Am 3/21/2018 um 0:00 schrieb Kenneth:
> I do see the reason for rad brightness 1.0 now; but it's the turning down of the
> sky brightness that puzzles me.
> 
> Still assuming a low-dynamic-range setup, not HDR: If I use a sky photo of
> clouds that looks nice-- set to emission 1.0, and which might actually appear in
> the rendered scene-- turning down its brightness (i.e., emission value) will
> cause it to have a 'dull' visual look in the render (what was once full white
> now being a somewhat darker gray, for instance.) While that may indeed 'balance'
> the radiosity lighting as far as color-clipping of object surfaces goes, the
> visual appearance of the 'sky' itself is now dull. (That was my reasoning for
> making two identical photo-mapped sky spheres-- where the *visible* sky is still
> at emission 1.0)
> 

Besides of what others have said I'd like to add that it is a common 
mistake to define the diffuse reflectance way too strong. E.g. a *white* 
piece of paper is something like rgb <0.5, 0.48, 0.42> with diffuse 0.6 
and as it happens I just measured (for some project of mine) some white 
silk and its diffuse reflectance is rgb <0.42, 0.40, 0.38>.
On the other hand light sources are not limited to rgb <1,1,1> and 
especially the value for sunlight should be much higher. This gives you 
(with proper radiosity use i.e. brightness = 1) easily a nice and 
realistic lighting with good contrast and - most important when you aim 
for realism - without any tweaking.

-Ive

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