POV-Ray

When using fade_distance and fade_power in combination with area_illumination, the light source fading is not applied to materials with subsurface scattering; see the following code for an example:

#version 3.7;
global_settings {
  assumed_gamma 1.0
  mm_per_unit 10
  subsurface { samples 200,20 }
}

camera {
  right x*image_width/image_height
  angle 30
  location  <0,1.5,-4>
  look_at   <0,0,0>
}

sky_sphere {
  pigment {
    gradient y
    color_map {
      [0.0 rgb <0.6,0.7,1.0>]
      [0.7 rgb <0.0,0.1,0.8>]
    }
  }
}

plane {
  y, 0
  texture {
    pigment {
      checker
      color rgb <1.0, 0.8, 0.6>
      color rgb <1.0, 0.0, 0.0>
      scale 0.5
    }
  }
}

light_source {
  <50,50,50>
  color rgb 30
  area_light 5*x,5*y,17,17 adaptive 1 jitter circular orient
  area_illumination on
  fade_distance 10
  fade_power 2
}

cylinder {
  <0,0,0>, <0,0.2,0> 1
  texture {
    pigment { color rgb 1 }
    finish {
      ambient 0
      diffuse 0.7
      specular albedo 0.3
      reflection { 0.3 fresnel }
      conserve_energy
      subsurface { translucency 0.1 }
    }
  }
  interior { ior 1.5 }
}

sphere {
  <0,0.4,0>, 0.2
  texture {
    pigment { color rgb <1,0.6,0.0> }
    finish {
      ambient 0
      diffuse 0.0
      specular albedo 0.8 metallic
      reflection { 1.0 metallic }
      conserve_energy
    }
  }
}