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Schlagwörter:
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Zusammenfassung:
Precomputed Radiance Transfer allows interactive rendering of objects
illuminated by low-frequency environment maps, including self-shadowing and
interreflections. The expensive integration of incident lighting is partially
precomputed and stored as matrices.
Incorporating anisotropic, glossy BRDFs into precomputed radiance
transfer has been previously shown to be possible, but none of the
previous methods offer real-time performance. We propose a new
method, \textit{matrix radiance transfer}, which significantly
speeds up exit radiance computation and allows anisotropic BRDFs.
We generalize the previous radiance transfer methods to work with a
matrix representation of the BRDF and optimize exit radiance
computation by expressing the exit radiance in a new, directionally
locally supported basis set instead of the spherical harmonics. To
determine exit radiance, our method performs four dot products per
vertex in contrast to previous methods, where a full matrix-vector
multiply is required. Image quality can be controlled by adapting
the number of basis functions. We compress our radiance transfer
matrices through principal component analysis (PCA). We show that it
is possible to render directly from the PCA representation, which
also enables the user to trade interactively between quality and
speed.
