POV-Ray : Newsgroups : povray.general : Photons and reflections - huh? Server Time
1 Nov 2024 15:28:37 EDT (-0400)
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From: Severi Salminen
Subject: Photons and reflections - huh?
Date: 13 Sep 2004 08:23:04
Message: <41459128$1@news.povray.org>
Im probably missing something, but:

I have a red reflecting sphere and a white light source and a white 
plane and many photons. Should the light reflecting from the sphere 
(showing on the plane) be red, not white? Now it is white. I'd think 
that the red sphere should absorb all the other components but red. Or 
should it? So, is my thinking flawed or is this a feature/bug in 
POV-Ray's photon mapping? Most likely I'm missing something very obvious 
here so please correct me.

See the next scene:

camera {
     location  <1, 3, -2>
     look_at   <0, 0,  0>  }

light_source{<5,10,-5> rgb 1}

global_settings {photons { count 100000}}

plane {y,0 pigment {rgb 1} }

cylinder{0,y,1
     pigment {rgb x}
     finish {reflection 1}
     photons {target reflection on}
}


Regards,
Severi S


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From: Tim Nikias
Subject: Re: Photons and reflections - huh?
Date: 13 Sep 2004 08:48:03
Message: <41459703@news.povray.org>
I'm not quiet sure, but there is the possibility of adding a "metallic"
keyword inside the reflection-brackets. I guess that would take care of
photons being reflected with the correct color. You might want to look it up
in the Docs for further insight.

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

"Severi Salminen" <sev### [at] NOT_THISsibafi> schrieb im Newsbeitrag
news:41459128$1@news.povray.org...


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From: Severi Salminen
Subject: Re: Photons and reflections - huh?
Date: 13 Sep 2004 08:56:38
Message: <41459906$1@news.povray.org>
Tim Nikias wrote:

> I'm not quiet sure, but there is the possibility of adding a "metallic"
> keyword inside the reflection-brackets. I guess that would take care of
> photons being reflected with the correct color. You might want to look it up
> in the Docs for further insight.


"Metallic" didn't work as it only affects specular highlights. But 
thanks anyway!

Severi


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From: Slime
Subject: Re: Photons and reflections - huh?
Date: 13 Sep 2004 09:12:12
Message: <41459cac$1@news.povray.org>
>      pigment {rgb x}
>      finish {reflection 1}

Your sphere is red but reflects white light. If you want it to reflect red
light, use reflection <1,0,0>.

Or you can use finish {reflection {1 metallic}} (since "metallic" is inside
the "reflection" block, it will affect the reflection and not the specular
highlights).

 - Slime
 [ http://www.slimeland.com/ ]


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From: Severi Salminen
Subject: Re: Photons and reflections - huh?
Date: 13 Sep 2004 09:20:51
Message: <41459eb3@news.povray.org>
Slime wrote:

> Or you can use finish {reflection {1 metallic}} (since "metallic" is inside
> the "reflection" block, it will affect the reflection and not the specular
> highlights).

Oh, now I understand and that did it! Never knew there is a reflection 
block... :)

Severi


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From: Severi Salminen
Subject: Re: Photons and reflections - huh?
Date: 13 Sep 2004 09:21:30
Message: <41459eda$1@news.povray.org>
Severi Salminen wrote:

> "Metallic" didn't work as it only affects specular highlights. But 
> thanks anyway!

And if I specify it in reflection block it does work. So thank you 
again, anyway :)

Severi


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