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Abstract

Photon tracing and density estimation are well established
techniques in global illumination computation and rendering of
high-quality animation sequences. Using traditional density estimation
techniques
it is difficult to remove stochastic noise inherent for photon-based
methods while avoiding overblurring lighting details.
In this paper we investigate the use of bilateral filtering
for lighting reconstruction based on the local density of photon hit points.
Bilateral filtering is applied in spatio-temporal domain and
provides control over the level-of-details in reconstructed lighting.
All changes of lighting below this level are treated as
stochastic noise and are suppressed. Bilateral
filtering proves to be efficient in preserving sharp features
in lighting which is in particular important for high-quality caustic
reconstruction. Also, flickering
between subsequent animation frames is substantially reduced
due to extending bilateral filtering into temporal domain.