The beam radiance estimate for volumetric photon mapping

1UC San Diego

In Computer Graphics Forum (Proceedings of Eurographics), 2008

Standard volumetric photon mapping (top) estimates in-scattered radiance by repeatedly finding photons at points along camera rays during ray marching. We introduce the beam radiance estimate (bottom) which finds all photons contributing to an entire camera ray in one query without the need for ray marching. This leads to significantly higher quality at equal render time.


We present a new method for efficiently simulating the scattering of light within participating media. Using a theoretical reformulation of volumetric photon mapping, we develop a novel photon gathering technique for participating media. Traditional volumetric photon mapping samples the in-scattered radiance at numerous points along the length of a single ray by performing costly range queries within the photon map. Our technique replaces these multiple point-queries with a single beam-query, which explicitly gathers all photons along the length of an entire ray. These photons are used to estimate the accumulated in-scattered radiance arriving from a particular direction and need to be gathered only once per ray. Our method handles both fixed and adaptive kernels, is faster than regular volumetric photon mapping, and produces images with less noise.



Wojciech Jarosz, Matthias Zwicker, Henrik Wann Jensen. The beam radiance estimate for volumetric photon mapping. Computer Graphics Forum (Proceedings of Eurographics), 27(2):557–566, April 2008.
    author  = {Jarosz, Wojciech and Zwicker, Matthias and Jensen, Henrik Wann},
    title   = {The Beam Radiance Estimate for Volumetric Photon Mapping},
    journal = {Computer Graphics Forum (Proceedings of Eurographics)},
    volume  = {27},
    number  = {2},
    year    = {2008},
    month   = apr,
    pages   = {557--566},
    doi     = {10/bjsfsx}
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