This tutorial explains how global illumination rendering methods can be implemented on Shader Model 3.0 GPUs. These algorithms do not follow the conventional local illumination model of DirectX/OpenGL pipelines, but require global geometric or illumination information when shading a point. In addition to the theory and state of the art of these approaches, the tutorial goes into the details of a few algorithms, including mirror reflection, refraction, caustics, diffuse/glossy indirect illumination, precomputation-aided global illumination for surface and volumetric models, obscurances and tone mapping, also giving their GPU implementation in HLSL or Cg language. (Laszlo Szirmay-Kalos, Laszlo Scecsi, Mateu Sbert: GPUGI: Global Illumination Effects on the GPU. Eurographics 2006 Tutorial.)

Fantasy Lab, a game developer located in the San Francisco Bay area, has announced its new game engine, which includes support for real-time global illumination and displacement-mapped subdivision surfaces. Videos on the company’s website show global illumination on an animated subdivision-surface-based character. The global illumination solution for the videos is calculated in 3.3 milliseconds per frame (300 frames per second) on an NVIDIA GeForce Go 7900 GTX (a laptop GPU).

The irradiance caching algorithm is commonly used for fast global illumination since it provides high-quality rendering in a reasonable time. However this algorithm relies on a spatial data structure along with complex algorithms. This central and permanently modified data structure prevents this algorithm from being easily implemented on GPUs. This paper proposes a novel approach to global illumination using irradiance and radiance cache: the Radiance Cache Splatting. This method directly meets the processing constraints of graphics hardware since it avoids the need of complex data structure and algorithms. Moreover, the rendering quality remains identical to classical irradiance and radiance caching. This work will be presented at the Eurographics Symposium on Rendering 2005, and during SIGGRAPH 2005 sketches. (Radiance Cache Splatting: A GPU-Friendly GLobal Illumination Algorithm. Pascal Gautron, Jaroslav Krivanek, Kadi Bouatouch, Sumanta Pattanaik. Proceedings of Eurographics Symposium on Rendering 2005)

Efficient and visually compelling reproduction of effects due to multiple scattering in participating media remains one of the most difficult tasks in computer graphics. Although several fast techniques were recently developed, most of them work only for special types of media (for example, uniform or sufficiently dense) or require extensive precomputation. In this paper we present a lighting model for the general case of inhomogeneous medium and demonstrate its implementation on programmable graphics hardware. It is capable of producing high quality imagery at interactive frame rates with only mild assumptions about medium scattering properties and a moderate amount of simple precomputation. (A Lighting Model for General Participating Media. Kyle Hegeman, Michael Ashikhmin and Simon Premoze. Accepted for publication. Proceedings of ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games, April 2005.)

This dissertation by Mangesh Nijasure of University of Central Florida presents a system for computing plausible global illumination solutions for dynamic environments in real time on programmable graphics processors (GPUs). The dissertation describes a progressive global illumination algorithm to simulate multiple bounces of light on the surfaces of synthetic scenes. The entire algorithm runs on an ATI Radeon 9800 using vertex and fragment shaders, and computes global illumination solutions for reasonably complex scenes with moving objects and moving lights in real time. (Real-time Global Illumination on GPU, Mangesh Nijasure. MS Thesis, Fall 2003)

This report by Coombe et al. describes a technique for computing radiosity, including an adaptive subdivision of the model, using graphics hardware. The technique uses floating point textures and fragment programs to perform progressive refinement using a novel implementation of hemicube radiosity on the GPU. (Radiosity on Graphics Hardware. Greg Coombe, Mark J. Harris, Anselmo Lastra. UNC TR03-020. June, 2003.)

This paper by Purcell et al. presents a photon mapping algorithm that runs entirely on the GPU. The paper presents details for tracing photons, building the photon map, and computing the radiance estimate at each pixel using a k-nearest neighbor search.(Photon Mapping on Programmable Graphics Hardware. Timothy J. Purcell, Craig Donner, Mike Cammarano, Henrik Wann Jensen, and Pat Hanrahan. Proceedings of Graphics Hardware 2003, July 2003.)

This paper by Carr et al. describes a method for computing subsurface scattering on the GPU. They use a multi-resolution meshed atlas and modern GPU programmability to devise a real-time GPU algorithm that can render semi-transparent objects with diffuse subsurface-scattered illumination under dynamic lighting and viewing conditions. (GPU Algorithms for Radiosity and Subsurface Scattering. Nathan A. Carr, Jesse D. Hall, and John C. Hart. Proceedings of Graphics Hardware 2003, July 2003.)