High-Performance Graphics 2017

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https://diglib.eg.org/handle/10.2312/2631971

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Browsing High-Performance Graphics 2017 by Subject "bounding volume hierarchy"

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    Accelerated Single Ray Tracing for Wide Vector Units
    (ACM, 2017) Fuetterling, Valentin; Lojewski, Carsten; Pfreundt, Franz-Josef; Hamann, Bernd; Ebert, Achim; Vlastimil Havran and Karthik Vaiyanathan
    Utilizing the vector units of current processors for ray tracing single rays through Bounding Volume Hierarchies has been accomplished by increasing the branching factor of the acceleration structure to match the vector width. A high branching factor allows vectorized bounding box tests but requires a complex control flow for the calculation of a front-to-back traversal order. We propose a novel algorithm for single rays entirely based on vector operations that performs a complete traversal iteration in constant time, ideally suited for current and future micro architectures featuring wide vector units. In addition we use our single ray technique as a building block to construct a fast packet traversal for coherent rays. We validate our algorithms with implementations utilizing the AVX2 and AVX-512 instruction sets and demonstrate significant performance gains over state-of-the-art solutions.
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    Extended Morton Codes for High Performance Bounding Volume Hierarchy Construction
    (ACM, 2017) Vinkler, Marek; Bittner, Jiří; Havran, Vlastimil; Vlastimil Havran and Karthik Vaiyanathan
    We propose an extension to the Morton codes used for spatial sorting of scene primitives. e extended Morton codes increase the coherency of the clusters resulting from the object sorting and work be er for non-uniform distribution of scene primitives. In particular, our codes are enhanced by encoding the size of the objects, applying adaptive ordering of the code bits, and using variable bit counts for di erent dimensions. We use these codes for constructing Bounding Volume Hierarchies (BVH) and show that the extended Morton code leads to higher quality BVH, particularly for the fastest available BVH build algorithms that heavily rely on spatial coherence of Morton code sorting. In turn, our method allows to achieve up to 54% improvement in the BVH quality especially for scenes with a non-uniform spatial extent and varying object sizes. Our method is easy to implement into any Morton code based build algorithm as it involves only a modi cation of the Morton code computation step.
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    Improved Two-Level BVHs Using Partial Re-Braiding
    (ACM, 2017) Benthin, Carsten; Woop, Sven; Afra, Attila T.; Wald, Ingo; Vlastimil Havran and Karthik Vaiyanathan
    We propose a novel approach for improving the quality of two-level BVHs (i.e., a two-level data structure that uses a top-level BVH built over second-level object BVHs). After building an individual, high-quality BVH for each object, our new top-level BVH build approach selectively re-braids (opens and merges) object BVHs during the build process to reduce overlap and improve SAH quality. We demonstrate that compared to the two main state-of-the-art techniques-brute-force re-construction of a single, flat BVH; and building a traditional two-level BVH over objects, respectively-the proposed approach achieves build times significantly faster than the former, while simultaneously yielding traversal performance that is much higher than the latter.