[vtkusers] Thresholding a vtkStructuredGrid -> vtkUnstructuredGrid?

[Thomas Deschamps]

Hi vtkUsers,

I have a vtkStructuredGrid containing the components of a vector field 
that I represent by means of vtkGlyph3D.
In fact this is a representation of the gradient components of the image 
at each pixel.

The problem is that I have big images and I would like to remove the 
vectors with small gradient magnitude from the final visualization.
In fact I have so many vectors that sometimes my graphic card can't 
stand it and the computer reboots...

Rather than using vtkExtractGrid which uses a regular sampling rate, I 
would like to choose which vectors are removed, based on my criterion.
And I would like to still use vtkGlyph3D to represent the resulting 
vector field.

So I would like to know if there is a simple way to do that, or if there 
isn't.
Anyway thanks for reading this email.

Thomas (tdeschamps at lbl.gov)