[vtkusers] Clipping accuracy

[Jonas Chapuis]

Hello all,

I'm trying to clip PolyData with a boolean implicit function. This 
function is a combination of two orthogonal planes. The result of the 
clipping is not accurate - this is especialy visible when cliping long 
triangles for instance.

I strongly suspect the cause of this problem is the way VTK determines 
the exact position of the intersection points on the edges of the 
polygons. It is linearly interpolated from the scalar values calculated 
for the two endpoints of the edge, and thus inexact in the case of an 
non-linear implicit function like mine.

Is there any workaround for this problem ? Would it be somehow posible 
to tell the Clip function of the cell how to determine the intersection 
point, not by interpolating, but by probing on the edges where the 
implicit function equals the clip isovalue (0 by default) ?

Thanks, regards,

jonas