Visibility Filtering for Producing Indirect Illumination

Abstract

Indirect illumination is one of the most visually significant effects for a synthesized image. In order to render such effects at interactive rates, it is important to resolve the visibility between surfaces efficiently. In this work, we propose to approximate visibility by representing the scene through point proxies and hash them into voxels. The indirect illumination is then rendered in two stages. First, we cast sparse shadow rays to march and collect visible voxels for each low-resolution deferred pixel. The list of visible voxels are then processed using the proposed Visibility Filter (VF) to collect voxels missed from the first stage. Afterward, we properly weight the visible voxels as light sources to produce the full resolution image. Our method runs at interactive rates at 1.3 fps to 2.3 fps on GPUs with pleasing visual quality, in particular for glossy reflections.