[vtkusers] Reducing the number of points in a vtkpolydata structure

[Amy Squillacote]

Hi Jens,

Try passing the output of vtkStreamPoints through the vtkMaskPoints 
filter before using vtkGlyph3D. The online documentation for that class 
is here: http://www.vtk.org/doc/nightly/html/classvtkMaskPoints.html.

- Amy

Jens Thomas wrote:
> Hello!
>
> I'm trying to experiment with flow lines, and so am trying to overlay 
> arrows onto streamlines.
>
> I can get this to work by creating streamlines with vtkStreamline, 
> then create a series of points with vtkStreampoints, and place arrows 
> on the points with vtkGlyph3d.
>
> This all works fine, but there are often far too many streampoints 
> produced and I'd like a quick and easy way of decreasing the number of 
> arrows - I'd prefer something simple as I'd like to include this 
> functionality in a GUI. I can of course recompute the streampoints 
> changing the IntegrationStepLength and TimeIncrement, but this seems 
> rather heavyweight as I've got all the data I need and just want to 
> sample a portion of it.
>
> Ideally, I'd just like to decrease the number of points in the 
> vtkPolyData produced by vtkStreamPoints.
>
> I've tried using vtkMaskPolyData, but this just changes the number of 
> cells and leaves the points unchanged.
>
> Is there any way I can change the number of points?
>
> Any suggestions would be greatly appreciated.
>
> Best wishes,
>
> Jens
>

-- 
Amy Squillacote
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065
Phone: (518) 371-3971 x106