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Abstract:
We present a novel framework for efficiently computing the indirect
illumination in diffuse and moderately glossy scenes using density estimation
techniques.
A vast majority of existing global illumination approaches either quickly
computes an approximate solution, which may not be adequate for previews, or
performs a much more time-consuming computation to obtain high-quality results
for the indirect illumination. Our method improves photon density estimation,
which is an approximate solution, and leads to significantly better visual
quality in particular for complex geometry, while only slightly increasing the
computation time. We perform direct splatting of photon rays, which allows us
to use simpler search data structures. Our novel lighting computation is
derived from basic radiometric theory and requires only small changes to
existing photon splatting approaches.
Since our density estimation is carried out in ray space rather than on
surfaces, as in the commonly used photon mapping algorithm, the results are
more robust against geometrically incurred sources of bias. This holds also in
combination with final gathering where photon mapping often overestimates the
illumination near concave geometric features. In addition, we show that our
splatting technique can be extended to handle moderately glossy surfaces and
can be combined with traditional irradiance caching for sparse sampling and
filtering in image space.
