Eric Johnsson wrote:
> 
> Hi.
> 
> I have seen some very nice pictures in p.b.i. showing outdoor scenes, that
> uses radiosity to simulate the light from the sun/sky.
> 
> I have not so much experience with radiosity, and would apprechiate if
> someone could give me some hints on how to simlate an outdoor scene using
> the radiosity functions in MegaPOV.

Ordinary default radiosity should suffice for most scenes; if it's
having TOO much of an effect, try cutting the brightness a little, as needed.

Mind you, this represents skylight. I've never heard of anyone using
radiosity to simulate direct sunlight, and you're probably better off
using a light_source of some kind for that.

> What is the main differences between a cloudless sky compared with a sky
> with a lot of clouds (e.g. cumulus), or an overcast sky...?

Assuming you've seen what those look like in real life, a little thought
should make the answer obvious.

I'll note one thing: if you're trying to simulate an overcast sky, you
would do well to do something to artificially brighten your scene a
little unless you intend for your image to be viewed on a black
background in a dark room. In real life, the eye adjusts to the dim
lighting of an overcast sky making everything seem to be acceptably
bright, but when a "realistic" overcast sky scene is viewed in tandem
with ordinary room illumination, the eye adjusts to the room lighting,
causing the image to seem to fade to darkness by comparison.

> Concerning the "diffuse light" from the sky, is this light in a shade of
> blue since the sky is blue?

If you're not sure about this, you need to get out more. Someone left a
big ol' reference sky lying out there for you to use.

> Is it possible to calculate the "color" of the
> sun at different times (i.e. sunset/mid-day/dawn)...?

I suppose, yeah.. but you could probably guess and get something reasonable.

-Xplo

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