[vtkusers] vtkDelaunay2D from point cloud

[Schober Beatrix [STEMMER IMAGING GmbH]]

Hi all,

I am reading attached image (gray values as z) as point cloud which works fine only displaying the point cloud with 687.371 points (no Delaunay2D filter). As soon as I use the Delaunay2D filter, I get a stack overflow (from vtkFiltersCore.dll - vtkDelaunay2D::FindTriangle(...)).

On the other hand, when setting tolerance to 0.001, I get a mesh within 90 seconds. Actually I want to consider all points, or is it useful to set the tolerance?

Rendering an xyz file with 359.040 points takes 40 seconds (with tolerance = 0.001) with Delaunay2D filter, also too long in a user application.
Rendering an xyz file with 359.040 points takes 12 seconds (without setting tolerance) with Delaunay2D filter. (I do not understand this behaviour.)

Mainly I guess, I am doing something wrong in reading the point cloud and creating the vtkPolyData?


void addPoint(double x, double y, double z)
{
  vtkIdType id = m_vtkPoints->InsertNextPoint(x, y, z);
  m_vtkDepths->InsertNextValue(z);
  m_vtkCells->InsertNextCell(1);
  m_vtkCells->InsertCellPoint(id);
  m_vtkCells->Modified();
  m_vtkPoints->Modified();
  m_vtkDepths->Modified();
}


void createPolyData()

{

  m_vtkDepths->SetName("DepthArray");

  m_vtkPolyData->SetPoints(m_vtkPoints);

  m_vtkPolyData->SetVerts(m_vtkCells);

  m_vtkPolyData->GetPointData()->SetScalars(m_vtkDepths);

  m_vtkPolyData->GetPointData()->SetActiveScalars("DepthArray");



  if (m_vtkPolyData->GetNumberOfPoints() > 0)

  {

    // Set vertex (cell) normals

    vtkSmartPointer<vtkDoubleArray> normalsArray = vtkSmartPointer<vtkDoubleArray>::New();

    normalsArray->SetNumberOfComponents(3); //3d normals (ie x,y,z)

    normalsArray->SetNumberOfTuples(m_vtkPolyData->GetNumberOfPoints());



    //construct the normal vectors

    double cN1[3] = { 1.0, 0.0, 0.0 };

    double cN2[3] = { 0.0, 1.0, 0.0 };

    double cN3[3] = { 0.0, 0.0, 1.0 };



    //add the data to the normals array

    normalsArray->SetTuple(0, cN1);

    normalsArray->SetTuple(1, cN2);

    normalsArray->SetTuple(2, cN3);



    //add the normals to the cells in the polydata

    m_vtkPolyData->GetCellData()->SetNormals(normalsArray);

  }

}

I am really stuck as I was searching for descriptions, examples etc. since some days now. I hope you can give me as a newbie the right hint.

Thank you very much in advance!

Bea

Beatrix Schober
Image Acquisition Development

STEMMER IMAGING | Telefon: +49 89 80902-750
b.schober at stemmer-imaging.de<mailto:b.schober at stemmer-imaging.de> | www.stemmer-imaging.de<http://www.stemmer-imaging.de>

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