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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. Many existing global illumination
approaches either quickly compute
an overly approximate solution or perform an orders of magnitude slower
computation to obtain high-quality
results for the indirect illumination. The proposed method improves photon
density estimation 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. 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 photon 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.