[vtkusers] Unstructured grid to structured grid?

[David Gobbi]

Another filter that might work is vtkShepardMethod, which takes
unstructured points (e.g. an arbitrary set of samples) as input and
produces a vtkImageData as output.

The difference between vtkProbeFilter and vtkShepardMethod is
that the former performs the interpolation based on the connectivity
of the points (i.e. based on the cells), while the latter ignores the
connectivity and does the interpolation purely based on distance.

 - David

On Mon, Sep 15, 2014 at 4:23 PM, Chris Marsh <chris.marsh at usask.ca> wrote:
> Thanks David, this looks perfect.
>
>
> On Mon, Sep 15, 2014 at 4:10 PM, David Gobbi <david.gobbi at gmail.com> wrote:
>>
>> Hi Chris,
>>
>> This sounds like a job for vtkProbeFilter.  The probe filter takes two
>> inputs,
>> the "input" and the "source".  The idea is that it resamples the scalars
>> from
>> the "source" onto the geometry of the "input".  So, in this case, the
>> "source"
>> is your unstructured grid, and the "input" is any vtkImageData that has
>> the
>> origin, spacing, and extent that you want to use for the regridding.  The
>> output of vtkProbeFilter will be an image that has the same geometry as
>> the input, but that has pixel values that have been interpolated from your
>> unstructured grid.  You should be able to find several examples on the
>> wiki.
>>
>>  - David
>>
>>
>> On Mon, Sep 15, 2014 at 3:59 PM, chrism <chris.marsh at usask.ca> wrote:
>> > Is it possible to (easily) convert an unstructured grid to a structured
>> > grid
>> > (Image data)?
>> >
>> > Is unstructured -> polydata -> image data  the only way? If so, how
>> > example
>> > (http://www.vtk.org/Wiki/VTK/Examples/Cxx/PolyData/DataSetSurfaceFilter
>> > ??)
>> >
>> > Ultimately, the unstructured grid represents a topography, and I am
>> > looking
>> > to 'rasterize' it for use in a GIS.
>
>