[vtkusers] How to compute tangents and normals at each point of a curve ( vtkPolyData ) ???

[Deepak Roy]

 Hello,

-- I am using vtk 4.4.

-- I have a triangular surface mesh as input vtkPolyData

-- I intersect the surface with a cartesian plane ( xy , yz or xz ) and
obtain a curve --- i use the vtkContourFilter to extract this curve.

-- The curve thus extracted is in the form of vtkPolyData.

-- *Now how can I compute the curve normals and curve tangents at each point
on this curve ?*
**
    --- vtkPolyDataNormals filter does not work for curves according to the
documentation.

    --- Does anyone know if there is a VTK filter to achieve this task ?

    --- I tried computing the normals myself from the Lagrangian
Interpolation curve passing thru the point and its 1-neighbors.

    ------ But i faced one more problem - *How do i find the neighboring
vertices of a point  in vtkPolyData? *
**
    ----------- i tried vtkPolyData::GetPointCells() but this does not seem
to work for curves. Any ideas ????


Thanks in Advance.

Regards,

Deepak Roy
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