Diffuse global illumination in particle spaces

Abstract

Despite substantial efforts in recent years to accelerate rendering methods, the traditional method, based on a combination of recursive ray tracing (RT), photon mapping (PM), and final gathering (FG), is still regarded as computationally intensive. In this paper, we propose a practical ray tracing model that can be readily implemented on a graphics processing unit (GPU) to provide high-speed generation of global illumination, whose quality is comparable to that generated through the traditional time-consuming RT/PM/FG rendering method. Our method employs two particle spaces to generate computationally intensive diffuse interreflection more efficiently. The complexity of light transport within a scene is simulated in one particle space by using indirect light scattering and gathering operations. The calculation that estimates the reflected radiance caused by diffuse interreflection is optimized by using a second particle space, where only the radiance required for final rendering can be rapidly approximated, based on the simulated light flux in the first particle space. We present several example scenes to demonstrate that our ray tracing scheme enables the use of a rendering pipeline that fully exploits the computing architecture of current manycore processors to reproduce effective high-quality global illumination.