Hi all, could someone run the code below and tell me if they see large
artifacts? A brief description of the problem, and the code is below:

Rendering scenes containing sphere sweep objects which are either very large
or very small leads to large artifacts. Different artifacts are seen
depending on the size of the object, and the type of spline used (linear,
cubic etc). A simple test scene is reproduced below.

The parameter 'myscale' scales the object and the cameras position
proportionally. For values of 'myscale' less then 0.01, and greater then
10, various artifacts are seen. The artifacts cannot be removed by varying
the value of 'tolerance'.

#include "colors.inc"

#declare num_phi1=10;
#declare myscale=0.01;

sphere_sweep {
    cubic_spline
    num_phi1+1,
    #declare _phi1 = 0;
    #while (_phi1<=6)
         #declare p1 =<sin(_phi1),-cos(_phi1),0>*myscale;
         p1,0.1*myscale
         #declare _phi1 = _phi1 + 6/num_phi1;
    #end
    tolerance 0.01
    pigment {Red}
}

background{White}

camera {
    angle 0
    location <0.0, 0, -1>*3*myscale
    look_at <0,0,0>
}

light_source { <0, 0, 0> color White }

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