[vtkusers] Unstructured grid to structured grid?

Chris Marsh chris.marsh at usask.ca
Wed Sep 17 14:49:45 EDT 2014

Hi all,

Thanks for persevering with me. I got it working correctly with

The problem ended up being a PEBKAC with how I was using the Delaunay2D
class: When converting from CGAL to vtkUnstructuredgrid, you need to index
the face values and vertices separately while maintaining connectivity.
Because you are defining the connectivity, this works. However! with
vtkDelaunay2D, you can't do this. Rather, for each vertex that is added to
'points', the face data must be added 3-times. Which this isn't quite
perfect, it should work fine, unless there is a way of using an
unstructured mesh and a probe filter?
http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/GeometryFilter   suggests
you can? So I will have to play around with that more.

Thanks again, much appreciated.

Chris Marsh
PhD Student

13 Kirk Hall
University of Saskatchewan

On Wed, Sep 17, 2014 at 11:00 AM, David Gobbi <david.gobbi at gmail.com> wrote:

> On Wed, Sep 17, 2014 at 10:45 AM, Chris Marsh <chris.marsh at usask.ca>
> wrote:
> > Hi David,
> >
> > Thanks for the reply, this is slowly starting to make sense. That call
> did
> > in fact fix the bounds issues. However, the output still looks like it
> did
> > in the above screenshot.
> >
> >>The plane is already composed of cells, so you should not run it
> > through Delaunay.
> >
> > This is what perplexed me about the above linked example.
> >
> > What is the best way to write the probe results to a file then?
> At the beginning, I was hinting that you should probe with a
> vtkImageData, which you could have written out as an image
> (either as raw data, or as a png, etc).  But now that you have
> the probed data as a polydata plane, you'll have to get the
> scalars that are associated with the points that make up the
> polydata.  GetPointData()->GetScalars() will return an array
> that contains all the scalars.  See the VTK text for an in-depth
> description of how data is stored in a VTK data set.
>  - David
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