[vtkusers] method to remove points in a polydata

[David Doria]

On Thu, Jun 23, 2011 at 9:13 AM, nuno.jf <nunofernandes7 at gmail.com> wrote:
> Hi David, thank you for your help.
> I used the example you had shown me, and changed it to read a polydata and
> use it as input the methods described:
>
>  //Read a polydata
>        vtkPolyDataReader * imp = vtkPolyDataReader::New();
>        imp -> SetFileName(argv[1]);
>        imp -> Update();
>
>    //Create the tree
>  vtkSmartPointer<vtkKdTreePointLocator> pointTree =
>      vtkSmartPointer<vtkKdTreePointLocator>::New();
>  pointTree->SetDataSet(imp->GetOutput());
>  pointTree->BuildLocator();
>
>  // Find the k closest points to (0,0,0)
>   int k = 1;
>  double testPoint[3] = {0.0, 0.0, 0.0};
>  vtkSmartPointer<vtkIdList> result =
>      vtkSmartPointer<vtkIdList>::New();
>
>  pointTree->FindPointsWithinRadius(5.0, testPoint, result);
>
>  for(vtkIdType i = 0; i < k; i++)
>    {
>    vtkIdType point_ind = result->GetId(i);
>    double p[3];
>    imp->GetOutput()->GetPoint(point_ind, p);
>    std::cout << "Closest point " << i << ": Point "
>        << point_ind << ": (" << p[0] << ", " << p[1] << ", " << p[2] << ")"
> << std::endl;
>    }
>
> The problem is that the application stops responding and I got nothing in
> the output. Could you please help me to see what is wrong? What I need to do
> is to create a new polydata and set the resulting points as its input
> points.

I suggest you use synthetic data as the input so we can more easily
help you debug. That is, use a vtkPointSource or something instead of
a vtkPolyDataReader with an actual file. Also, is there a reason
you're using vtkPolyDataReader instead of vtkXMLPolyDataReader?

To create the output polydata from points, you would create a
vtkPoints, use InsertNextPoint, and then add it to a polydata with
SetPoints. You can see this done here:

http://www.itk.org/Wiki/VTK/Examples/Cxx/IO/ReadPlainText

David