PSAO: Point-Based Split Rendering for Ambient Occlusion

Abstract

Recent advances in graphics hardware have enabled ray tracing to produce high-quality ambient occlusion (AO) in real-time, which is not plagued by the artifacts typically found in real-time screen-space approaches. However, the high computational cost of ray tracing remains a significant hurdle for low-power devices like standalone VR headsets or smartphones. To address this challenge, inspired by point-based global illumination and texture-space split rendering, we propose point-based split ambient occlusion (PSAO), a novel split-rendering system that streams points sparsely from server to client. PSAO first evenly distributes points across the scene, and then subsequently only transmits points that changed more than a given threshold, using an efficient hash grid to blend neighboring points for the final compositing pass on the client. PSAO outperforms recent texture-space shading approaches in terms of quality and required network bit rate, while demonstrating performance similar to commonly used lower-quality screen-space approaches. Our point-based split rendering representation lends itself to highly compressible signals such as AO and is scalable towards quality or bandwidth requirements by adjusting the number of points in the scene.