Normal mapping for precomputed radiance transfer

Abstract

Normal mapping is a variant of bump mapping that is commonly used in computer games. It models complex surface variations by explicitly storing a surface normal in a texture map. However, it has not been used with precomputed radiance transfer (PRT), a technique for modeling an object's response to a parameterized model of lighting, which enables interactive rendering of complex global illumination effects such as soft shadows and interreflections. This paper presents several techniques that effectively combine normal mapping and precomputed radiance transfer for rigid objects. In particular, it investigates representing the convolved radiance function in various bases and borrowing concepts from the separable decomposition of BRDF's.