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Abstract

Visibility computations are the most time-consuming part of
global illumination algorithms. The cost is amplified by the
fact that quite often identical or similar information is
recomputed multiple times. In particular this is the case when
multiple images of the same scene are to be generated under
varying lighting conditions and/or viewpoints. But even for a
single image with static illumination, the computations could be
accelerated by reusing visibility information for many different
light paths.

In this paper we describe a general method of precomputing,
storing, and reusing visibility information for light transport
in a number of different types of scenes. In particular, we
consider general parametric surfaces, triangle meshes without a
global parameterization, and participating media.

We also reorder the light transport in such a way that the
visibility information is accessed in structured memory access
patterns. This yields a method that is well suited for SIMD-style
parallelization of the light transport, and can efficiently be
implemented both in software and using graphics hardware. We
finally demonstrate applications of the method to highly
efficient precomputation of BRDFs, bidirectional texture
functions, light fields, as well as near-interactive volume
lighting.