POV-Ray : Newsgroups : povray.general : Very thin material - how to avoid color changes? Server Time
3 Dec 2024 21:26:50 EST (-0500)
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From: spigor
Subject: Re: Very thin material - how to avoid color changes?
Date: 1 Nov 2024 07:40:00
Message: <web.6724bd53bc0de7d951a0d5861a8e06@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:

>
> > I also use:
> > global_settings{
> >      assumed_gamma 1
> >      radiosity{
> >          pretrace_start 1
> >          pretrace_end 1
> >          count 400
> >          recursion_limit 1
> >          nearest_count 1
> >          error_bound 0.05
> >      }
> > }
>
> That radiosity block make me twitch.
> pretrace_start and pretrace_end 1 are only to be used for the last pass
> of multipass rendering when all of the radiosity data have been saved
> from a previous pass.
> Even the default of 0.08 and 0.01 are to large. Using pretrace_end
> 0.0025 or less tend to give better result, and is often faster overall
> as more, and better, data are collected during pretrace.
>
> count is OK. Using the two value version will often improve the quality
> at nearly zero cost.
> count 400, 1111
>
> error_bound is acceptable for a scene using only radiosity illumination.
> If you use conventional light, then the default of 0.5 is sufficient.
>
> nearest_count 1 will often cause artifacts. Better to use the adaptive
> version : nearest_count 20, 3
>
>
> You should NOT use diffuse 1. It can cause some nasty side effect.
> Better keep the default value.
> So, change that #default to just :
> #default{finish{ambient 0}}
>
> And use emission 1 in the finish block to create some light emitting object.

Thanks! I found this comment to be very helpful!


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From: spigor
Subject: Re: Very thin material - how to avoid color changes?
Date: 2 Nov 2024 06:45:00
Message: <web.672600b0bc0de7d951a0d5861a8e06@news.povray.org>
"spigor" <nomail@nomail> wrote:

> Thanks! I found this comment to be very helpful!

Also, I'm sorry for my ignorance on these parameters. I'm an occasional user of
this superb software. I did my last project around 2006
(https://paulstgeorge.com/travelling-curves/), before that probably in the 90s.
It's a unique experience each time and I always learn something new, but it's
possible to get magnificent and fully controlled results faster than in CAD.
Thank you for everything and all the best!


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From: jr
Subject: Re: Very thin material - how to avoid color changes?
Date: 2 Nov 2024 12:15:00
Message: <web.67264f59bc0de7dbdf7d1766cde94f1@news.povray.org>
hi,

"spigor" <nomail@nomail> wrote:
> Also, I'm sorry for my ignorance on these parameters. I'm an occasional user of
> this superb software. I did my last project around 2006
> (https://paulstgeorge.com/travelling-curves/), before that probably in the 90s.

only had time for a very cursory look, alas, but will re-visit.  ('carpet
castle' appealed :-))

hope you'll find plenty "excuses" to continue using POV-Ray in future projects.
cheers.


regards, jr.


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