Interactive Stable Ray Tracing

Abstract

Interactive ray tracing applications running on commodity hard- ware can su er from objectionable temporal artifacts due to a low sample count. We introduce stable ray tracing, a technique that improves temporal stability without the over-blurring and ghosting artifacts typical of temporal post-processing lters. Our technique is based on sample reprojection and explicit hole lling, rather than relying on hole- lling heuristics that can compromise image quality. We make reprojection practical in an interactive ray tracing context through the use of a super-resolution bitmask to estimate screen space sample density. We show signi cantly improved temporal stability as compared with supersampling and an existing reprojec- tion techniques. We also investigate the performance and image quality di erences between our technique and temporal antialias- ing, which typically incurs a signi cant amount of blur. Finally, we demonstrate the bene ts of stable ray tracing by combining it with progressive path tracing of indirect illumination.