Interactive Ray-Traced Scene Editing Using Ray Segment Trees

Abstract

This paper presents a ray tracer that facilitates near-interactive scene editing with incremental rendering; the user can edit the scene both by manip-ulating objects and by changing the viewpoint. Our system uses object-space radiance interpolants to accelerate ray tracing by approximating radiance, while bounding error. We introduce a new hierarchical data structure, the ray seg-ment tree (RST), which tracks the dependencies of radiance interpolants on re-gions of world space. When the scene is edited, affected interpolants are rapidly identified— typically in 0.1 seconds—by traversing these ray segment trees. The affected interpolants are updated and used to re-render the scene with a 3 to 4¢ speedup over the base ray tracer, even when the viewpoint is changed. Although the system does no pre-processing, performance is better than for the base ray tracer even on the first rendered frame.