I've run into this problem: When we're modelling a tranparent object and place it on another surface (a floor, a table etc.) we get an ugly effect. The bottom surface of the transparent object will have the same y-value as the surface that the object is placed on. Is this something POV don't like? As an example I've included a minimalistic POV file with a "floor" and a simple transparent object. As you'll see the bottom surface of the transparent object goes ape (since it lies in the same plane as the "floor"?). Can someone explain to me why this happens?

Thanks!

-Rune

The .pov file:
========

global_settings
{
   assumed_gamma 2.2
   ambient_light 0.8
}

background { color rgb <0.9, 0.9, 0.9> }

camera
{
   location <100, 100, 100>
   angle 18
   look_at  <0,5,0>
}

light_source { <250, 200, -100> color 1.5 }

// Floor
#declare T1 = texture
{
  pigment { rgb <.5, .5, .9> }
  finish { ambient 0.70 diffuse 0.70 }
}
mesh
{
  smooth_triangle
  {
    <-500, 0,  500>, <0,1,0>
    < 500, 0,  500>, <0,1,0>
    <   0, 0, -500>, <0,1,0>
  }
  texture {T1}
}

// Transparent object
#declare T2 = texture
{
  pigment { rgbt <.6, .6, .6, 0.90> }
  finish { ambient 0.5 diffuse 1.0 }
}
mesh
{
  smooth_triangle
  {
    <-10, 0,   5> <0, -1, 0>
    <  0, 0, -10> <0, -1, 0>
    < 10, 0,   5> <0, -1, 0>
  }
  smooth_triangle
  {
    <-10,  0,   5> <0, .6, .8>
    < 10,  0,   5> <0, .6, .8>
    <  0, 20,   0> <0, .6, .8>
  }
  smooth_triangle
  {
    < 10,  0,   5> <0.4,0.82,-0.4>
    <  0,  0, -10> <0.4,0.82,-0.4>
    <  0, 20,   0> <0.4,0.82,-0.4>
  }
  smooth_triangle
  {
    <  0,  0, -10> <-0.4,0.82,-0.4>
    <-10,  0,   5> <-0.4,0.82,-0.4>
    <  0, 20,   0> <-0.4,0.82,-0.4>
  }
 texture {T2}
}

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