An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson...
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![Page 1: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/1.jpg)
An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing
Jefferson Amstutz (SURVICE)Johannes Guenther (Intel)
Ingo Wald (Intel)Christiaan Gribble (SURVICE)
![Page 2: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/2.jpg)
The Multi-Hit Problem
• Objective: find more than one (possibly all) hit point along the ray [Gribble et al. ’13]– Ray t-distance sorted order– No ray re-launch
![Page 3: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/3.jpg)
Overlapping Geometry
![Page 4: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/4.jpg)
Overlapping Geometry
![Page 5: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/5.jpg)
Bounding Volume Hierarchies
• BVHs have been one of the premier structures for accelerating rays– Fast builds– Fast traversal
• Node overlaps create issues for doing multi-hit ray tracing
![Page 6: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/6.jpg)
Spatial vs. Object Partitioning
![Page 7: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/7.jpg)
Existing BVH Traversal solutions
• Many state-of-the-art implementations for both CPUs and GPUs– Embree (Intel x86, MIC)– Optix (NVIDIA GPUs)
• Intersection callbacks– Client application injects logic to “accept” or
“reject” individual hit points
![Page 8: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/8.jpg)
Traversal Techniques
• Must be all-hit ray traversal– Cannot *guarantee* first N hits with first/any hit trav.
• Sorting hit points– Sort during ray traversal (progressive)– Sort after hit points gathered (post traversal)
• Hit point data layout– Array of Structures (AoS)
• Scalar sorting
– Structure of Arrays (SoA)• Vectorized sorting
![Page 9: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/9.jpg)
Results (SIMD Sorting Efficiency)
![Page 10: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/10.jpg)
Results (hairball)
![Page 11: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/11.jpg)
Results (pplant)
![Page 12: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/12.jpg)
Results (truck)
![Page 13: An Evaluation of Existing BVH Traversal Algorithms for Efficient Multi-Hit Ray Tracing Jefferson Amstutz (SURVICE) Johannes Guenther (Intel) Ingo Wald.](https://reader035.fdocuments.us/reader035/viewer/2022062517/56649ee65503460f94bf6184/html5/thumbnails/13.jpg)
Future Work
• Memory allocation strategies for variable hit point buffers– Caching strategies for performance– Reduce/prevent hit point memory waste
• Multi-hit traversal algorithms for BVHs