Participating media render – running

Images for Eurographics 2018. Abstract of the paper: Rendering inhomogeneous participating media requires a lot of volume samples since the extinction coefficient needs to be fetched from the volume along light paths. Ray marching makes small steps and generates regular samples, which is time consuming and leads to biased algorithms. Woodcock-like approaches use analytic sampling and a random rejection scheme guaranteeing that the expectations will be the same as in the original model. These models and the application of control
variates for the extinction have been successful to compute transmittance and single scattering but were not fully exploited
in multiple scattering simulation. Our paper attacks the multiple scattering problem in heterogeneous media and presents an
algorithm that modifies the light–medium interaction model to allow the use of simple analytic formulae while preserving the
correct expected values. Additionally, the model transformation reduces the variance of the estimates with respect to the direct
simulation with the help of Rao-Blackwellization and control variates applied both for the extinction coefficient and the incident radiance.

Project owner:
Dr. Magdics Milán (Irányítástechnika és Informatika Tanszék)
Irányítástechnika és Informatika Tanszék (VIK-IIT)