illumination

Hello grassusers,
I'm using the Spearfish database to try out some wildland fire risk mapping
methods. For one of them I need to know the insolation. Does any one know a
method to generate a illumination map using a given solar elevation angle ?
Thanks a lot, Moniek Vesseur.
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Name: Eric den Breejen x Internet: breejen@cemef.cma.fr
Mail: Ecole des Mines de Paris x Address : Ecole des Mines de Paris
       Cemef/IAM x
       BP 207 x
       06904 Sophia Antipolis cedex x
       France x
Phone: ++33-93.95.74.86 x Fax : ++33-93.65.43.04
                                     x
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