Accelerating Real-Time Shading with Reverse Reprojection Caching

Abstract

Evaluating pixel shaders consumes a growing share of the computational budget for real-time applications. However, the significant temporal coherence in visible surface regions, lighting conditions, and camera location allows reusing computationally-intensive shading calculations between frames to achieve significant performance improvements at little degradation in visual quality. This paper investigates a caching scheme based on reverse reprojection which allows pixel shaders to store and reuse calculations performed at visible surface points. We provide guidelines to help programmers select appropriate values to cache and present several policies for keeping cached entries up-to-date. Our results confirm this approach offers substantial performance gains for many common real-time effects, including precomputed global lighting effects, stereoscopic rendering, motion blur, depth of field, and shadow mapping.