TRAVERSING A BVH CUT TO EXPLOIT RAY COHERENCE

R. Torres, P. J. Martín, A. Gavilanes

Abstract

In this paper we study how to deal with the ray incoherence that naturally arises in path tracing-based systems. We introduce the notion of BVH Cut to split the tree into a forest of disjoint subtrees. We will use it to filter the rays that are successively generated by the path tracing algorithm. Each subtree is then traversed by its corresponding group of rays. Despite the overload of filtering all the rays each time, a significant profit is achieved. Nevertheless, constructing a BVH cut is a challenging task, because it can lead to a huge amount of work if the same rays belongs to many groups. Thus, we present two kind of building heuristics: structural heuristics that characterizes the root of a subtree by a property (the node’s depth or the surface area of its bounding volume in this paper), and optimization heuristics that are based on the Simulated Annealing method. The performance of traversing the cuts so built has been experimentally analyzed over four usual scenes, using two popular implementations of the subtree traversal (persistent while-while / persistent packet). The results show a relevant saving time w.r.t. the classic BVH traversal, that grows as the ray incoherence increases. The best saving ranges from 32.0% / 40.9% for structural heuristics, to 32.0% / 51.7% for cuts built with Simulated Annealing.

References

  1. Aila, T. and Karras, T. (2010). Architecture considerations for tracing incoherent rays. In Proceedings of the High-Performance Graphics 2010.
  2. Aila, T. and Laine, S. (2009). Understanding the efficiency of ray traversal on GPUs. In Proceedings of HighPerformance Graphics 2009, pages 145-149.
  3. Boulos, S., Edwards, D., Lacewell, J. D., Kniss, J., Kautz, J., Wald, I., and Shirley, P. (2007). Packet-based Whitted and Distribution Ray Tracing. In Proceedings of Graphics Interface 2007, pages 177-184.
  4. Boulos, S., Wald, I., and Benthin, C. (2008). Adaptive ray packet reordering. Symposium on Interactive Ray Tracing, 0:131-138.
  5. Ernst, M. and Greiner, G. (2007). Early split clipping for bounding volume hierarchies. In Proceedings of the 2007 IEEE Symposium on Interactive Ray Tracing, pages 73-78.
  6. Foley, T. and Sugerman, J. (2005). KD-tree acceleration structures for a GPU raytracer. In HWWS'05 Conference on Graphics Hardware, pages 15-22.
  7. Garanzha, K. and Loop, C. (2010). Fast ray sorting and breadth-first packet traversal for GPU ray tracing. In Eurographics, volume 29.
  8. Goldsmith, J. and Salmon, J. (1987). Automatic creation of object hierarchies for ray tracing. IEEE Computer Graphics and Application, 7(5):14-20.
  9. Gribble, C. P. and Ramani, K. (2008). Coherent ray tracing via stream filtering. In IEEE/Eurographics Symposium on Interactive Ray Tracing, pages 59-66.
  10. Günther, J., Popov, S., Seidel, H.-P., and Slusallek, P. (2007). Realtime ray tracing on GPU with BVH-based packet traversal. In Proceedings of the Eurographics Symposium on Interactive Ray Tracing, pages 113- 118.
  11. Horn, D. R., Sugerman, J., Mike, H., and Hanrahan, P. (2007). Interactive KD-tree GPU raytracing. In I3D'07: Proceedings of the symposium on Interactive 3D graphics and games, pages 167-174.
  12. Ize, T., Wald, I., and Parker, S. G. (2007). Asynchronous BVH construction for ray tracing dynamic scenes on parallel multi-core architectures. In Proceedings of the Eurographics Symposium on Parallel Graphics and Visualization, pages 101-108.
  13. Kajiya, J. T. (1986). The rendering equation. SIGGRAPH Computer Graphics, 20(4):143-150.
  14. Mansson, E., Munkberg, J., and Akenine-Moller, T. (2007). Deep coherent ray tracing. In RT 7807: Proceedings of the 2007 IEEE Symposium on Interactive Ray Tracing, pages 79-85.
  15. Navratil, P. A., Fussell, D. S., Lin, C., and Mark, W. R. (2007). Dynamic ray scheduling to improve ray coherence and bandwidth utilization. In RT 7807: Proceedings of the 2007 IEEE Symposium on Interactive Ray Tracing, pages 95-104.
  16. Noguera, J. M. and Uren˜a, C. and and García, R. J. (2009). A vectorized traversal algorithm for ray-tracing. In International Conference on Computer Graphics Theory and Applications (GRAPP 2009), pages 58-63.
  17. Park, S. K. and Miller, K. W. (1988). Random number generator: Good ones are hard to find. Communications of the ACM, 31(10):1192-1201.
  18. Pharr, M., Kolb, C., Gershbein, R., and Hanrahan, P. (1997). Rendering complex scenes with memory-coherent ray tracing. In SIGGRAPH 7897: Proceedings of the 24th annual conference on Computer graphics and interactive techniques, pages 101-108.
  19. Popov, S., Günther, J., Seidel, H.-P., and Slusallek, P. (2007). Stackless KD-tree traversal for high performance GPU ray tracing. Computer Graphics Forum (Proceedings of Eurographics), 26(3):415-424.
  20. Ramani, K., Gribble, C. P., and Davis, A. (2009). Streamray: A stream filtering architecture for coherent ray tracing. In Internationa Conference on Architectural Support for Programming Languajes and Operating System, pages 325-336.
  21. Torres, R., Martín, P. J., and Gavilanes, A. (2009). Ray casting using a roped BVH with CUDA. In Proc. Spring Conference on Computer Graphics, pages 107 - 114.
  22. Wald, I., Benthin, C., Wagner, M., and Slusallek, P. (2001). Interactive rendering with coherent ray tracing. In Computer Graphics Forum (Proceedings of Eurographics'01), volume 20, pages 153-164.
  23. Wald, I., Gribble, C. P., Boulos, S., and Kensler, A. (2007). SIMD Ray Stream Tracing - SIMD Ray Traversal with Generalized Ray Packets and On-the-fly Re-Ordering. Technical Report UUSCI-2007-012.
  24. Wald, I. and Slusallek, P. (2001). State of the art in interactive ray tracing. In State of the Art Reports, EUROGRAPHICS 2001, pages 21-42.
  25. Zlatuska, M. and Havran, V. (2010). Ray tracing on a GPU with CUDA - comparative study of three algorithms. In Proceedings of WSCG'2010, communication papers, pages 69-76.
  26. Zomaya, A. and Kazman, R. (1999). Handbook of Algorithms and Theory of Computation, chapter Simulated Annealing Techniques, pages 37.1-33.19. CRC Press.
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Paper Citation


in Harvard Style

Torres R., J. Martín P. and Gavilanes A. (2011). TRAVERSING A BVH CUT TO EXPLOIT RAY COHERENCE . In Proceedings of the International Conference on Computer Graphics Theory and Applications - Volume 1: GRAPP, (VISIGRAPP 2011) ISBN 978-989-8425-45-4, pages 140-150. DOI: 10.5220/0003363401400150


in Bibtex Style

@conference{grapp11,
author={R. Torres and P. J. Martín and A. Gavilanes},
title={TRAVERSING A BVH CUT TO EXPLOIT RAY COHERENCE},
booktitle={Proceedings of the International Conference on Computer Graphics Theory and Applications - Volume 1: GRAPP, (VISIGRAPP 2011)},
year={2011},
pages={140-150},
publisher={SciTePress},
organization={INSTICC},
doi={10.5220/0003363401400150},
isbn={978-989-8425-45-4},
}


in EndNote Style

TY - CONF
JO - Proceedings of the International Conference on Computer Graphics Theory and Applications - Volume 1: GRAPP, (VISIGRAPP 2011)
TI - TRAVERSING A BVH CUT TO EXPLOIT RAY COHERENCE
SN - 978-989-8425-45-4
AU - Torres R.
AU - J. Martín P.
AU - Gavilanes A.
PY - 2011
SP - 140
EP - 150
DO - 10.5220/0003363401400150