"Kenneth" <kdw### [at] earthlinknet> wrote:
> "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.

Thanks for all the info.  I have trouble looking at the messages on the
statistics screen because I am running megapov on a mac and it does not seem to
give all the same information.  Setting the filter variable to 0.8 seems to have
made things speed up a bit.  Still I only get significant results if I turn
adc_bailout off and pump up the max_trace_level.  My goal for all this was to
create a very scientifically accurate scene (hence the conserve energy and
fresnel on).  I did see the thing you were talking about, with the perfect
mirrors and adc_bailout, 2.3.3.7 actually, and it might explain things.

Oh, I had a post in the new user section where it started off as how to make the
egg crate pattern and it has evolved, so I reposted it. Sorry for the chaos this
might have caused.

-Mike

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