Spatiotemporal reservoir resampling for real-time ray
tracing with dynamic direct lighting
Benedikt Bitterli Chris Wyman Matt Pharr Peter Shirley Aaron Lefohn Wojciech Jarosz
In ACM Transactions on Graphics (Proceedings of SIGGRAPH), 2020
Two complex scenes ray traced with direct lighting from many dynamic lights. (Left) A still from the Zero Day video with 11,000 dynamic emissive triangles. (Right) A view of one ride in an Amusement Park scene containing 3.4 million dynamic emissive triangles. Both images show three methods running in equal time on a modern GPU, from left to right: Moreau et al. [2019]’s efficient light-sampling BVH, our new unbiased estimator, and our new biased estimator. The Zero Day image is rendered in 15 ms and Amusement Park in 50 ms, both at 1920×1080 resolution. Zero Day ©beeple, Pirate Ship ©sema edis
Abstract
Efficiently rendering direct lighting from millions of dynamic light sources using Monte Carlo integration remains a challenging problem, even for off-line rendering systems. We introduce a new algorithm—ReSTIR—that renders such lighting interactively, at high quality, and without needing to maintain complex data structures. We repeatedly resample a set of candidate light samples and apply further spatial and temporal resampling to leverage information from relevant nearby samples. We derive an unbiased Monte Carlo estimator for this approach, and show that it achieves equal-error 6×-60× faster than state-of-the-art methods. A biased estimator reduces noise further and is 35×-65× faster, at the cost of some energy loss. We implemented our approach on the GPU, rendering complex scenes containing up to 3.4 million dynamic, emissive triangles in under 50 ms per frame while tracing at most 8 rays per pixel.
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