Effiicent Wavelet Rotation for Environment Map Rendering

Real-time shading with environment maps requires the ability to rotate the global lighting to each surface point's
local coordinate frame. Although extensive previous work has studied rotation of functions represented by spherical
harmonics, little work has investigated efficient rotation of wavelets. Wavelets are superior at approximating
high frequency signals such as detailed high dynamic range lighting and very shiny BRDFs, but present difficulties for interactive rendering due to the lack of an analytic solution for rotation. In this paper we present
an efficient computational solution for wavelet rotation using precomputed matrices. Each matrix represents the
linear transformation of source wavelet bases defined in the global coordinate frame to target wavelet bases defined in sampled local frames. Since wavelets have compact support, these matrices are very sparse, enabling
efficient storage and fast computation at run-time. In this paper, we focus on the application of our technique to
interactive environment map rendering. We show that using these matrices allows us to evaluate the integral of
dynamic lighting with dynamic BRDFs at interactive rates, incorporating efficient non-linear approximation of
both illumination and reflection. Our technique improves on previous work by eliminating the need for prefiltering
environment maps, and is thus significantly faster for accurate rendering of dynamic environment lighting with
high frequency reflection effects.
Categories and Subject Descriptors (according to ACM CCS): I.3.7 [Computer Graphics]: Three-Dimensional
Graphics and Realism;

Rui Wang (University of Virginia)
David Luebke (University of Virginia)
Greg Humphreys (University of Virginia)
Publication Date: 
Thursday, June 1, 2006
Research Area: 
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