[vtkusers] Fwd: Unsure how to use vtkDelaunay3D

[vtk matt]

Hi David,

Thanks for the clarification.  I
ran tets->GetOutput()->GetNumberOfElements(vtkDataObject::CELL) and got a
value of 18 for my input which would make sense as the number of
tetrahedrons.  Do you know if I can expect these cells to in fact contain
tetrahedrons then?

--Matt

On Wed, May 27, 2015 at 8:17 PM, David Gobbi <david.gobbi at gmail.com> wrote:

> Hi Matt,
>
> You've been misled by VTK's rather terse documentation:
>
>   Get the number of elements for a specific attribute type (POINT, CELL,
> etc.).
>
> For a mesh, you can call GetNumberOfElements(vtkDataObject::POINT) or you
> can call GetNumberOfElements(vtkDataObject::CELL).  Those are the only two
> choices.  You can't ask for a particular type of cell, all you can do is
> ask it to return the total number of cells.
>
>  - David
>
> On Wed, May 27, 2015 at 5:41 PM, vtk matt <vtkmatt at gmail.com> wrote:
>
>> Hi all,
>>
>> I have spent the past few days trying to figure out how to use
>> vtkDelaunay3D properly and decided I'd better seek out some help.  My goal
>> is relatively straight-forward:  Given a set of points in 3D, generate a
>> tetrahedral mesh, and use the results to determine which tetrahedron
>> contains an arbitrary point.
>>
>> In its simplest form I am doing the following:
>>
>> vtkSmartPointer<vtkDelaunay3D> tets =
>> vtkSmartPointer<vtkDelaunay3D>::New();
>> tets->SetInput(points);
>> tets->Update();
>> printf("Number of tets: %d\n",
>> tets->GetOutput()->GetNumberOfElements(VTK_TETRA));
>>
>> The output claims there are zero tetrahedrons.  However if I render an
>> actor from tets->GetOutput(), I am able to visualize a wireframe surface
>> mesh, so I know it's doing something.
>>
>> So I guess my questions are the following:  Why does the output not
>> contain any tetrahedrons?  Why does the mesh only show surface triangles?
>> Ultimately what is the proper way to construct a tetrahedral mesh such that
>> I can query which tetrahedron contains an arbitrary point?
>>
>> Thanks.
>>
>> --Matt
>>
>
>
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