Accelerated Bounded-Error Ray Tracing Using Per-Surface Radiance Interpolants

Ray tracing, which computes radiance, is usually regarded as an off-line rendering algorithm that is too slow for interactive use. In this paper, we present a system that uses per-surface four-dimensional interpolants to approximate radiance, while providing guaranteed error bounds. Our system exploits object-space, ray-space, image-space and temporal coherence to accelerate ray tracing. Our system explicitly decouples the two primary operations of a ray tracer --- shading and visibility determination at each pixel --- and accelerates each of them independently. Shading is accelerated by lazily collecting 4D radiance samples, and quadrilinearly interpolating them to approximate radiance. Interpolation error does not exceed a user-specified bound ffl that the user can vary to trade performance for quality. Error is bounded by adaptive sampling at discontinuities and radiance non-linearities. Visibility determination at a pixel is also accelerated by reprojecting interpolants as the user..