Set here the numerical tolerances used to calculate coordination polyhedra.
Values too large may result in numerical inaccuracies.
Visible
When the mix product of four vertices (defining a face and a new vertex),
is larger than 
Visible the face is visible from the vertex and 
must be replaced. Increasing 
Visible may reduce face reconstruction,
but may result in numerical inaccuracies. The whole calculation is very 
sensitive to this parameter, so it should be handled carefully. Currently
the maximum allowed value is 
1.0E-5.
For complex systems, where different faces have almost the same orientation,
forming curved surfaces, setting 
Visible to 
0 might eliminate
numerical errors.
Coplanar
The initial triangle faces are merged when the mix product
of four vertices (belonging to both faces) is smaller than 
Coplanar. Increasing 
Coplanar promotes face merging, 
but may result in numerical inaccuracies. Currently the maximum
allowed value is 
1.0E-1.
Setting 
Coplanar to 
0 disables face merging,
so all faces will be triangles.