This article presents the density estimation framework for generating
view-independent global illumination solutions. It works by probabilis
tically simulating the light flow in an environment with light particl
es that trace random walks originating at luminaires and then using st
atistical density estimation techniques to reconstruct the lighting on
each surface. By splitting the computation into separate transport an
d reconstruction stages, we gain many advantages including reduced mem
ory usage, the ability to simulate nondiffuse transport, and natural p
arallelism. Solutions to several theoretical and practical difficultie
s in implementing this framework are also described. Light sources tha
t vary spectrally and directionally are integrated into a spectral par
ticle tracer using nonuniform rejection. A new local linear density es
timation technique eliminates boundary bias and extends to arbitrary p
olygons. A mesh decimation algorithm with perceptual calibration is in
troduced to simplify the Gouraud-shaded representation of the solution
for interactive display.