POV-Ray : Newsgroups : povray.general : weird effect or normal : Re: weird effect or normal Server Time
14 Apr 2024 13:48:17 EDT (-0400)
  Re: weird effect or normal  
From: Ilya Razmanov
Date: 17 Mar 2024 01:42:00
Message: <65f682a8@news.povray.org>
On 16.03.2024 19:06, David Kraics wrote:

> I don't know what that does or is. Honestly, even after 30 or so years of using
> this program, I only know how to use some of its features.

As it was explained already, it controls the number of light/surface 
interactions for a ray. Most of my scene files, especially 
auto-generated, start with:

   max_trace_level 3
   adc_bailout 0.01
   assumed_gamma 1.0

because objects are opaque and rather "plastic" and not expected to 
produce complex reflections and stuff, so even default max_trace_level 5 
is excessive and only makes rendering slower, I can improve rendering 
speed without quality problems by reducing max_trace_level from 5 to 3.

However, when you start using glasses, things become more complex 
because glass have not only outer surface, but inner surface. It have 
not only front, but back as well. So, if you have several glass objects 
layered or nested, surfaces multiply <s>and only one man can stop 
them</s>. The first symptom of too small max_trace_level is part of the 
scene turning black.

My morning doses of phosphodiesterase inhibitor and N-cholinomimetics 
are not completely uptaken yet, so I refuse to *think* about your scene, 
and just suggest to edit scene header to something like

   max_trace_level 30
   // plus something else you may have here already

and see if something (beside rendering time) change. If it does, than 
trace level is the source of the problem, and you may start counting 
surfaces to define minimal sufficient value.

Ilyich the Toad

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