On 2016-11-02 08:22 PM (-4), omniverse wrote:
 > I'm going to take the initiative to move this into a separate message 
thread due
 > to Clipka asking not to reply to posts in the "survey" thread.

Thanks for that.  As such, this reply is to Warp, not to you.

> Warp <war### [at] tagpovrayorg> wrote:
>> I would like to know your opinion on these as well:
>>
>> 1) Which one of these images do you think looks more realistic?
>>
>> http://koti.kapsi.fi/warp/media/pov37_test1.png
>> http://koti.kapsi.fi/warp/media/pov37_test2.png

I cannot say, as that would depend on the environmental lighting 
conditions and material properties.

>> 2) Currently, when using assumed_gamma 1 in povray 3.7 mode, default
>> color values in things like the ambient finish do not get adjusted in
>> terms of srgb, but remain in their rgb values (for example, the default
>> ambient finish is "rgb 0.1"), which means that a change in assumed_gamma
>> will affect their brightness.
>>
>> The second image above was rendered by explicitly specifying the default
>> ambient finish (using the #default directive in the scene file) using
>> "srgb". Without this explicit setting, ie. using the default value, the
>> image looks like this:
>>
>> http://koti.kapsi.fi/warp/media/pov37_test4.png
>>
>> (It's essentially impossible to get any shades are darker than that due to
>> the default ambient finish.)
>>
>> So my question is: Should POV-Ray define default colors (eg. in the ambient
>> finish, and anywhere else where there are default colors) in terms of srgb
>> (which would result in the second image by default, without having to
>> explicitly set those defaults), or is the current functionality ok (which
>> by default results in the third image).

As far as I'm concerned, the default ambient is just a place holder. 
That said, on those occasions when I forgo radiosity, my ambient value 
is usually greater than rgb 0.1, even though I use assumed_gamma 1.  The 
scenes in which I use less than rgb 0.1 all have a very dark 
environment.  This is to say that rgb 0.1 is a perfectly fine default, 
and I would certainly not lower it.

(I never use srgb in ambient statements because it is physically 
meaningless to me--akin to why I do not use assumed_gamma 2.2.  When I 
need a darker ambient, I just use a smaller rgb value.  N.B. srgb in a 
pigment color is a completely different matter.)

The problem with pov37_test4.png, as I see it, is not that the ambient 
is too high, but that there is no ambient occlusion--the feature that, 
to me, most makes radiosity scenes so much more convincing than 
non-radiosity scenes.  One way to simulate ambient occlusion would be to 
use fill lights, and of course, in that case, lowering the ambient would 
be appropriate.

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