Precomputed Visibility Cuts for
Interactive Relighting with Dynamic BRDFs
University of Massachusetts Amherst
Pacific Graphics 2007
Interactive Relighting with Dynamic BRDFs
Oskar Akerlund | Mattias Unger | Rui Wang |
Pacific Graphics 2007
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Abstract
This paper presents a novel PRT-based method that uses
precomputed visibility cuts for interactive view-dependent
relighting under all-frequency environment maps and arbitrary
BRDFs. Our method is inspired by Lightcuts
and we parameterize distant environment lighting onto uniformly
distributed sample points on the unit sphere. Using
a binary tree structure of the sample points, we precompute
and approximate each vertex's visibility function
into clusters that we call the precomputed visibility cuts.
These cuts are computed with bounded approximation error
and confined cluster size using iterative refinement. At runtime,
a GPU-based relighting algorithm quickly computes
the view-dependent shading color by accessing a dynamically
built cluster of the lighting, the precomputed visibility
cuts, and a direct evaluation of the dynamic BRDF using
the average direction represented by each lighting cluster.
Compared to existing PRT techniques, our method guarantees
uniform sampling of the lighting, requires no precomputed
BRDF data, and can be easily extended to handle
one-bounce glossy indirect transfer effects in real-time.
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