Abstract
Most previous soft shadow algorithms have either suffered from aliasing, been too slow, or could only use a limited set of shadow casters and/or receivers. Therefore, we present a strengthened soft shadow volume algorithm that deals with these problems. Our critical improvements include robust penumbra wedge construction, geometry-based visibility computation, and also simplified computation through a four-dimensional texture lookup. This enables us to implement the algorithm using programmable graphics hardware, and it results in images that most often are indistinguishable from images created as the average of 1024 hard shadow images. Furthermore, our algorithm can use both arbitrary shadow casters and receivers. Also, one version of our algorithm completely avoids sampling artifacts which is rare for soft shadow algorithms. As a bonus, the four-dimensional texture lookup allows for small textured light sources, and, even video textures can be used as light sources. Our algorithm has been implemented in pure software, and also using the GeForce FX emulator with pixel shaders. Our software implementation renders soft shadows at 0.5--5 frames per second for the images in this paper. With actual hardware, we expect that our algorithm will render soft shadows in real time. An important performance measure is bandwidth usage. For the same image quality, an algorithm using the accumulated hard shadow images uses almost two orders of magnitude more bandwidth than our algorithm.
Supplemental Material
- AGRAWALA, M., RAMAMOORTHI, R., HEIRICH, A., AND MOLL, L. 2000. Efficient Image-Based Methods for Rendering Soft Shadows. In Proceedings of ACM SIGGRAPH 2000, ACM Press/ACM SIGGRAPH, New York. K. Akeley, Ed., Computer Graphics Proceedings, Annual Conference Series, ACM, 375--384. Google ScholarDigital Library
- AKENINE-MÖLLER, T., AND ASSARSSON, U. 2002. Approximate Soft Shadows on Arbitrary Surfaces using Penumbra Wedges. In 13th Euro-graphics Workshop on Rendering, Eurographics, 309--318. Google ScholarDigital Library
- ASSARSSON, U., AND AKENINE-MÖLLER, T. 2003. Interactive Rendering of Soft Shadows using an Optimized and Generalized Penumbra Wedge Algorithm. submitted to the Visual Computer.Google Scholar
- BERGERON, P. 1986. A General Version of Crow's Shadow Volumes. IEEE Computer Graphics and Applications 6, 9 (September), 17--28.Google ScholarDigital Library
- BRABEC, S., AND SEIDEL, H.-P. 2002. Single Sample Soft Shadows using Depth Maps. In Graphics Interface 2002, 219--228.Google Scholar
- BROTMAN, L. S., AND BADLER, N. I. 1984. Generating Soft Shadows with a Depth Buffer Algorithm. IEEE Computer Graphics and Applications 4, 10 (October), 5--12.Google ScholarCross Ref
- COHEN, M. F., AND WALLACE, J. R. 1993. Radiosity and Realistic Image Synthesis. Academic Press Professional. Google ScholarDigital Library
- CROW, F. 1977. Shadow Algorithms for Computer Graphics. In Computer Graphics (Proceedings of ACM SIGGRAPH 77), ACM, 242--248. Google ScholarDigital Library
- DRETTAKIS, G., AND FIUME, E. 1994. A Fast Shadow Algorithm for Area Light Sources Using Back Projection. In Proceedings of ACM SIGGRAPH 94, ACM Press/ACM SIGGRAPH, New York. A. Glassner, Ed., Computer Graphics Proceedings, Annual Conference Series, ACM, 223--230. Google ScholarDigital Library
- EVERITT, C., AND KILGARD, M. 2002. Practical and Robust Stenciled Shadow Volumes for Hardware-Accelerated Rendering. http://developer.nvidia.com/.Google Scholar
- FERNANDO, R., FERNANDEZ, S., BALA, K., AND GREENBERG, D. P. 2001. Adaptive Shadow Maps. In Proceedings of ACM SIGGRAPH 2001, ACM Press/ACM SIGGRAPH, New York. E. Fiume, Ed., Computer Graphics Proceedings, Annual Conference Series, ACM, 387--390. Google ScholarDigital Library
- HAINES, E., AND MÖLLER, T. 2001. Real-Time Shadows. In Game Developers Conference, CMP, 335--352.Google Scholar
- HAINES, E. 2001. Soft Planar Shadows Using Plateaus. Journal of Graphics Tools 6, 1, 19--27. Google ScholarDigital Library
- HART, D., DUTRÉ, P., AND GREENBERG, D. P. 1999. Direct Illumination with Lazy Visbility Evaluation. In Proceedings of ACM SIGGRAPH 99, ACM Press/ACM SIGGRAPH, New York. A. Rockwood, Ed., Computer Graphics Proceedings, Annual Conference Series, ACM, 147--154. Google ScholarDigital Library
- HECKBERT, P., AND HERF, M. 1997. Simulating Soft Shadows with Graphics Hardware. Tech. rep., Carnegie Mellon University, CMU-CS-97-104, January.Google Scholar
- HEIDMANN, T. 1991. Real Shadows, Real Time. Iris Universe, 18 (November), 23--31.Google Scholar
- HEIDRICH, W., BRABEC, S., AND SEIDEL, H.-P. 2000. Soft Shadow Maps for Linear Lights. In 11th Eurographics Workshop on Rendering, Eurographics, 269--280. Google ScholarDigital Library
- KAUTZ, J., AND MCCOOL, M. D. 1999. Interactive Rendering with Arbitrary BRDFs using Separable Approximations. In 10th Eurographics Workshop on Rendering, Eurographics, 281--292. Google ScholarDigital Library
- MARKOSIAN, L., KOWALSKI, M. A., TRYCHIN, S. J., BOURDEV, L. D., GOLDSTEIN, D., AND HUGHES, J. F. 1997. Real-Time Nonphotorealistic Rendering. In Proceedings of ACM SIGGRAPH 97, ACM Press/ACM SIGGRAPH, New York. T. Whitted, Ed., Computer Graphics Proceedings, Annual Conference Series, ACM, 415--420. Google ScholarDigital Library
- PARKER, S., SHIRLEY, P., AND SMITS, B. 1998. Single Sample Soft Shadows. Tech. rep., University of Utah, UUCS-98-019, October.Google Scholar
- REEVES, W. T., SALESIN, D. H., AND COOK, R. L. 1987. Rendering Antialiased Shadows with Depth Maps. In Computer Graphics (Proceedings of ACM SIGGRAPH 87), ACM, 283--291. Google ScholarDigital Library
- SEGAL, M., KOROBKIN, C., VAN WIDENFELT, R., FORAN, J., AND HAEBERLI, P. 1992. Fast Shadows and Lighting Effects Using Texture Mapping. In Computer Graphics (Proceedings of ACM SIGGRAPH 92), ACM, 249--252. Google ScholarDigital Library
- SLOAN, P.-P., KAUTZ, J., AND SNYDER, J. 2002. Precomputed Radiance Transfer for Real-Time Rendering in Dynamic, Low-Frequency Lighting Environments. ACM Transactions on Graphics 21, 3 (July), 527--536. Google ScholarDigital Library
- SOLER, C., AND SILLION, F. X. 1998. Fast Calculation of Soft Shadow Textures Using Convolution. In Proceedings of ACM SIGGRAPH 98, ACM Press/ACM SIGGRAPH, New York. M. Cohen, Ed., Computer Graphics Proceedings, Annual Conference Series, ACM, 321--332. Google ScholarDigital Library
- STAMMINGER, M., AND DRETTAKIS, G. 2002. Perspective Shadow Maps. ACM Transactions on Graphics 21, 3 (July), 557--562. Google ScholarDigital Library
- WILLIAMS, L. 1978. Casting Curved Shadows on Curved Surfaces. In Computer Graphics (Proceedings of ACM SIGGRAPH 92), ACM, 270--274. Google ScholarDigital Library
- WOO, A., POULIN, P., AND FOURNIER, A. 1990. A Survey of Shadow Algorithms. IEEE Computer Graphics and Applications 10, 6 (November), 13--32. Google ScholarDigital Library
Index Terms
- A geometry-based soft shadow volume algorithm using graphics hardware
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