Stenciled Volumetric Ambient Occlusion

Abstract

Screen-space Ambient Occlusion (AO) is commonly used in games to calculate the exposure of each pixel to ambient lighting with the help of a depth buffer. Due to its screen-space nature, it suffers from several artifacts if depth information is missing. Stochastic-Depth AO [VSE21] was introduced to minimize the probability of missing depth information, however, rendering a full stochastic depth map can be very expensive. We introduce a novel rendering pipeline for AO that divides the AO pass into two phases, which allows us to create a stochastic depth map for only a subset of pixels, in order to decrease the rendering time drastically. We also introduce a variant that replaces the stochastic depth map with ray tracing that has competitive performance. Our AO variants are based on Volumetric AO [LS10], which produces similar effects compared to the commonly used horizon-based AO [BSD08], but requires less texture samples to produce good results.