative Transport Equation, which models such evolution of light. The new method falls into the category of the Discrete Ordinates Method and inherits its generality and computational lightness. This method is known to suffer from two main shortcomings, namely false scattering and the ray effect, which we avoid in our new method. By propagating the light using low-dimensional maps of rays we detach their transport from the Eulerian grid and use fine angular discretizations. Thus, the scattering effect at each scattering generation is eliminated and the ray effect is significantly reduced at no additional memory requirements. Results demonstrate the new method's efficiency, ability to produce high-quality approximations, and its usefulness for a wide range of computer graphics applications.
- Arquès, D. and Michelin, S. 1996. Proximity radiosity: Exploiting coherence to accelerate form factor computations. In Rendering Techniques, 143--152. Google Scholar
Digital Library
- Behrens, U. and Ratering, R. 1998. Adding shadows to a texture-based volume renderer. In Proceedings of the IEEE Symposium on Volume Visualization (VVS'98). ACM Press, New York, 39--46. Google ScholarDigital Library
- Bhate, N. and Tokuta, A. 1992. Photorealistic volume rendering of media with directional scattering. In Proceedings of the 3rd Eurographics Workshop on Rendering, 227--245.Google Scholar
- Cerezo, E., Perez-Cazorla, F., Pueyo, X., Seron, F., and Sillion, F. 2005. A survey on participating media rendering techniques. In the Visual Computer.Google Scholar
- Chandrasekhar, S. 1950. Radiative Transfer. Dover, New York.Google Scholar
- Coelho, P. J. 2002. Bounded skew high-order resolution schemes for the discrete ordinates method. J. Comput. Phys. 175, 2, 412--437. Google ScholarDigital Library
- Coelho, P. J. 2004. A modified version of the discrete ordinates method for radiative heat transfer modelling. Comput. Mechanics 33, 375--388.Google ScholarCross Ref
- Cohen, M. F., Chen, S. E., Wallace, J. R., and Greenberg, D. P. 1988. A progressive refinement approach to fast radiosity image generation. In Proceedings of the ACM SIGGRAPH'88. ACM Press, New York, 75--84. Google ScholarDigital Library
- Dobashi, Y., Kaneda, K., Yamashita, H., Okita, T., and Nishita, T. 2000. A simple, efficient method for realistic animation of clouds. In Proceedings of the 27th Annual Conference on Computer Graphics and Interactive Techniques (SIGGRAPH'00). ACM Press/Addison-Wesley, New York, 19--28. Google ScholarDigital Library
- Gortler, S., Cohen, M. F., and Slusallek, P. 1994. Radiosity and relaxation methods. IEEE Comput. Graph. Appl. 14, 6, 48--58. Google ScholarDigital Library
- Hanrahan, P. and Krueger, W. 1993. Reflection from layered surfaces due to subsurface scattering. In Proceedings of the 20th Annual Conference on Computer Graphics and Interactive Techniques (SIGGRAPH'93). ACM, New York, 165--174. Google ScholarDigital Library
- Hottel, H. and Sarofim, A. 1967. Radiative Transfer. McGraw-Hill.Google Scholar
- Jensen, H. W. and Christensen, P. H. 1998. Efficient simulation of light transport in scences with participating media using photon maps. In Proceedings of the ACM SIGGRAPH'98. ACM Press, New York, 311--320. Google ScholarDigital Library
- Jensen, H. W., Marschner, S. R., Levoy, M., and Hanrahan, P. 2001. A practical model for subsurface light transport. In Proceedings of the 28th Annual Conference on Computer Graphics and Interactive Techniques (SIGGRAPH'01). ACM, New York, 511--518. Google ScholarDigital Library
- Jessee, J. P. and Fiveland, W. A. 1997. Bounded, high-resolution differencing schemes applied to the discrete ordinates method. J. Thermophys. Heat Transfer 11, 4, 540--548.Google ScholarCross Ref
- Kajiya, J. T. and Herzen, B. P. V. 1984. Ray tracing volume densities. In Proceedings of the ACM SIGGRAPH'84. ACM Press, New York, 165--174. Google ScholarDigital Library
- Lafortune, E. P. and Willems, Y. D. 1996. Rendering participating media with bidirectional path tracing. In Proceedings of the Eurographics Workshop on Rendering Techniques'96. Springer, 91--100. Google ScholarDigital Library
- Languenou, E., Bouatouch, K., and Chelle, M. 1994. Global illumination in presence of participating media with general properties. In Proceedings of the 5th Eurographics Workshop on Rendering, 71--86.Google Scholar
- Leveque, R. J. 2002. Finite Volume Methods for Hyperbolic Problems, 1st ed. Cambridge Texts in Applied Mathematics.Google Scholar
- Liu, F., B. H. A. and Pollard, A. 1996. Spatial differencing schemes of the discrete-ordinates method. Numer. Heat Transfer B 30, 23.Google ScholarCross Ref
- Max, N. L. 1994. Efficient light propagation for multiple anisotropic volume scattering. In 5th Eurographics Workshop on Rendering, 87--104.Google Scholar
- Pattanaik, S. N. and Mudur, S. P. 1993. Computation of global illumination in a participating medium by Monte Carlo simulation. The J. Vis. Comput. Animation 4, 3, 133--152.Google ScholarCross Ref
- Pauly, M., Kollig, T., and Keller, A. 2000. Metropolis light transport for participating media. In (Rendering Techniques 2000) Proceedings of the 11th Eurographics Workshop on Rendering, B. Peroche and H. Rushmeier, eds. Springer, 11--22. Google ScholarDigital Library
- Perez, F., Pueyo, X., and Sillion, F. X. 1997. Global illumination techniques for the simulation of participating media. In Proceedings of the Rendering Techniques'97. Springer, 309--320. Google ScholarDigital Library
- Premoze, S., Ashikhmin, M., Ramamoorthi, R., and Nayar, S. 2004. Rendering of multiple scattering effects in participating media. In Eurographics Symposium on Rendering.Google Scholar
- Ramankutty, M. A. and Crosbie, A. L. 1997. Modified discrete ordinates solution of radiative transfer in two-dimensional rectangular enclosures. J. Quantitative Spectroscopy Radiative Transfer 57, 107--140.Google ScholarCross Ref
- Rushmeier, H. 1988. Realistic image sythesis for scenes with radiatively participating media. Ph.D. thesis, Cornell University. Google ScholarDigital Library
- Sigel, R. and Howell, J. 1992. Thermal Radiation Heat Transfer, 3rd ed. Hemisphere. Washington, DC.Google Scholar
- Sillion, F. X. 1995. A unified hierarchical algorithm for global illumination with scattering volumes and object clusters. IEEE Trans. Visualiz. Comput. Graph. 1, 3, 240--254. Google ScholarDigital Library
- Stam, J. 1995. Multiple scattering as a diffusion process. In Proceedings of the Rendering Techniques'95, P. M. Hanrahan and W. Purgathofer, eds. Springer, 41--50.Google ScholarCross Ref
- Stam, J. 2001. An illumination model for a skin layer bounded by rough surfaces. In Proceedings of the 12th Eurographics Workshop on Rendering Techniques, 39--52. Google ScholarDigital Library
- Zienkiewicz, O. and Taylor, R. 2000. The Finite Element Method. Butterworth-Heinemann.Google Scholar
Index Terms
- Participating media illumination using light propagation maps
Recommendations
Radiance caching for participating media
In this article we present a novel radiance caching method for efficiently rendering participating media using Monte Carlo ray tracing. Our method handles all types of light scattering including anisotropic scattering, and it works in both homogeneous ...
Efficient Simulation of Light Transport in Scenes with Participating Media Using Photon Maps
Seminal Graphics Papers: Pushing the Boundaries, Volume 2This paper presents a new method for computing global illumination in scenes with participating media. The method is based on bidirectional Monte Carlo ray tracing and uses photon maps to increase efficiency and reduce noise. We remove previous ...
Epipolar sampling for shadows and crepuscular rays in participating media with single scattering
I3D '10: Proceedings of the 2010 ACM SIGGRAPH symposium on Interactive 3D Graphics and GamesScattering in participating media, such as fog or haze, generates volumetric lighting effects known as crepuscular or god rays. Rendering such effects greatly enhances the realism in virtual scenes, but is inherently costly as scattering events occur at ...
Reviews
Eugene Zhang
Realistic rendering of semi-transparent objects, such as smoke and marble, needs to address the absorption and scattering of light as it travels through the media. This is described by the radiative transport equation, which is difficult to solve due to the high dimensionality of the problem and insufficient resolutions in modeling orientations. The discrete ordinates method, a widely used solver based on finite element analysis, suffers from false scattering and ray effect that refer, respectively, to the loss of sharp light beams due to numerical smoothing and light travel in fictitious directions. Fattal provides an elegant improvement to this method without significantly increasing the computational cost and memory requirement. The basic idea is to propagate light using lower-dimensional maps, which separates light transport from the underlying Eulerian mesh and allows higher angular resolution. This approach greatly minimizes the smoothing of sharp light beams (false scattering) and reduces the number of false propagation directions (the ray effect). In addition, the use of low-dimensional maps in the process does not increase the memory usage or the computational cost. Computer graphics researchers, game developers, and technical directors at production houses will benefit most from this work. In addition, heat transfer engineers and fluid scientists could also benefit from the new development presented. Online Computing Reviews Service
Access critical reviews of Computing literature here
Become a reviewer for Computing Reviews.
Comments