Michael Freytag mkfreytag at
Mon Aug 23 11:27:22 EDT 1999

I have been using the vtkClipPolyData filter to clip visualization
geometry (iso-surfaces, streamlines, surfaces, etc. ) using implicit
functions.  I believe, perhaps incorrectly, that scalar values generated
by the implicit function at the vertices are the only data used within
the clip methods for the underlying geometry primitives.  The clip
point/(line) is found by linear interpolation from vertex values.

My situation:  The implicit functions I am using do not generate
linearly varying values but otherwise produce a distinct intersection.
Because of the linear interpolation algorithm used, my clipped geometry
output is unfortunately, not accurate.

My questions:
1- Are there clip methods that use the implicit function itself to find
the clip point/(line) for the geometry primitives by recursive
subdivision or some other estimation means?
2- Has anyone done this before?
3- Does anyone know of any commercial packages that implement this?

Thank you,
Michael Freytag

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