POV-Ray : Newsgroups : povray.binaries.images : Can't get photons to bring about desired refraction Server Time
25 Dec 2024 01:39:08 EST (-0500)
  Can't get photons to bring about desired refraction (Message 1 to 4 of 4)  
From: CFM
Subject: Can't get photons to bring about desired refraction
Date: 6 May 2004 14:20:00
Message: <web.409a8149d855a4115c168f750@news.povray.org>
Here's the programming language used to render the image I'm posting. Notice
there are no rainbow-style effects refracting onto the ground. How do I get
proper refraction?

#include "colors.inc"
#include "textures.inc"
#include "finish.inc"
#include "glass.inc"
global_settings {
  max_trace_level 12
  photons {
    count 100000
    spacing .01
    autostop 0
    jitter .2
  }
}
camera {
  location <0,7.5,-10>
  look_at 0
}
light_source {<1000,1000,-1000>rgb<1,1,1>
  photons {refraction on
           reflection on}
}
background {rgb<.7,.7,1>}
plane {<0,1,0>,-1
  pigment {rgb<.5,.5,.5>
  }
  finish {ambient 1}
  photons {collect off}
}
sphere {<5,1,0>,2
  texture {T_Old_Glass}
  finish {ambient 0
          diffuse .5
          reflection .25
} interior {ior 1.5
            dispersion 1
            caustics .25
            fade_distance .25
            fade_power .25}
  photons {
    target 1
    refraction on
    reflection off
}
cylinder {<-3,0,0>,<-3,4,0>,1
  texture {T_Old_Glass}
  finish {ambient 0
          diffuse .5
          reflection .25}
  interior {ior 1.5
            dispersion 1.1
            caustics .25
            fade_distance .25
            fade_power .25
  photons {target 1
           refraction on
           reflection off
  }
}


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Attachments:
Download 'prism problem.jpg' (10 KB)

Preview of image 'prism problem.jpg'
prism problem.jpg


 

From: Steven Pigeon
Subject: Re: Can't get photons to bring about desired refraction
Date: 6 May 2004 15:54:37
Message: <409a97fd$1@news.povray.org>
Maybe your fade distance in your
interior is too small. Try fade distance
1.0, or more. A "natural" fade power
is 2.0, as in real life: intensity is inversely
proportionnal to the square of the distance.


Also, I think count and spacing are mutually
exclusive. I do not know which one "wins"
when both are specified.

Best,

    S.

"CFM" <nomail@nomail> wrote in message
news:web.409a8149d855a4115c168f750@news.povray.org...
> Here's the programming language used to render the image I'm posting.
Notice
> there are no rainbow-style effects refracting onto the ground. How do I
get
> proper refraction?
>
> #include "colors.inc"
> #include "textures.inc"
> #include "finish.inc"
> #include "glass.inc"
> global_settings {
>   max_trace_level 12
>   photons {
>     count 100000
>     spacing .01
>     autostop 0
>     jitter .2
>   }
> }
> camera {
>   location <0,7.5,-10>
>   look_at 0
> }
> light_source {<1000,1000,-1000>rgb<1,1,1>
>   photons {refraction on
>            reflection on}
> }
> background {rgb<.7,.7,1>}
> plane {<0,1,0>,-1
>   pigment {rgb<.5,.5,.5>
>   }
>   finish {ambient 1}
>   photons {collect off}
> }
> sphere {<5,1,0>,2
>   texture {T_Old_Glass}
>   finish {ambient 0
>           diffuse .5
>           reflection .25
> } interior {ior 1.5
>             dispersion 1
>             caustics .25
>             fade_distance .25
>             fade_power .25}
>   photons {
>     target 1
>     refraction on
>     reflection off
> }
> cylinder {<-3,0,0>,<-3,4,0>,1
>   texture {T_Old_Glass}
>   finish {ambient 0
>           diffuse .5
>           reflection .25}
>   interior {ior 1.5
>             dispersion 1.1
>             caustics .25
>             fade_distance .25
>             fade_power .25
>   photons {target 1
>            refraction on
>            reflection off
>   }
> }
>


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----


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From: Tim Nikias v2 0
Subject: Re: Can't get photons to bring about desired refraction
Date: 6 May 2004 17:31:15
Message: <409aaea3$1@news.povray.org>
And, if I'm not mistaken, dispersion should be >1 to produce any kind of
rainbow-effect, try using 1.01 or such.

Regards,
Tim

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


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From: Alain
Subject: Re: Can't get photons to bring about desired refraction
Date: 6 May 2004 18:38:08
Message: <409abe50@news.povray.org>
Tim Nikias v2.0 nous apporta ses lumieres ainsi en ce 2004/05/06 18:25... :

>And, if I'm not mistaken, dispersion should be >1 to produce any kind of
>rainbow-effect, try using 1.01 or such.
>
>Regards,
>Tim
>
>  
>
The sphere have distersion=1 and the cylinder have dispersion=1.1. 
"Natural" value goes from >1 to 1.1, but you can use about any value 
!=1, even negative if you want.
Try using  "dispersion_samples" with a value greater than the default of 7
||
Alain


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