Scalable ambient obscurance

This paper presents a set of architecture-aware performance and integration improvements for a recent screenspace ambient obscurance algorithm. These improvements collectively produce a 7 x performance increase at 2560 x1600, generalize the algorithm to both forward and deferred renderers, and eliminate the radius- and scene-dependence of the previous algorithm to provide a hard real-time guarantee of fixed execution time. The optimizations build on three strategies: pre-filter the depth buffer to maximize memory hierarchy efficiency; reduce total bandwidth by carefully reconstructing positions and normals at high precision from a depth buffer; and exploit low-level intra- and inter-thread techniques for parallel, floating-point architectures.