All Frequency Direct Illumination Using Visibility Correspondence Generated With Spherical Voronoi Diagrams

Vectorized visibility is a powerful visibility representation for rendering direct illumination with all frequency quality. However, the existing rendering method requires the visibility functions to be synthesized three times, followed with three radiance evaluation, for each triangle of the 3D model. We propose an alternative method to enhance vectorized visibility, such that we can directly interpolate the vectorized visibility, and therefore, reduce the computation bottleneck, i.e. the radiance evaluation, to just once. To facilitate the interpolation, we need to generate the correspondence among the three sampled visibility functions for each triangular patch. This paper uses spherical Voronoi diagram as a tool to conduct a preliminary correspondence generation, instead of doing brute force search. Additional treatments are also implemented to ensure that the interpolated visibility functions have smooth transition across the 3D model. With our method, we have more flexibility to manipulate the visibility functions in the favour of rendering speed and render the all frequency direct illumination twice as fast as the previous method.