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Issue No.12 - Dec. (2011 vol.17)
pp: 1795-1802
Philipp Schlegel , University of Zurich
Maxim Makhinya , University of Zurich
Renato Pajarola , University of Zurich
Direct volume rendering has become a popular method for visualizing volumetric datasets. Even though computers are continually getting faster, it remains a challenge to incorporate sophisticated illumination models into direct volume rendering while maintaining interactive frame rates. In this paper, we present a novel approach for advanced illumination in direct volume rendering based on GPU ray-casting. Our approach features directional soft shadows taking scattering into account, ambient occlusion and color bleeding effects while achieving very competitive frame rates. In particular, multiple dynamic lights and interactive transfer function changes are fully supported. Commonly, direct volume rendering is based on a very simplified discrete version of the original volume rendering integral, including the development of the original exponential extinction into a-blending. In contrast to a-blending forming a product when sampling along a ray, the original exponential extinction coefficient is an integral and its discretization a Riemann sum. The fact that it is a sum can cleverly be exploited to implement volume lighting effects, i.e. soft directional shadows, ambient occlusion and color bleeding. We will show how this can be achieved and how it can be implemented on the GPU.
Volume Rendering, Shadows, Ambient Occlusion, GPU Ray-Casting, Exponential Extinction.
Philipp Schlegel, Maxim Makhinya, Renato Pajarola, "Extinction-Based Shading and Illumination in GPU Volume Ray-Casting", IEEE Transactions on Visualization & Computer Graphics, vol.17, no. 12, pp. 1795-1802, Dec. 2011, doi:10.1109/TVCG.2011.198
[1] U. Behrens and R. Ratering, Adding shadows to a texture-based volume renderer. In Proceedings IEEE Symposium on Volume Visualization, pages 39–46, 1998.
[2] S. Bruckner and E. Groller, Enhancing depth-perception with flexible volumetric halos. IEEE Transactions on Visualization and Computer Graphics, 13: 1 344–1351, 2007.
[3] F. C. Crow, Summed-area tables for texture mapping. In Proceedings of the 11th annual conference on Computer graphics and interactive techniques, SIGGRAPH, pages 207–212, 1984.
[4] J. Díaz, P.-P. Vázquez, I. Navazo, and F. Duguet, Real-time ambient occlusion and halos with summed area tables. Computers & Graphics, 34 (4): 337–350, August 2010.
[5] P. Dubois and G. Rodrigue, An analysis of the recursive doubling algorithm. In D. H. L. D. J. Kuck, and A. H. Sameh editors, , High Speed Computer and Algorithm Organization, pages 299–305. Academic Press, 1977.
[6] K. Engel, M. Hadwiger, J. M. Kniss, C. Rezk-Salama, and D. Weiskopf, Real-Time Volume Graphics. A. K. Peters, Ltd., 2006.
[7] K. Engel, M. Kraus, and T. Ertl, High-quality pre-integrated volume rendering using hardware-accelerated pixel shading. In Proceedings ACM SIGGRAPH/EUROGRAPHICS Workshop on Graphics Hardware, pages 9–16, 2001.
[8] C. Everitt, Interactive order-independent transparency. Technical report, NVIDIA Corp., 2001.
[9] M. Hadwiger, P. Ljung, C. Rezk-Salama, and T. Ropinski, Advanced illumination techniques for GPU-based volume raycasting. ACM SIG-GRAPH Course Notes, 2009.
[10] J. Hensley, T. Scheuermann, G. Coombe, M. Singh, and A. Lastra, Fast summed-area table generation and its applications. Computer Graphics Forum, 24: 547–555, 2005.
[11] F. Hernell, P. Ljung, and A. Ynnerman, Local ambient occlusion in direct volume rendering. IEEE Transactions on Visualization and Computer Graphics, 16 (4): 548–559, July/August 2010.
[12] H. W. Jensen, Realistic image synthesis using photon mapping. A. K. Peters, Ltd., 2001.
[13] J. Kniss, G. Kindlmann, and C. Hansen, Multidimensional transfer functions for interactive volume rendering. IEEE Transactions on Visualization and Computer Graphics, 8 (3): 270–285, 2002.
[14] J. Kniss, S. Premoze, C. Hansen, and D. Ebert, Interactive translucent volume rendering and procedural modeling. In Proceedings IEEE Visualization, pages 109–116, 2002.
[15] M. Kraus and K. Bürger, Interpolating and downsampling RGBA volume data. In Proceedings VMV, pages 323–332, 2008.
[16] J. Kruger and R. Westermann, Acceleration techniques for GPU-based volume rendering. In Proceedings IEEE Visualization, pages 287–292, 2003.
[17] H. Landis, Production-ready global illumination. In Siggraph Course Notes, volume 16, 2002.
[18] M. Malmer, F. Malmer, U. Assarsson, and N. Holzschuch, Fast pre-computed ambient occlusion for proximity shadows. Journal of graphics tools, 12 (2): 59–71, April 2007.
[19] N. Max, Optical models for direct volume rendering. IEEE Transactions on Visualization and Computer Graphics, 1 (2): 99–108, June 1995.
[20] A. Méndez, M. Sbert, and J. Catà, Real-time obscurances with color bleeding. In Proceedings Spring Conference on Computer Graphics, pages 171–176, 2003.
[21] A. Méndez-Feliu and M. Sbert, From obscurances to ambient occlusion: A survey. The Visual Computer, 25 (2): 181–196, February 2008.
[22] K. D. Moreland, Fast High Accuracy Volume Rendering. PhD thesis, The University of New Mexico, 2004.
[23] G. Papaioannou, M. L. Menexi, and C. Papadopoulos, Real-time volume-based ambient occlusion. IEEE Transactions on Visualization and Computer Graphics, 16 (5): 752–762, September/October 2010.
[24] T. Porter and T. Duff, Compositing digital images. In Proceedings ACM SIGGRAPH, pages 253–259, 1984.
[25] T. Ropinski, C. Döring, and C. Rezk-Salama, Interactive volumetric lighting simulating scattering and shadowing. In Proceedings IEEE Pacific Visualization Symposium, pages 169–176, 2010.
[26] T. Ropinski, J. Kasten, and K. Hinrichs, Efficient shadows for GPU-based volume raycasting. In Proceedings International Conference on Computer Graphics, Visualization and Computer Vision (WSCG), pages 17–24, 2008.
[27] T. Ropinski, J. Meyer-Spradow, S. Diepenbrock, J. Mensmann, and K. H. Hinrichs, Interactive volume rendering with dynamic ambient occlusion and color bleeding. Computer Graphics Forum, 27 (2): 567–576, 2008.
[28] M. Ruiz, I. Boada, I. Viola, S. Bruckner, M. Feixas, and M. Sbert, Obscurance-based volume rendering framework. In Proceedings IEEE/EG Symposium on Volume and Point-Based Graphics, pages 113– 120, 2008.
[29] H. Scharsach, Advanced GPU raycasting. In Proceedings Central European Seminar on Computer Graphics (CESCG), pages 69–76, 2005.
[30] P. Schlegel and R. Pajarola, Layered volume splatting. In Proceedings International Symposium on Visual Computing, pages 1–12, 2009.
[31] M. Schott, V. Pegoraro, C. Hansen, K. Boulanger, and K. Bouatouch, A directional occlusion shading model for interactive direct volume rendering. Computer Graphics Forum, 28 (3): 855–862, June 2009.
[32] P. Shanmugam and O. Arikan, Hardware accelerated ambient occlusion techniques on GPUs. In Proceedings Symposium on Interactive 3D Graphics and Games, pages 73–80. ACM SIGGRAPH, 2007.
[33] S. Stegmaier, M. Strengert, T. Klein, and T. Ertl, A simple and flexible volume rendering framework for graphics-hardware–based raycasting. In Proceedings International Workshop on Volume Graphics, pages 187– 195, 2005.
[34] L. Westover, Footprint evaluation for volume rendering. In Proceedings ACM SIGGRAPH, pages 367–376. ACM SIGGRAPH, 1990.
[35] L. Williams, Casting curved shadows on curved surfaces. In Proceedings ACM SIGGRAPH, pages 270–274, 1978.
[36] C. Zhang and R. Crawfis, Shadows and soft shadows with participating media using splatting. IEEE Transactions on Visualization and Computer Graphics, 9 (2): 139–149, 2003.
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