[vtkusers] Help on selecting voxels inside a vtkImplicitFunction

[David E DeMarle]

In general the output of this type of operation has to be either
vtkUnstructuredGrid or vtkPolyData because when you take an arbitrary subset
out of a structured data set you loose the regularity.

vtkExtractVOI pulls out aligned "slabs" out of structured datasets and
because the slabs are aligned in ijk space it's output can stay structured.

If you have to keep it structured your only option is to create an
inside/outside data array. You can threshold on that later if you need to,
but again that will produce an unstructured dataset. I think vtkProbeFilter
and vtkSampleFunction both can be used to create the "insidedness" array.
Others options likely exist too.

David E DeMarle
Kitware, Inc.
R&D Engineer
28 Corporate Drive
Clifton Park, NY 12065-8662
Phone: 518-371-3971 x109


On Sat, Sep 19, 2009 at 10:13 AM, Robin Zhao <zhaoyoubing at gmail.com> wrote:

> Hi, Dear vtk guys,
>
> I met some difficulties on selecting voxels inside a user defined implicit
> function.
>
> I have studied vtkExtractGeometry, but its output is unstructured grid.
>
> I also studied vtkSelection which seems not to support vtkImplicitFunction.
>
> Are there any possible methods to do it in the framework of vtk,
> or do I need to do it by myself.
>
> Cheers
>
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