Hoi,

When I join a cylinder and a box I see odd light artifacts.
Is this a bug or am I misunderstanding something?

The following scene shows a close-up of the artifact.  The whole scene
consists of a box on top of a cylinder on top of another box.  At the
point where the cylinder and the box meet one can see the light shine
through. (The light green line)
The cylinder sticks about halfway into the box.

The artifact also shows when the union is removed.

The artifact dissapears however when the bottom box is removed
or when the union is replaced with a merge.

Have fun,
Frans.

----artifact.pov-----------------------------------------------
// close-up view
camera { location  <0.5, 1.59, 0.5> look_at <0, 2, 0>}

// Try this for an overview
// camera { location  <0.5, 2.59, -4.5> look_at <0, 2, 0>}

light_source {<1,10,1> colour rgb 1}
light_source {<1.1,10,1> colour rgb 1}
light_source {<1,10,1.1> colour rgb 1}

union {
  box {
     <0,1.8,0>
     <4,2.1,4>
     finish {specular 0.2}
     pigment { colour rgb <1,0,0> }
  }

  cylinder {
     -1*y,  2*y,  0.44
     finish {specular 0.2}
     pigment {color rgb <0, 1, 0>}
  }

  box {
    <0,0,0>
    <4,0.1,4>
    translate <-2,-1,-2>
    finish {specular 0.2}
    pigment { colour rgb <0,1,1> }
  }
}

Post a reply to this message

Wasn't it gumpu who wrote:
>Hoi,
>
>When I join a cylinder and a box I see odd light artifacts.
>Is this a bug or am I misunderstanding something?

I don't know if it's a bug, but I can find a workround. Switch lighting
buffers off (-UL in the command line).

-- 
Mike Williams
Gentleman of Leisure

Post a reply to this message

Hi 'gumpu' Frans,

I had to add some ambient to the finishes and look more closely to see
the artifact, but now I recognize it as an effect that has also occurred
to me: see my threads in povray.general

   11th Feb. 2003   Small is NOT BEAUTIFUL,
    3rd Sept.2002   Intersection with quartic: bug?

and look at the accompanying pictures in povray.binaries.images.

The reason for such artifacts is some 'Epsilon' for creation of a little
overlap at the edges of objects and intersections to avoid looking
through corners. But the value of this 'Epsilon' has increased by
a couple of magnitudes with version 3.5. In my opinion, this is a bug.
The easiest way to make these artifacts invisible is to use larger
objects.


   Sputnik

--
-------------------------------------

e-mail: fr### [at] computermuseumfh-kielde
-------------------------------------

Post a reply to this message

Thanks for both suggestions... problem fixed :)

I was using this construction (box - cylinder) in a much more
complex scene and the artifact showed up rather badly when
I rendered a poster size version of this scene for Zazzle.

Have fun,
Frans.

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