Efficient Spherical Harmonics Lighting with the Preetham Skylight Model

Ralf Habel, Bogdan Mustata, Michael Wimmer
Efficient Spherical Harmonics Lighting with the Preetham Skylight Model
In Eurographics 2008 - Short Papers, pages 119-122. April 2008.
[ Preprint]
Content:

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Abstract

We present a fast and compact representation of a skylight model for spherical harmonics lighting, especially for outdoor scenes. This representation allows dynamically changing the sun position and weather conditions on a per frame basis. We chose the most used model in real-time graphics, the Preetham skylight model, because it can deliver both realistic colors and dynamic range and its extension into spherical harmonics can be used to realistically light a scene. We separate the parameters of the Preetham skylight models' spherical harmonics extension and perform a polynomial two-dimensional non-linear least squares fit for the principal parameters to achieve both negligible memory and computation costs. Additionally, we execute a domain specific Gibbs phenomena suppression to remove ringing artifacts.

Additional Files and Images

Additional files:
Movie Movie: Sky-SH
Preprint Preprint: Efficient Spherical Harmonics Lighting with the Preetham Skylight Model
More files:
C-Implementation with preetham coefficients
C-Implementation with preetham coefficients




BibTeX

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@inproceedings{Habel_08_SSH,
  title =      "Efficient Spherical Harmonics Lighting with the Preetham
               Skylight Model",
  author =     "Ralf Habel and Bogdan Mustata and Michael Wimmer",
  year =       "2008",
  abstract =   "We present a fast and compact representation of a skylight
               model for spherical harmonics lighting, especially for
               outdoor scenes. This representation allows dynamically
               changing the sun position and weather conditions on a per
               frame basis. We chose the most used model in real-time
               graphics, the Preetham skylight model, because it can
               deliver both realistic colors and dynamic range and its
               extension into spherical harmonics can be used to
               realistically light a scene. We separate the parameters of
               the Preetham skylight models' spherical harmonics extension
               and perform a polynomial two-dimensional non-linear least
               squares fit for the principal parameters to achieve both
               negligible memory and computation costs. Additionally, we
               execute a domain specific Gibbs phenomena suppression to
               remove ringing artifacts.",
  pages =      "119--122",
  month =      apr,
  booktitle =  "Eurographics 2008 - Short Papers",
  editor =     "Katerina Mania and Erik Reinhard",
  issn =       "1017-4656",
  publisher =  "Eurographics Association",
  location =   "Crete, Greece",
  keywords =   "Natural Phenomena, Spherical Harmonics, Skylight",
  URL =        "http://www.cg.tuwien.ac.at/research/publications/2008/Habel_08_SSH/",
}