POV-Ray : Newsgroups : povray.general : scattering media and light groups bug? Server Time
4 Aug 2024 08:25:56 EDT (-0400)
  scattering media and light groups bug? (Message 1 to 2 of 2)  
From: Mark Weyer
Subject: scattering media and light groups bug?
Date: 30 Jun 2003 12:51:14
Message: <3F006AE6.2000305@informatik.uni-freiburg.de>
When I have scattering media inside object A (box below) and inside
that object there is some portion of another object B (plane below),
it seems as though that portion is lighted oddly. One explanation
might be that rays from there to the light source ignore light_group
issues.

Minimal scene below. The bright spot on the bottom of the box is
what I do not understand. The darkish look of the box itself is just
extinction. Anyway, I am not happy with that bright spot. Is this a
bug or my fault? How do I change the scene to get what I want? (Well
I know that for this minimal scene, absorption 1 would do the trick,
but for the non-minimal one I have in mind I really need scattering)


camera {
   right x
   up y
   direction z
   location -10*z
   rotate 20*x
}

light_source {<-1,1,-1>*100 1}

plane {
   y (-1)
   pigment {
     checker
     rgb 1
     rgb 0
   }
}

light_group {
   box {-2 2
     pigment {transmit 1}
     no_shadow
     hollow
     interior {
       media {
         scattering {1, 1}
       }
     }
   }
   global_lights off
}


-- 
merge{#local i=-11;#while(i<11)#local
i=i+.1;sphere{<i*(i*i*(.05-i*i*(4e-7*i*i+3e-4))-3)10*sin(i)30>.5}#end
pigment{rgbt 1}interior{media{emission x}}hollow}//  Mark Weyer


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From: Mark Weyer
Subject: Re: scattering media and light groups bug?
Date: 1 Jul 2003 04:47:52
Message: <3F014B23.7070200@informatik.uni-freiburg.de>
> One explanation
> might be that rays from there to the light source ignore light_group
> issues.

On a second thought: That explanation would imply that rays from a
surface to a light_source are brightened by scattering media, which
is not true and should not be true.


-- 
merge{#local i=-11;#while(i<11)#local
i=i+.1;sphere{<i*(i*i*(.05-i*i*(4e-7*i*i+3e-4))-3)10*sin(i)30>.5}#end
pigment{rgbt 1}interior{media{emission x}}hollow}//  Mark Weyer


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