clipka <ano### [at] anonymousorg> wrote:
>
> Actually, the safest bet is: Don't set radiosity brightness to
> /anything/ other than 1.0 in the first place! It wrecks realism anyway.
>
> (A reasonable case can be made for brightness values slightly _above_
> 1.0, when recursion_limit is set particularly low (2 or even 1), to
> compensate for the fact that this reduces the overall brightness of the
> scene a bit. But brightness values below 1.0 are of the devil. Don't go
> near them.)

Thinking about this further: I assume you mean, when using a HDR light probe for
the sky and no other lights in the scene? A brightness value of 1.0 would make
sense.

Whereas, when using a typical LDR sky photo, and a (single) light in the scene
for the 'Sun', a rad brightness value of 1.0 could be too bright, for various
reasons.

Given that the objects in the scene have  finish {diffuse 1.0 emission 0} --
with ambient turned off automatically-- and a light_source of rgb 1 (or more
likely less than that), it would *seem* natural to turn down rad's brightness
below 1.0. So that any object surfaces never exceed a surface brightness of 1.0
max; otherwise, there's a danger of washing out the object colors. It would all
depend on how bright the single light_source is: if it's set to rgb 0.6, then
rad brightness should not exceed 0.4, according to my theory.

Of course, this all depends on light_source/surface brightness and rad
brightness being simply additive (i.e., the combination can go beyond 1.0.)
That's what I've always assumed, anyway.

However, I do see a major problem with my argument: The parts of the scene in
*shadow* are only receiving the rad lighting-- and such shadow illumination
would *vary* depending on my light_source brightness. Not very logical, I admit.
(Or more specifically, not 'realistic.')  So I guess such a lighting scenario
is, by default, not 'realistic'  at all, but just an attempt to make the scene
'pleasing to the eye.'  I.e., balancing 'Sunlight' brightness against shadow
brightness, just to prevent any colors from being washed out.

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