Progressive transient photon beams

1Universidad de Zaragoza, I3A 2Dartmouth College

In Computer Graphics Forum, 2019

The SOCCER scene (steady-state render on the right) features complex volumetric caustics due to multiple reflections and refractions off smooth dielectrics inside the medium. We are able to efficiently render the transient light transport (left sequence) by formulating a progressive, transient form of photon beam density estimation which provably eliminates error while working within a finite memory budget.


In this work, we introduce a novel algorithm for transient rendering in participating media. Our method is consistent, robust and is able to generate animations of time-resolved light transport featuring complex caustic light paths in media. We base our method on the observation that the spatial continuity provides an increased coverage of the temporal domain, and generalize photon beams to transient-state. We extend stead-state photon beam radiance estimates to include the temporal domain. Then, we develop a progressive variant of our approach which provably converges to the correct solution using finite memory by averaging independent realizations of the estimates with progressively reduced kernel bandwidths. We derive the optimal convergence rates accounting for space and time kernels, and demonstrate our method against previous consistent transient rendering methods for participating media.



Video (full-quality)


Julio Marco, Ibón Guillén, Wojciech Jarosz, Diego Gutierrez, Adrian Jarabo. Progressive transient photon beams. Computer Graphics Forum, 38(6):19–30, September 2019.
    author  = {Marco, Julio and Guill\'en, Ib\'on and Jarosz, Wojciech and Gutierrez, Diego and Jarabo, Adrian},
    title   = {Progressive transient photon beams},
    journal = {Computer Graphics Forum},
    volume  = {38},
    number  = {6},
    year    = {2019},
    month   = sep,
    pages   = {19--30},
    doi     = {10/gfvr9w}
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