Hi there,

The minimal scene file below should produce identical images for any 
value of the scaling factor s, but it doesn't. s=1e-1 works fine, s=1e-3 
produces individual spheres instead of a sweep, and s=1e-5 makes the 
object fully invisible. The code for sphere_sweep doesn't seem to scale.

Using other values for the sphere_sweep tolerance and turning off the 
bounding (-MB) doesn't solve the problem.

This might be related to http://bugs.povray.org/task/81, as I'm getting 
the artifacts described there as well for intermediate scaling factors, 
but the problems described here appear to be much more severe.

I'm using POV-Ray 3.7 on OpenSUSE 12.2.

Regards,
Roman



// START MINIMAL SCENE FILE

#version 3.7;

#declare s = 1e-3; // 1e-1: ok, 1e-3: individual spheres, 1e-5: invisible

camera {
	location 7*z
	look_at 0
	scale s
}

light_source {
	<20,25,40>, rgb 1
	scale s
}

sphere_sweep {
	cubic_spline
	5,
	< 2.4,-2.1,0>, 1
	< 0.8,-0.9,0>, 1
	<-0.6, 0.4,0>, 1
	<-1.8, 1.7,0>, 1
	<-2.8, 2.0,0>, 1
	scale s
	pigment { color rgb 1 }
}

// END MINIMAL SCENE FILE

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Attachments:
Download 'sphere_sweep_problem_1e-1.png' (3 KB) Download 'sphere_sweep_problem_1e-3.png' (3 KB) Download 'sphere_sweep_problem_1e-5.png' (1 KB)

Preview of image 'sphere_sweep_problem_1e-1.png'

Preview of image 'sphere_sweep_problem_1e-3.png'

Preview of image 'sphere_sweep_problem_1e-5.png'