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9.11. Precomputed Radiance Transfer 437
nation of a set of images into a texture consisting of polynomial coefficients
that capture bumpiness, self-shadowing, and interreflection effects. Most
kinds of view-independent effects can be modeled, as long as they are local
(not affected by the large-scale curvature or shape of the surface). The
light directions are parameterized in the tangent space of the surface, so
these textures can be mapped onto arbitrary objects and tiled. Wong et
al. [1368] present a similar technique that uses radial basis functions, rather
than polynomials.
The SIGGRAPH 2005 course [635] on precomputed radiance transfer
provides a good overview of research in the area. Lehtinen [755, 756] gives
a mathematical framework that can be used to analyze the differences
between the various algorithms, and to develop new ones.
Further Reading and Resources
Hasenfratz et al. [508] provide an excellent overview of shadow algorithms
developed up through 2003. Diefenbach’s thesis [252] discusses and con-
trasts reflection, refraction, and shadow volume techniques in depth, as
well as transparency, light volume filtering, and other techniques. Despite
its age, it provides interesting food for thought. Mittring’s article on de-
veloping graphics algorithms for the game Crysis [887] is a fascinating case
study. It discusses implementation of a number of global phenomena and
many other graphical elements.
A valuable reference for information on BRDFs, global illumination
methods, color space conversions, and much else is Dutr´e’s free online
Global Illumination Compendium [287]. Pharr and Humphrey’s book Phys-
ically Based Rendering [1010] is an excellent guide to non-interactive global
illumination algorithms. What is particularly valuable about their work is
that they describe in depth what they found works. Glassner’s Principles
of Digital Image Synthesis [408, 409] discusses the physical aspects of the
interaction of light and matter. Advanced Global Illumination by Dutr´e
et al. [288] provides a foundation in radiometry and on (primarily offline)
methods of solving Kajiya’s rendering equation.
Implementing radiosity algorithms is not for the faint of heart. A good
practical introduction is Ashdown’s book [40], sadly now out of print. Suf-
fern’s book [1228] is an excellent detailed guide for building a basic ray
tracer. Shirley and Morley’s book on ray tracing [1171] has less coverage of
the basics, and more about advanced algorithms. The ray tracing book by
Glassner et al. [404], though old, provides some useful material. The on-
line publication The Ray Tracing News [479] presents articles and describes
resources related to the topic.
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