Real-time ray-traced ambient occlusion of complex scenes using spatial hashing

Abstract

Ambient occlusion is often approximated in real-time using screen-space techniques, leading to visible artifacts. Raytracing provides a unique way to increase the rendering fidelity by accurately sampling the distance to the surrounding objects, but it introduces sampling noise. We propose a real-time ray-traced ambient occlusion technique in which noise is filtered in world space. Using extended spatial hashing for efficient storage, multiresolution AO evaluation and ad-hoc filtering, we demonstrate the usability of our technique as a production feature usable in CAD viewports with scenes comprising hundreds of millions of polygons.