"Trevor G Quayle" <Tin### [at] hotmailcom> wrote:
>
> There are still some black dots.  This is a result of the
> reflection/refraction of the material.  A lot of it is actually reflection of
> the background which is black by default (try putting background{rgb 1} in to
> see the difference.  Some of this will get minimized with AA, but it can never
> disappear completely.

Yes, with high reflectance/transparency and high IOR for an object, the
surroundings of the scene can have a major (and sometimes misleading) effect on
the look of it.

Hi, Mike--

Concerning adc_bailout: Setting it to zero disables it, and the total rays shot
are completely dependent on the max_trace_level setting. Since your object has
a min,max reflection of 0,1 (the 1 being important here), and since your
object's texture has filtration of 1 (again, the max), POV-Ray will probably
continue shooting rays practically *forever* if you set max_trace_level to 255.
Have you taken a look at messages when running your scene with max_trace_level
at 20?  I imagine it maxes out--so there would still probably be black spots.
(Even THAT is a long render, as I discovered!) I generally avoid using max
reflection and max transparency in the same object--in some instances, it can
cause the render to slow almost to a stop, depending on max_trace_level. I've
even had the program crash on me.

I see that you're using conserve_energy with your variable reflection, which
*should* take care of some of these problems; but I don't know enough about
that feature to say yes or no.

Setting adc_bailout to some relatively high, crude value--like .1--will not
usually create dark spots.  Instead, it just makes the object look 'bland' and
darker overall. Not something you'd want to do, of course. :-)

You might also want to take a look at 3.3.3.7 in the documentation. It says,
"...a perfect mirror or perfectly clear surface will not be optimizable by
ADC." That may have some relevance to your scene.

Ken W.

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