=?ISO-8859-1?Q?J=F6rg_=27Yadgar=27_Bleimann?= <yaz### [at] gmxde> wrote:
> High!
>
> For an flyby sequence over my - still very crude - Afghan landscape I
> added a sky with cheap bozo clouds on a hollow sphere 6000 metres above
> ground... and when I started rendering the animation, I noticed that a
> part of the clouds, which should, even when seen from the unlit side, be
> light grey, is rendered almost black!
>
> As this blackness doesn't show up when leaving out the terrain, I
> concluded that this is caused by radiosity, which darkens the clouds
> from  the shadowed terrain below them (the darker mountains on the right
> half the horizon in the first image).
>
> So, I would like to know if there is a method to exclude an object from
> being affected by radiosity...
>
> See you in Khyberspace!
>
> Yadgar
>
> Now playing: Feuerland (Michael Rother)

I don't know if you can exclude an object from exhibiting radiosity, but I'm
guessing that your sky sphere is brightly coloured in both the top part
(northern hemisphere) & the bottom part (southern hemisphere).  In which
case, when you remove the ground, the bottom of your clouds are being lit
from below by the bottom part.  When you put the ground in, you are
blocking the (unnatural) light from the sky below, leaving the clouds as
dark as they should be.

If you *want* the clouds to be lit from below, you could try using a
shadowless light_source some way below the ground, maybe putting it in a
light group with only the cloud sphere to prevent any other objects from
being underlit.

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