[vtkusers] Polydata Normals, once again

[ftouvet]

Hello,

I am facing a strange problem concerning the normals of a polydata: there
are normals pointing both inside and outside!
The thing is that it is not an usual polydata, it is generated from a 360°
rotation of a contour on a plane. My guess is that it has not one but two
surfaces. I tried to change parameters of the different filters but no good
result came out; I also tried to recompute normals with vtkPolyDataNormals
but I always get my double set of normals.
My question now is: is it possible to delete a part of the normals? of the
mesh?

Here is a sample code to illustrate my question:

  plane = vtk.vtkPlane()
  plane.SetOrigin(0.0,0.0,0.0)
  plane.SetNormal(0.0, 1.0, 0.0)
  clipper = vtk.vtkClipPolyData()
  clipper.SetClipFunction(plane)
  clipper.InsideOutOn()
  clipper.SetInput(polyData)
  polyData=clipper.GetOutput()
  
  # rotational extrusion along z-direction
  extruder = vtk.vtkRotationalExtrusionFilter()
  extruder.SetAngle(360)
  extruder.SetInput(polyData)
  extruder.SetResolution(50)
  #extruder.SetCapping(1)
  polyData=extruder.GetOutput()


[0] http://docs.scipy.org/doc/numpy/reference/generated/numpy.mgrid.html



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