Qfyd nous apporta ses lumieres en ce 2005-01-19 08:00:
> I'm currently trying to get a sphere sweep approximation of my 
> signiature and for some reason the object produced is full of tiny holes.
> 
> I've looked at all the info about self-shadowing and tolerance but no 
> matter how I set the tolerance, the sweep looks like it's 
> disintegrating. Besides, this isn't self shadowing as far as I can tell, 
> the missing parts aren't just dark, they're transparent.
> 
> 
> //This is the code I'm working with
> global_settings{assumed_gamma 1.2}
> camera {orthographic location<0,0,-5> look_at<0,0,0>}
> 
> light_source{<0,0,-30> color rgb 2}
> 
> sphere_sweep {
>  b_spline
>  10
>  <-1.5,1,0>,0.03
>  <0,1,0>,0.03
>  <1,1,0>,0.03
>  <1.4,1.2,0>,0.03
>  <1.2,1.4,0>,0.03
>  <1,1.2,0>,0.03
>  <1,-1,0>,0.03
>  <1.03,-1.03,0>,0.03
>  <1.06,0,0>,0.03
>  <2,0,0>,0.03
>  //tolerance 1.0e-6
>  pigment{color rgb <1,0,0>}
>  finish{phong 1}
>  translate<-2,0,0>
> }
> //end code fragment
> 
> Any ideas?
> 
> -Pete
It hit me also on another image. It was a sweep thru a bunch of random 3D coordinates.
A rotate 1 get rid of all artefacts. Changing the tolerance _may_ reduce them, but
don't remove 
them. Even a tolerance set to 5 did nothing.
It looks like it depend on the curvature (maybe) and the angle at whitch the ray from
the camera 
meet the sphere_sweep.
It looks like a bug to me.

Alain

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