The Backward Photon Mapping for the Realistic Image Rendering

The current paper is devoted to the methods of the realistic rendering methods based on the bidirectional stochastic ray tracing with photon maps. The research of the backward photon mapping method to account for both caustics and indirect illumination is presented. By using the backward photon maps authors reduced the amount of data that should be stored in the photon maps that allowed to speed up the process of the indirect luminance calculation. Methods used for constructing a tree of backward photon maps and methods of efficient parallelization used in algorithms of accumulation and forming the backward photon maps along with tracing forward and back-ward rays in the rendering process are considered. Methods to estimate the attained luminance error both for single image pixels and for the entire image with the designed rendering method are presented. The rendering results obtained with the use of the developed methods and algorithms are presented.