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R. Habel, B. Mustata, M. Wimmer:
"Efficient Spherical Harmonics Lighting with the Preetham Skylight Model";
Talk: Eurographics, Kreta, Griechenland; 2008-04-14 - 2008-04-18.

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.

Project Head Michael Wimmer:
Realistische Echtzeitbeleuchtungssimulation von Bäumen