Alain <kua### [at] videotronca> wrote:
>
> Don't forget that using diffuse 1 is NOT realistic. A very bright
> surface may have a diffuse as high as 0.95 or even 0.98, never 1.
>
> Using diffuse 1 is a very good way to get washed out colours.
>

and Ive wrote...
> ...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

Yes, I'm now understanding that concept as well, far better than I used to.

My prior assumption about a typical low-dynamic-range scene-- of almost always
using diffuse 1.0 for an object's surface-- was based on several factors
(assuming that both ambient and emission are at 0.0 for argument's sake, and NO
radiosity):  With a light_source set to rgb 1.0, and an object's color of
<.3,.5,.7> --with no additional phong or specular to complicate things-- my
understanding was that the very *brightest* color of the object's surface would
never exceed <.3,.5,.7> (but could  go below that, naturally.) That may still be
the case with a purely white light_source-- but the addition of anything else
(radiosity, colored light etc) naturally complicates things, so that
*something* in the scene needs to be tweaked (in brightness or whatever) to keep
any parts of the render from 'clipping' in brightness-- past the 1.0 maximum
pixel level for a LDR render, as Clipka mentioned.

From all that's been said so far, it appears that this tweaking needs to be done
*by eye*, to try and make sure that any clipping is kept to a minimum. Perhaps
the 'by eye' method is just a given-- and it's certainly what I had to do in
v3.6.x days (though with limited success.) *Which* parts to tweak can be ...
complicated, though. Even with POV-ray's up-to-date changes re: radiosity,
assumed_gamma etc, a successful/realistic render nevertheless appears to require
a *by eye* approach.

I don't have any complaints about that need; and I'm certainly open to being
corrected if I'm wrong ;-)

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