[Paraview] Best way to plot arrows on a subsample of data?

[Moreland, Kenneth]

Jonathan,

 

It sounds like you want to sample an unstructured grid on a course
structured grid and then glyph that.  As far as I know, there is no
filter in ParaView that resamples an unstructured grid onto a structured
grid.  There are, however, at least a couple of filters in VTK that will
do so: vtkShepardMethod and vtkGaussianSplatter.  It's fairly
straightforward to make a plugin to ParaView that will make these
available under the Filters menu.  There are a couple of Wiki pages
outlining how to do this.

 

For ParaView 2: http://www.paraview.org/Wiki/ParaView:Extend

 

For ParaView 3: http://www.paraview.org/Wiki/Plugin_HowTo

 

I can also think of a way to do this resampling by repetitively using
the Cut filter (called Slice in ParaView 3).  If you look at the
parameters of this filter, you see a section called "Cut Offset Values"
("Slice Offset Values" in PV3).  This allows you to make a series of
cuts at regular intervals along a vector.  When you use this option on a
3D solid mesh, you get a series of planes.  If you apply the filter
again with the slice planes along a different vector, you get a
collection of lines.  Apply the filter a third time along yet another
vector and you get a collection of points, upon which you can apply the
glyph filter.

 

-Ken

 

________________________________

From: paraview-bounces+kmorel=sandia.gov at paraview.org
[mailto:paraview-bounces+kmorel=sandia.gov at paraview.org] On Behalf Of
Jonathan Hannay
Sent: Monday, July 02, 2007 3:13 PM
To: paraview at paraview.org
Subject: [Paraview] Best way to plot arrows on a subsample of data?

 

Hi,

I have a large amount of point data on an unstructured mesh.

 

How can I plot the vectors on a nice regular coarse sub-sample of the
underlying point data.

 

The options in the glyph filter using random and maximum points does not
give the points on a regularly shaped mesh which is what I want.

 

For example I may have a 1000x1000 square rectangle made up from an
unstructured grid with varying element sizes.

 

Now I would like to plot say just a 10x10 vector arrow plot on the
surface with uniform spacing.

 

I have tried a few things and have been unsuccessful.

 

Thanks for any help.

 

Jonathan.

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