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Fast Global Illumination on Dynamic Height Fields
Author(s) -
Nowrouzezahrai Derek,
Snyder John
Publication year - 2009
Publication title -
computer graphics forum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.578
H-Index - 120
eISSN - 1467-8659
pISSN - 0167-7055
DOI - 10.1111/j.1467-8659.2009.01490.x
Subject(s) - radiance , precomputation , global illumination , rendering (computer graphics) , computer science , visibility , ray tracing (physics) , pyramid (geometry) , computer vision , mathematics , optics , algorithm , geometry , physics , computation
Abstract We present a real‐time method for rendering global illumination effects from large area and environmental lights on dynamic height fields. In contrast to previous work, our method handles inter‐reflections (indirect lighting) and non‐diffuse surfaces. To reduce sampling, we construct one multi‐resolution pyramid for height variation to compute direct shadows, and another pyramid for each indirect bounce of incident radiance to compute inter‐reflections. The basic principle is to sample the points blocking direct light, or shedding indirect light, from coarser levels of the pyramid the farther away they are from a given receiver point. We unify the representation of visibility and indirect radiance at discrete azimuthal directions (i.e., as a function of a single elevation angle) using the concept of a “casting set” of visible points along this direction whose contributions are collected in the basis of normalized Legendre polynomials. This analytic representation is compact, requires no precomputation, and allows efficient integration to produce the spherical visibility and indirect radiance signals. Sub‐sampling visibility and indirect radiance, while shading with full‐resolution surface normals, further increases performance without introducing noticeable artifacts. Our method renders 512×512 height fields (> 500K triangles) at 36Hz.