POV-Ray : Newsgroups : povray.binaries.images : Photon problem Server Time
15 Nov 2024 16:14:54 EST (-0500)
  Photon problem (Message 1 to 3 of 3)  
From: Gilles Tran
Subject: Photon problem
Date: 13 May 2003 05:06:24
Message: <3ec0b590@news.povray.org>
See the attached pic below.
The green beam bounces correctly from the reflective box, but what's going
on with the red one?
Am I missing something obvious? The only difference between the two cylinder
lights is their point_at value. Other tests show erratic behaviour:
sometimes the beam doesn't bounce at all, sometimes it bounces from another
part of the surface (higher or lower).

background{rgb z}
global_settings {photons {count 20000 media 100}}
light_source{<5,0.1,0>, rgb y*2 cylinder radius 0.2 falloff 0.4 point_at
<0,5,0>} // OK
light_source{<5,0.1,0>, rgb x*2 cylinder radius 0.2 falloff 0.4 point_at
<2,5,0>} // Not oK
box{<-2,0,-2>,<2,10,2> texture{pigment{rgb 0.1}finish{ambient 0 diffuse 0.4
reflection 0.8}}
    photons{target reflection on refraction off collect off}
}
box{<-2,-0.1,-2>,<2,10,2> scale 10
    texture{pigment{rgbf 1}} hollow
    interior{media{scattering {1,1 extinction 0}}}
}
camera{location <0,6,-20>   right 1.33*x   angle 50   look_at 4*y
   rotate y*-20
}


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Attachments:
Download 'beam.jpg' (9 KB)

Preview of image 'beam.jpg'
beam.jpg


 

From: ABX
Subject: Re: Photon problem
Date: 13 May 2003 05:16:10
Message: <jod1cv8mf1kk35fhc2jd1tl7j9gknodvkv@4ax.com>
On Tue, 13 May 2003 11:10:52 +0200, "Gilles Tran" <tra### [at] inapginrafr> wrote:
> See the attached pic below.

I have no idea what happens but for you knowledge I can confirm it works the
same with newest source code.

ABX


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From: Gilles Tran
Subject: Re: Photon problem
Date: 13 May 2003 11:01:59
Message: <3ec108e7$1@news.povray.org>

jod1cv8mf1kk35fhc2jd1tl7j9gknodvkv@4ax.com...

> I have no idea what happens but for you knowledge I can confirm it works
the
> same with newest source code.

In Nathan Kopp's Megapov page, it is said that photons do not work properly
with cylinder lights (the light beam is not confined to the cylinder).
Apparently this limitation (which is not reported in the current docs) is
still in 3.5. Regular spotlights do not present this limitation but
unfortunately this is not the effect I was looking for :(
I still have alternative solutions to explore though.

G.
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http://www.oyonale.com
**********************
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