POV-Ray

Attached to Project: POV-Ray
Opened by Christoph Lipka - 2013-02-22
Last edited by William F Pokorny - 2016-11-16

The following scene has four spheres with different pigment color & filter settings:

- Left: filter 1
- Right: filter 0

- Top: red 0.0 green 0.5 blue 1.0
- Bottom: red 0.00 green 0.05 blue 0.10 (10% of the above)

Background is set to black, so that we only see the diffuse component of the object’s effective color.

Theoretically, both left spheres should be invisible, as they are fully transmissive (with a filtering effect), but apparently with a high filter setting, reducing an object’s pigment color actually increases the object’s effective diffuse color.

//+w600 +h600

global_settings{ assumed_gamma 1.0 }

camera {
  orthographic
  location  <0,0,-10>
  right 4*x
  up 4*y
  look_at   <0,0,0>
}

light_source{<10,10,-10> color rgb 1 parallel }

background { color rgb 0 }

default {
  finish {
    ambient 0
    diffuse 1
    specular 0
    phong 0
    reflection { 0.0 }
  }
}


sphere { <-1, 1, 0>, 0.8 texture { pigment { color rgb <0,0.5,1.0> filter 1.0 } } }
sphere { < 1, 1, 0>, 0.8 texture { pigment { color rgb <0,0.5,1.0> filter 0.0 } } }

sphere { <-1,-1, 0>, 0.8 texture { pigment { color rgb <0,0.5,1.0>*0.1 filter 1.0 } } }
sphere { < 1,-1, 0>, 0.8 texture { pigment { color rgb <0,0.5,1.0>*0.1 filter 0.0 } } }

This bug has been around in 3.6 already.