Accelerating diffuse indirect lighting with irradiance caching

Abstract

Diffuse indirect lighting is a subset of global illumination that can be quite computationally expensive to compute. While Path Tracing is the standard for computing it, several techniques have been proposed to accelerate its computation, one of which being Irradiance Caching. In order to investigate whether the gain in performance by the irradiance cache is feasible in terms of change in quality, a multithreaded C++ implementation was developed and integrated into a custom hybrid Path-Tracing and Distributed Ray-tracing solution. The solution was evaluated using a set of test scenes and a number of sample counts, of which the results were compared to that of a reference path tracer. The two solutions are compared based on performance metrics such as render time, and quality metrics such as SSIM and PSNR. Based on the results obtained, it was concluded that the solution offers a significant gain in performance, and is deemed appropriate to replace path tracing in cases where accuracy is not the top priority. However, when accuracy and unbiased rendering are the top priority, the more traditional method of path tracing would be more suitable.