A Meshless Hierarchical
Representation for Light Transport
Jaakko Lehtinen,
Matthias Zwicker,
Emmanuel Turquin,
Janne Kontkanen,
Frédo Durand,
François Sillion,
Timo Aila
ACM Transactions in Graphics 27(3) (Proc. SIGGRAPH 2008).
Abstract
We introduce a meshless hierarchical representation for solving
light transport problems. Precomputed radiance transfer (PRT) and
finite elements require a discrete representation of illumination over
the scene. Non-hierarchical approaches such as per-vertex values
are simple to implement, but lead to long precomputation. Hierarchical
bases like wavelets lead to dramatic acceleration, but in
their basic form they work well only on flat or smooth surfaces. We
introduce a hierarchical function basis induced by scattered data
approximation. It is decoupled from the geometric representation,
allowing the hierarchical representation of illumination on complex
objects. We present simple data structures and algorithms for constructing
and evaluating the basis functions. Due to its hierarchical
nature, our representation adapts to the complexity of the illumination,
and can be queried at different scales. We demonstrate the
power of the new basis in a novel precomputed direct-to-indirect
light transport algorithm that greatly increases the complexity of
scenes that can be handled by PRT approaches.
Acknowledgments
The authors thank Michael Doggett, Michael Garland, Nicolas
Holzschuch, Tomas Akenine-Möller, Andy Nealen, Sylvain Paris,
Jussi Räsänen, and Lauri Savioja for feedback; Stephen Duck for
the Great Hall scene; DreamWorks Animation for the Jade Palace
model; Eric Tabellion and Andrew Pearce for help with the Jade
Palace model; the Stanford Computer Graphics Laboratory for the
David model; Marko Dabrovic (www.rna.hr) for the Sponza Atrium
model. This research was supported by the National Technology
Agency of Finland, Anima Vitae, AMD Research Finland,
NVIDIA Helsinki, Remedy Entertainment, the Academy of Finland
(Grant 108 222), the INRIA Associate Research Team ARTIS/
MIT, and NSF CAREER 044756. Jaakko Lehtinen acknowledges
an NVIDIA Fellowship. Frédo Durand acknowledges a Microsoft
Research New Faculty Fellowship and a Sloan Fellowship.
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More Applications
The basis can be applied in a wide variety of situations. For two further examples,
you can also take a look at an earlier version
of this work.
Jaakko Lehtinen, Oct 4 2008
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