[vtkusers] Number of points in a KdTree?

[David Doria]

On Mon, Oct 26, 2009 at 4:53 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
> The purpose of  BuildLocatorFromPoints is described in the header. I
> suspect that if you use this method, you cannot get the information
> that you want.
>
> //     For the purpose of removing duplicate points quickly from large
> //     data sets, or for finding nearby points, we added another mode for
> //     building the locator.  BuildLocatorFromPoints will build a k-d tree
> //     from one or more vtkPoints objects.  This can be followed by
> //     BuildMapForDuplicatePoints which returns a mapping from the original
> //     ids to a subset of the ids that is unique within a supplied
> //     tolerance, or you can use FindPoint and FindClosestPoint to
> //     locate points in the original set that the tree was built from.
>
> On Mon, Oct 26, 2009 at 4:40 PM, David Doria <daviddoria+vtk at gmail.com> wrote:
>> On Mon, Oct 26, 2009 at 4:34 PM, Bill Lorensen <bill.lorensen at gmail.com> wrote:
>>> I think the problem is that there is not a dataset associated with the
>>> kdtree if you build it from points.
>>>
>>> If you build it from a dataset, there will probably be a dataset.
>>>
>>> Just a guess...


Trying to build the tree from a dataset:

	vtkSmartPointer<vtkPoints> Points = vtkSmartPointer<vtkPoints>::New();
  Points->InsertNextPoint(0.0, 0.0, 0.0);
  Points->InsertNextPoint(1.0, 0.0, 0.0);
  Points->InsertNextPoint(0.0, 1.0, 0.0);

	//get the number of points the file contains
	vtkIdType NumPoints = Points->GetNumberOfPoints();
  vtkstd::cout << "There are " << NumPoints << " points." << vtkstd::endl;
	
  vtkSmartPointer<vtkPolyData> Polydata = vtkSmartPointer<vtkPolyData>::New();
  Polydata->SetPoints(Points);

	//Create the tree
  vtkSmartPointer<vtkKdTree> KDTree = vtkSmartPointer<vtkKdTree>::New();
  KDTree->AddDataSet(Polydata);
	KDTree->BuildLocator();
	
  vtkstd::cout << "Number of points in tree: " <<
KDTree->GetDataSets()->GetNextDataSet()->GetNumberOfPoints() <<
vtkstd::endl;

I get an error "No cells to subdivide".  Does that mean I have to
create vertices for my points before calling BuildLocator()?

Thanks,

David