Using Half-Precision Floating-Point Numbers for Storing Bounding Volume Hierarchies

Matias Koskela, Timo Viitanen, Pekka Jääskeläinen, Jarmo Henrik Takala, Ken Cameron

    Research output: Chapter in Book/Report/Conference proceedingConference contributionProfessional

    Abstract

    Bounding volume hierarchies, which are commonly used to speed up ray tracing, are heavily accessed during ray traversal. Reducing the memory footprint for the bounding volume hierarchies leads to a better cache hit ratio and, therefore, faster ray tracing. This paper examines an approach of using 16-bit half-precision floating-point numbers to store bounding volume hierarchy inner nodes. Compared to prior work on BVH node compression, which uses integers, floats are interesting because of their dynamic range. Compared to single-precision, half-precision inner nodes have half
    memory footprint and, therefore, they save an average of 1.7% total power. This comes with the small conversion cost overhead, average of 2.5% more ray-box intersection tests and average of 15% more ray-triangle intersection tests. If half floats are used hierarchically, rather than simply storing world coordinates as halfs, roughly the same accuracy is achieved as with single-precision. This eliminates the additional intersection tests, but it requires additional computations to obtain the world coordinates during traversal.
    Original languageEnglish
    Title of host publicationProceedings of the 32nd Computer Graphics International Conference
    Publication statusPublished - 2015
    Publication typeD3 Professional conference proceedings
    EventComputer Graphics International Conference -
    Duration: 1 Jan 2000 → …

    Conference

    ConferenceComputer Graphics International Conference
    Period1/01/00 → …

    Keywords

    • Ray Tracing
    • Half-Precision Floating-Point
    • Bounding Volume Hierarchy

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