Hello,
I am new in POVand I will create a cylinder object and a conehole
inside of this cylinder. The surcace should be mirro-reflaxtion.

Here my POV-file:

// Persistence Of Vision raytracer version 3.0 sample file.

#version 3.0
global_settings { assumed_gamma 2.2 }

#include "colors.inc"
#include "textures.inc"
#include "metals.inc"
#include "glass.inc"
#include "stones.inc"
//#include "coords.pov"

#declare T14 = texture {finish {Mirror} pigment{White}}
#declare T03 = texture { pigment {DMFDarkOak}}
#declare T27 = texture {Polished_Chrome}

camera {

  location <200, 120, 100>
  //right <4/3, 0, 0>
  //up <0, 1, 0>
  //sky <0, 1, 0>
  direction <0, 0, 1.9>
  look_at <0, 0, 0>
}

light_source { <0, 100,100> colour White shadowless }
light_source { <0, 100,-100> colour White shadowless }
light_source { <120, 100,-100> colour White shadowless }

light_source { <0, 180, 0> colour White  }
light_source { <60, 10, 60> colour White  }

light_source {
    <2, 10, -3>
    color White
    area_light <5, 0, 0>, <0, 0, -50>, 50, 50
    adaptive 1
    jitter
  }

difference
{
    cylinder { <0, 0, 0>, <0, 40, 0>, 55 }
    cone { <0, 0, 0>, 10.0, <0, 40, 0>, 30.0 }
    texture { T_Stone25 scale 4 }
}

What is the mistake ?

If there anyone who will send me an email, here my e-mail address:
M.P### [at] t-onlinede


Many thanks.
Markus Pfaff
Germany

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Hi Markus!

I see two problems:
1. The end-surfaces of the cylinder and the cone are exactly the same.
Thats a problem for POV-Ray: Whenever two surfaces are exactly the same,
you can never be sure which one POV-Ray is going to use. After all a
pixel can only have one color: So POV-Ray decides arbitrarily to use the
color of the surface one or the surface two.
The same problem exists here with the CSG: When cutting the cone from
the cylinder, where the cone has exactly the same length as the cylinder
and the exact same orientation, only different radii, POV-Ray does not
know how you want to cut: Cut a hole or leaf an infinitely thin
covering?

> difference
> {
>     cylinder { <0, 0, 0>, <0, 40, 0>, 55 }
>     cone { <0, 0, 0>, 10.0, <0, 40, 0>, 30.0 }
>     texture { T_Stone25 scale 4 }
> }

Simply make your cone a little bit larger:
   cone { <0, -1, 0>, 10.0, <0, 41, 0>, 30.0 }

2. You have so many lights in the scene, and they ligth the scene so
evenly, that even with the corrected line from above it is very hard to
actually see the hole. No contrast at all. Imagine a studio-scene
lighted by an array of high powered spots from all directions. It would
have very little shadows and contrasts, making it difficult to make out
countors on the resulting 2D photo.
Use less lights with better positioning to get shadows and contrasts!

Hope it helps, Johannes.

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