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<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">Dear all,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">I try to extract the boundary nodes of an unstructured grids. Based on the example <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">https://vtk.org/Wiki/VTK/Examples/Cxx/Meshes/BoundaryEdges<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">I used the following code:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">vtkSmartPointer<vtkUnstructuredGrid> grid = vtkSmartPointer<vtkUnstructuredGrid>::New();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">vtkSmartPointer<vtkDataSetSurfaceFilter> filter = vtkSmartPointer<vtkDataSetSurfaceFilter>::New();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">vtkSmartPointer<vtkFeatureEdges> edges = vtkSmartPointer<vtkFeatureEdges>::New();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">/* load mesh into grid */<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">...<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">/* extract the boundary points */<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">filter->SetInputData(grid);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">filter->Update();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->SetInputData(filter->GetOutput());<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->BoundaryEdgesOn();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->FeatureEdgesOff();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->NonManifoldEdgesOff();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->ManifoldEdgesOff();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->Update();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">vtkSmartPointer<vtkPolyData> polyData = edges->GetOutput();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">When I print out the number of the points in polydata (polydata->GetNumberOfPoints()) I obtain 0, i.e.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">polydata is empty. When I comment out the lines <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->NonManifoldEdgesOff();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">edges->ManifoldEdgesOff()<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">then I get some subset of points in polydata extrated from the grid but when I visualize these points I see that some boundary points are
missing and there are some inner nodes in polydata. Thus <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">polydata does not contain the exact set of the boundary points of the grid. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">Now I am not sure if this is the correct way to extract the boundary points from an unstructured grid<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">and I would like to ask if there is any. Thank you very much for your help!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">Kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE">Zoltan<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif;mso-fareast-language:DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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