Fast Approximation of Multiple Scattering in Inhomogeneous Participating Media

Abstract

This paper presents a fast approximation for the solution of the radiative transfer equation in inhomogeneous participating media. This scheme traces rays from the point light creating spherical wavefronts. While we march on a particular ray, we assume that other rays find similar material properties, which allows the solution of the diffusion equation for this ray. The proposed approximation of the scattered component can be computed in parallel with obtaining the direct term at practically no additional cost. The approximation may be used for direct visualization, an initial guess for an iterative solution, or for the main part of a Monte Carlo solution.