Abstract: In this paper, we present two optimization techniques to light and render volumetric data of inhomogeneous participating media. Both are independent of the lighting model selected. We use an implementation of the ray marching algorithm to approximate the Radiance Transfer Equation. The system can calculate single scattering in time-varying isotropic participating media with the incident field being modeled as a high dynamic range (HDR) environment map. We can use dynamic lighting (with certain restrictions) and free camera movement without using any precomputations while achieving interactive frame rates.