Hybrid Ambient Occlusion

Abstract

Ambient occlusion captures a subset of global illumination effects, by computing for each point of the surface the amount of incoming light from all directions and considering potential occlusion by neighboring geometry. We introduce an approach to ambient occlusion combining object and image space techniques in a deferred shading context. It is composed of three key steps: an on-the-fly voxelization of the scene, an occlusion sampling based on this voxelization and a bilateral filtering of this sampling in screen space. The result are smoothly varying ambient terms in occluded areas at interactive frame rates without any precomputation. In particular, all computations are performed dynamically on the GPU while eliminating the problem of screen-space methods, namely ignoring geometry that is not rasterized into the Z-buffer.