[vtk-developers] Number of neighbours for each cell
Will Schroeder
will.schroeder at kitware.com
Fri Jul 22 08:51:58 EDT 2016
Sure send the image we always love a challenge :-) Obviously if it becomes
more involved we can talk about a support product
<http://www.kitware.com/products/support.html>, etc.
Best,
W
On Fri, Jul 22, 2016 at 8:44 AM, Lodron, Gerald <Gerald.Lodron at joanneum.at>
wrote:
> Cool
>
>
>
> For my first test that implementation below worked and i found out that
> this kind of algorithm does not help me on my problem, arg
>
>
>
> Can I send you an image/screenshot of the “geometric” stuff I want to
> filter? May you as an expert has a better idea for solving my problem.
> Short text description (but is really hard to explain):
>
>
>
> I have a mesh of a surface, scanned with a 3d scanner (triangles,
> vtkPolydata as explained). On the border of that mesh I have single “noisy”
> (or fringy) structures which I want to filter. These noise structures are
> minimal connected to the main mesh, so I can not use connected component
> filter (which I also used apriory to remove noise in the air).
>
>
>
> *Von:* Will Schroeder [mailto:will.schroeder at kitware.com]
> *Gesend**et:* Freitag, 22. Juli 2016 14:37
>
> *An:* Lodron, Gerald
> *Cc:* VTK Developer (vtk-developers at vtk.org)
> *Betreff:* Re: [vtk-developers] Number of neighbours for each cell
>
>
>
> Yes this is a great start. Since I am on a performance kick, I would
> probably use (under the hood) vtkStaticCellLocator which builds the links
> between points and cells much faster (threaded using vtkSMPTools and a
> parallel sort). The actual "counting" of the neighbors could then be sped
> up using vtkSMPTools as well. It's probably overkill, but I'd like VTK to
> knock off the socks of anyone using it, and also to support our HPC friends
> who have this humbling habit of dumping really big data on top of VTK :-)
>
>
>
> Best,
> W
>
>
>
> On Fri, Jul 22, 2016 at 8:25 AM, Lodron, Gerald <Gerald.Lodron at joanneum.at>
> wrote:
>
> In my case the definition would be an edge, but yes it would be useful to
> define that as parameter….
>
> I already found a maybe not beautiful algorithm for vertices, not edges,
> may you want to reuse it as initial code:
>
> vtkSmartPointer<vtkUnsignedIntArray> neighbours =
> vtkSmartPointer<vtkUnsignedIntArray>::New();
> neighbours ->SetName("NumberOfNeighbours");
> neighbours ->SetNumberOfValues(numberOfCells);
>
> vtkSmartPointer<vtkIdList> cellPointIds =
> vtkSmartPointer<vtkIdList>::New();
>
> vtkSmartPointer<vtkIdList> ptids =
> vtkSmartPointer<vtkIdList>::New();
> vtkSmartPointer<vtkIdList> cellids =
> vtkSmartPointer<vtkIdList>::New();
>
> for (vtkIdType cellId = 0; cellId < numberOfCells; ++cellId)
> {
> input->GetCellPoints(cellId, ptids);
> /*
> does not work
> input ->GetCellNeighbors(cellId, oPtIds, oCellIds);
> neighbours ->SetValue(cellId, static_cast<unsigned
> int>(oCellIds->GetNumberOfIds()));*/
> std::set<vtkIdType> id_set;
>
> for (vtkIdType ptid = 0; ptid < ptids
> ->GetNumberOfIds();ptid++)
> {
> poInput1->GetPointCells(ptids ->GetId(ptid), cellids);
> for (vtkIdType cid = 0; cid < cellids
> ->GetNumberOfIds();cid++)
> {
> vtkIdType id = cellids ->GetId(cid);
> if (id != cellId)
> {
> id_set.insert(cellids->GetId(cid));
> }
> }
> }
> neighbours ->SetValue(cellId, static_cast<unsigned int>(
> id_set.size()));
> }
> output->GetCellData()->AddArray(neighbours);
>
> Von: Will Schroeder [mailto:will.schroeder at kitware.com]
> Gesendet: Freitag, 22. Juli 2016 14:09
> An: Lodron, Gerald
> Cc: VTK Developer (vtk-developers at vtk.org)
> Betreff: Re: [vtk-developers] Number of neighbours for each cell
>
>
> I don't know of such a filter but it would be easy to put together.
> Certainly it would be another useful tool in the topological analysis
> toolbox.
>
> Question: what is your definition of a neighbor? Connected at a vertex or
> along an edge? I suppose if we were to write such a filter the definition
> of a neighbor would be an optional parameter. I also suggest that this be a
> general filter so the same analysis could be applied to unstructured grids,
> etc. or to polygonal meshes with other than triangle cells.
>
> Best,
> W
>
> On Fri, Jul 22, 2016 at 6:51 AM, Lodron, Gerald <Gerald.Lodron at joanneum.at>
> wrote:
>
>
> Hi
>
> I have a mesh (vtkPolyData with all triangles) where i want to visualize
> the number of neighbouring cells/triangles for each cell/triangle. (I later
> may want to threshold/filter it with that number to remove “noisy”
> triangles on border with low number of neighbours)
>
> Is there a filter for that available?
>
> Best regards
>
>
> ------------------------------------------------------------------------------------
> Gerald Lodron
>
> Researcher of Machine Vision Applications Group
> DIGITAL - Institute for Information and Communication Technologies
>
> JOANNEUM RESEARCH Forschungsgesellschaft mbH
> Steyrergasse 17, 8010 Graz, AUSTRIA
>
> phone: +43-316-876-1751
> general fax: +43-316-876-1751
> web: http://www.joanneum.at/digital
> e-mail: gerald.lodron at joanneum.at
>
>
>
>
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> --
> William J. Schroeder, PhD
> Kitware, Inc. - Building the World's Technical Computing Software
> 28 Corporate Drive
> Clifton Park, NY 12065
> will.schroeder at kitware.com
> http://www.kitware.com
> (518) 881-4902
>
>
>
>
>
> --
>
> William J. Schroeder, PhD
> Kitware, Inc. - Building the World's Technical Computing Software
> 28 Corporate Drive
> Clifton Park, NY 12065
> will.schroeder at kitware.com
> http://www.kitware.com
> (518) 881-4902
>
--
William J. Schroeder, PhD
Kitware, Inc. - Building the World's Technical Computing Software
28 Corporate Drive
Clifton Park, NY 12065
will.schroeder at kitware.com
http://www.kitware.com
(518) 881-4902
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