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29 Jul 2024 18:16:29 EDT (-0400)
  Question about radiosity (Message 1 to 4 of 4)  
From: MichaelJF
Subject: Question about radiosity
Date: 20 Nov 2013 15:50:01
Message: <web.528d1fed6bc85a0ba8a8fb540@news.povray.org>
Hi all,

radiosity is still a thing I have not really investigated so far, so I rely on
the settings in rad_def.inc very often. So this one is done with OutdoorLQ,
media and normals turned on. I started the scene with Robert's Catenoid image
from the minimalism round of the irtc. He was so kind to share his code back
then, and I really thank him for this. In the end only his area light remained
within my scene (dimmed a little bit). The wall is an isosurface, the snail a
mixture of a blob and a mesh (taken from my first TC-RTC entry) and the lantern
completely done with CSG and one of the first models I created using POV. The
candle light is an emissive media (a little bit to bright here IMO). The surface
of the glass parts of the lantern has a designed structure as you can see and
(at the flat parts) bumpy normals. Can this explain the distant green spots at
the wall? I'm not sure that I have a failure with the radiosity settings.
Unfortunatelly this "simple" scene renders a while (In fact 2 days and some 30
minutes).

And to notice: The original lantern was a very cheap one. Nice to the eye in a
way, but there were holes between it's parts I modelled too by intention.

BTW: My wife has taken it as a photography of her little garden lantern, so it
seems, I did not all wrong;-)

Best regards,
Michael


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From: MichaelJF
Subject: Re: Question about radiosity
Date: 20 Nov 2013 16:00:00
Message: <web.528d2221f97fc515a8a8fb540@news.povray.org>
Seems the image was lost with my first posting.


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From: clipka
Subject: Re: Question about radiosity
Date: 20 Nov 2013 16:41:11
Message: <528d2c77$1@news.povray.org>
Am 20.11.2013 21:57, schrieb MichaelJF:
> Seems the image was lost with my first posting.

The artifacts don't look like typical radiosity artifacts to me. Maybe 
specks of light reflected off the green glass inside the lantern and 
then out through one of the holes?

If it wasn't for the render time I would suggest trying the same scene 
with the holes in the lantern patched up.

That said, using small emissive objects as illumination sources in 
radiosity scenes is a typical settings to get stray bright speckles; I 
would recommend making the flame object invisible to radiosity (using 
the no_radiosity keyword), and placing a regular light_source there.


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From: MichaelJF
Subject: Re: Question about radiosity
Date: 20 Nov 2013 17:15:01
Message: <web.528d33d8f97fc515a8a8fb540@news.povray.org>
clipka <ano### [at] anonymousorg> wrote:
> Am 20.11.2013 21:57, schrieb MichaelJF:
> > Seems the image was lost with my first posting.
>
> The artifacts don't look like typical radiosity artifacts to me. Maybe
> specks of light reflected off the green glass inside the lantern and
> then out through one of the holes?
>
> If it wasn't for the render time I would suggest trying the same scene
> with the holes in the lantern patched up.
>
> That said, using small emissive objects as illumination sources in
> radiosity scenes is a typical settings to get stray bright speckles; I
> would recommend making the flame object invisible to radiosity (using
> the no_radiosity keyword), and placing a regular light_source there.

Many thanks for your hints. Meanwhile I just started a second rendering with
higher radiosity settings and less brightness. Will see what happens first. May
it take four days... To close the gaps within the lantern would mean to dive in
an object laying around for more than four years at my "stalled" directories.
And my little lantern is not as simple a CSG object as it may look at first
sight. But to close the gaps should not be to complicated... I only would not
really like to do this, since they are there at the original. May be I just have
to fire it up and look at my garden wall. May be a snail passes by;-)

Best regards and thanks,
Michael


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