Dynamic Many-Light Sampling for Real-Time Ray Tracing

Pierre Moreau, Matt Pharr, Petrik Clarberg

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceedingpeer-review


Monte Carlo ray tracing offers the capability of rendering scenes with large numbers of area light sources---lights can be sampled stochastically and shadowing can be accounted for by tracing rays, rather than using shadow maps or other rasterization-based techniques that do not scale to many lights or work well with area lights. Current GPUs only afford the capability of tracing a few rays per pixel at real-time frame rates, making it necessary to focus sampling on important light sources. While state-of-the-art algorithms for offline rendering build hierarchical data structures over the light sources that enable sampling them according to their importance, they lack efficient support for dynamic scenes. We present a new algorithm for maintaining hierarchical light sampling data structures targeting real-time rendering. Our approach is based on a two-level BVH hierarchy that reduces the cost of partial hierarchy updates. Performance is further improved by updating lower-level BVHs via refitting, maintaining their original topology. We show that this approach can give error within 6% of recreating the entire hierarchy from scratch at each frame, while being two orders of magnitude faster, requiring less than 1 ms per frame for hierarchy updates for a scene with thousands of moving light sources on a modern GPU. Further, we show that with spatiotemporal filtering, our approach allows complex scenes with thousands of lights to be rendered with ray-traced shadows in 16.1 ms per frame.
Original languageEnglish
Title of host publicationHigh-Performance Graphics 2019 - Short Papers
EditorsMarkus Steinberger, Tim Foley
PublisherEurographics - European Association for Computer Graphics
Number of pages6
ISBN (Electronic)978-3-03868-092-5
Publication statusPublished - 2019
EventHigh-Performance Graphics, 2019 - University of Strasbourg, Strasbourg, France
Duration: 2019 Jul 82019 Jul 10


ConferenceHigh-Performance Graphics, 2019
Internet address

Subject classification (UKÄ)

  • Computer Science


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