POV-Ray : Newsgroups : povray.beta-test : weird white stain with beta povray v3.8.0 (not with povray v3.7.0) Server Time
27 Sep 2022 20:40:53 EDT (-0400)
  weird white stain with beta povray v3.8.0 (not with povray v3.7.0) (Message 21 to 23 of 23)  
<<< Previous 10 Messages Goto Initial 10 Messages
From: Kenneth
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 23 Jan 2022 12:45:00
Message: <web.61ed93d0c82cc78e4cef624e6e066e29@news.povray.org>
Alain Martel <kua### [at] videotronca> wrote:

> > // the large sky-sphere
> > sphere{0, 1
> > pigment{rgb .1}
> >      finish{ambient 0 diffuse 0 emission 1}
> >      scale 8000 // change to 50
> >     // hollow on // does not seem to be necessary-- the media objects and
> >                  // rad patches show up anyway
> >      no_image
> > }
>
> Have you tried to replace that large sphere with a sky_sphere ? Or even
> a simple background statement if the pigment is solid ?
> Some options :
>
> background{ rgb 0.1 }
>
> sky_sphere{
>  pigment{ rgb 0.1 }
>    }
>

Good suggestions. I tried both of those as a substitute for the large sphere--
and now there are NO bright rad-patch artifacts, in either case! So that sphere
(and its scale) seems to be causing a real/mysterious problem.

I tried one more simple test of that sphere: *creating* it with a radius of 8000
vs. *scaling* it to be so. But that didn't solve the problem.

Thanks Alain; this result *might* indicate a bug, regarding use of such an
actual sphere along with radiosity's 'media ON' switch.


Post a reply to this message

From: Kenneth
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 24 Jan 2022 03:10:00
Message: <web.61ee5de4c82cc78e4cef624e6e066e29@news.povray.org>
> Alain Martel <kua### [at] videotronca> wrote:
> >
> > Have you tried to replace that large sphere with a sky_sphere ? Or even
> > a simple background statement if the pigment is solid ?
>
> Good suggestions. I tried both of those as a substitute for the large sphere--
> and now there are NO bright rad-patch artifacts, in either case!

Well, I spoke too soon. The reason I didn't see any patches-- or any rad/media
interaction at all-- was because my sky_sphere color and emission color were
just too dim to produce them. In my most recent test code posted earlier, use
the sky_sphere at rgb 0.1, and try emission 1*<0.1,1.0,0.1> to see the media
cylinders, then emission 250*<0.1,1.0,0.1> to see the bright patches again.

So that media object being half-embedded seems to be the real problem... along
with rad's 'media ON' switch.

But I find it strange that the sky_sphere produces its own particular radiosity
brightness, versus the enclosing-sphere object imparting its *variable* rad
brightness depending on its size.

A mystery for now.


Post a reply to this message

From: Alain Martel
Subject: Re: weird white stain with beta povray v3.8.0 (not with povray v3.7.0)
Date: 24 Jan 2022 08:01:33
Message: <61eea32d$1@news.povray.org>
Le 2022-01-24 à 03:05, Kenneth a écrit :
>> Alain Martel <kua### [at] videotronca> wrote:
>>>
>>> Have you tried to replace that large sphere with a sky_sphere ? Or even
>>> a simple background statement if the pigment is solid ?
>>
>> Good suggestions. I tried both of those as a substitute for the large sphere--
>> and now there are NO bright rad-patch artifacts, in either case!
> 
> Well, I spoke too soon. The reason I didn't see any patches-- or any rad/media
> interaction at all-- was because my sky_sphere color and emission color were
> just too dim to produce them. In my most recent test code posted earlier, use
> the sky_sphere at rgb 0.1, and try emission 1*<0.1,1.0,0.1> to see the media
> cylinders, then emission 250*<0.1,1.0,0.1> to see the bright patches again.
> 
> So that media object being half-embedded seems to be the real problem... along
> with rad's 'media ON' switch.
> 
> But I find it strange that the sky_sphere produces its own particular radiosity
> brightness, versus the enclosing-sphere object imparting its *variable* rad
> brightness depending on its size.
> 
> A mystery for now.
> 
> 
> 
> 

New suggestion :
Scale your media container by <0.5, 1, 1> and move them up so that it is 
entirely above the surface. Even leave a tiny gap between it and the 
surface.


Post a reply to this message

<<< Previous 10 Messages Goto Initial 10 Messages

Copyright 2003-2021 Persistence of Vision Raytracer Pty. Ltd.