So I'd expect in a scene with no lights and no ambient values I'd get a pure
black render, but I can see my objects.  What am I missing?  The scene is
just a blue sphere and nothing else.

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> So I'd expect in a scene with no lights and no ambient values I'd get a
pure
> black render, but I can see my objects.  What am I missing?  The scene is
> just a blue sphere and nothing else.

Have you set "ambient_light" in global_settings to 0? And did you set the
ambient in the finish of the objects to 0? If both are the case, then you
should get a pure black image, unless you're using some emitting media.
Otherwise, the ambient-term will take care that an object is never 100%
black (unless the texture is black itself).

You might want to look up "ambient" and "ambient_light" in the docs.

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

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news:web.425b82292c3b529f51a594900@news.povray.org...
> So I'd expect in a scene with no lights and no ambient values I'd get a
pure
> black render, but I can see my objects.  What am I missing?  The scene is
> just a blue sphere and nothing else.
>
If not precised, default ambient value is 0.1
If you want to modify that, write
#default {
  texture { finish{ambient 0} }
}
at the begining of your file
(it can be even compulsory if you use radiosity because ambient>0 emits
light in this case)

Marc

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Tim Nikias <JUSTTHELOWERCASE:timISNOTnikias(at)gmx.netWARE> wrote:
> Have you set "ambient_light" in global_settings to 0? And did you set the
> ambient in the finish of the objects to 0?

  If ambient_light in global_settings is 0 then the ambient of objects
do not matter.

> If both are the case, then you
> should get a pure black image, unless you're using some emitting media.

  sky_sphere is not affected by amient_light (and probably other more
unusual features such as rainbow).

-- 
#macro N(D)#if(D>99)cylinder{M()#local D=div(D,104);M().5,2pigment{rgb M()}}
N(D)#end#end#macro M()<mod(D,13)-6mod(div(D,13)8)-3,10>#end blob{
N(11117333955)N(4254934330)N(3900569407)N(7382340)N(3358)N(970)}//  - Warp -

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> > Have you set "ambient_light" in global_settings to 0? And did you set
the
> > ambient in the finish of the objects to 0?
>
>   If ambient_light in global_settings is 0 then the ambient of objects
> do not matter.

Hm, you're correct, and I actually do know that. My line of thought was:
"These two are responsible, do one or the other." Maybe I should have
phrased it differently. Then again, in povray.newusers I try never to give
the answer right away, but give a very obvious hint where to look. :-)

>   sky_sphere is not affected by ambient_light (and probably other more
> unusual features such as rainbow).

I think fog would be in the same category of "ambient doesn't matter here",
and might even influence the image in the way Mienai is referring to, but
that's just a wild guess.

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

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