[vtkusers] vtkHedgeHog & vtkThresholdPoints

[Michael Bonner]

vtk users:

I have a set of vectors that I am visualizing with a vtkHedgeHog. I want to 
be able to remove vectors with norms less than or greater than a user 
specified value. I am trying to use a vtkThresholdPoints filter to modify 
the hedge hogs polydata output. I then set my actors input to the output of 
the vtkThresholdPoints obj.

I get this error when I call vtkRenderWindow->Interact():

vtkThresholdPoints.cxx, line 117 vtkThresholdPoints (0x0617C468): No scalar 
data to threshold

I do set the input polydata's point data scalars, and they are non-zero. It 
seems to me that the execution of the hedge hog does not preserve the scalars.

Is there a way to make this work, or a better way to do what I want?

Thanks
Mike Bonner