All-Frequency Relighting of Glossy Objects
ACM Transactions on Graphics 25(2), 2006
Rui Wang, John Tran, David Luebke
Abstract
We present a technique for interactive rendering of glossy objects in complex and dynamic lighting environments that captures interreflections and all-frequency shadows. Our system is based
on precomputed radiance transfer and separable BRDF approximation. We factor glossy BRDFs
using a separable decomposition and keep only a few low-order approximation terms, each consist-
ing of a purely view-dependent and a purely light-dependent component. In the precomputation
step, for every vertex we sample its visibility and compute a direct illumination transport vector
corresponding to each BRDF term. We use modern graphics hardware to accelerate this step,
and further compress the data using a non-linear wavelet approximation. The direct illumination
pass is followed by one or more interre
ection passes, each of which gathers compressed transport
vectors from the previous pass to produce global illumination transport vectors. To render at run
time, we dynamically sample the lighting to produce a light vector, also represented in a wavelet
basis. We compute the inner product of the light vector with the precomputed transport vectors,
and the results are further combined with the BRDF view-dependent components to produce
vertex colors. We describe acceleration of the rendering algorithm using programmable graphics
hardware, and discuss the limitations and tradeo s imposed by the hardware.