Kari Kivisalo wrote:
> 
> I would like to do some radiosity testing with outdoors scenes and
> for this I need to know how much energy comes just from the sun
> to the surface and how much from the rest of the sky. All I need is
> the ratio maybe for a clear sky and 50% cloudy.

That depends on how high in the sky the sun is.  At sunrise or sunset,
the sun is scattered through a maximum thickness of atmosphere, and half
of the lit sky is blocked.  At local noon, the sun is brightest, but a
larger proportion of the sky is scattering light as well.  Also,
remember that the sky is typically brighter closer to the sun, even at
noon.  It's not realistic for the sky to have uniform brightness unless
it's either uniformally dark or overcast.

Sorry if this makes life more complicated without answering your
question.

-Mark Gordon

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