Rendering of inhomogeneous volumes using perturbation functions

A method for rendering inhomogeneous volumes using perturbation functions is presented. An approach is proposed for sampling light transmission paths in heterogeneous media. At the initial stage of calculations, light transmission paths are constructed in a closed form. Then the heterogeneous component is averaged by adding a formal medium. Next, the path-tracking algorithm is used. Due to this, there is no need to calculate strict boundaries of the attenuation function. Samples in the closed-form light transmission path and the averaged medium are made separately. This minimizes the costly calculations of collision coefficients that change when traversing space.