"David Mandelberg" <dav### [at] mandelbergorg> wrote:
> When I render the below scene, there are some spurious black artifacts near the
> center of the red vuvuzela. Without the translation and rotation, the artifacts
> go away.

I'm not sure how you got them to go away - they certainly don't for me.

I've tried removing the translation and rotation, and moving the camera, the
light sources, etc.  Gave the finish a little specular reflection - still there.
I used a cubic_spline instead - still there.

I suppose I ought to mention that when i was deveoping a recent scene with a
bell - I used a SOR, and I saw the same sort of artefact.

<snippet>
#declare bellSpline = array [12] {
     < 3.4688, 0.0001>,
     < 3.4688, 0.0002>,
     < 3.0938, 0.4375>,
     < 2.9375, 0.6250>,
     < 2.4844, 1.3438>,
     < 2.1719, 2.6094>,
     < 2.0469, 4.4688>,
     < 1.9063, 4.6875>,
     < 1.7500, 4.8750>,
     < 1.0313, 5.0938>,
     < 0.0001, 5.1563>,
     < 0.0001, 5.1564>
}

.....


#declare Bell1 =
union {

 cylinder {<0, 0, 0>, <0, (5.0938/2)+1, 0> 0.125}
 sphere {0, 0.25}
 torus {0.125, 0.125/4 rotate x*90 translate -y*0.25}
 object {Handle translate -y*1}
 sor {
     arraySize+1,
  #for (B, 0, arraySize)
  #local NewSpline = bellSpline [B]/2;
  //#debug concat ("B = ", str (B, 3, 1), "| Point = ", vstr (2, bellSpline [B],
",", 5, 1), "\n")
  #declare Xmax = max (Xmax, NewSpline.x);
  #declare Ymax = max (Ymax, NewSpline.y);
  NewSpline,
  #end
     open
 }
 //texture { T_Gold_1B }
 texture { mtex }
 //pigment {rgb <1, 1, 0>}
}

</snippet>

So there's something going on - just in general.

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