[vtkusers] avoiding/removing non-manifold parts from the result of vtkMarchingCubes

[Bill Lorensen]

what level do you use?



On Fri, Aug 2, 2013 at 4:07 PM, Dr. Roman Grothausmann <
grothausmann.roman at mh-hannover.de> wrote:

> On 02/08/13 16:06, Bill Lorensen wrote:
>
>> Marching Cubes should not generate non-manifold surfaces. The offending
>> triangle
>> looks suspicious. What does the rest of your pipeline look like?
>>
>
> Thanks Bill for looking into this. I get the very same output using
> paraview and its contour filter when ticking "Generate Triangles" or using
> vmtkmarchingcubes (which seems to use only vtkMarchingCubes in
> vmtkmarchingcubes.py). To check it trice I used the simple program below
> and got the same output again. Only paraview and its contour filter without
> ticking "Generate Triangles" yields a different result.
>
> _____________________________
>
> #include <vtkSmartPointer.h>
> #include <vtkMetaImageReader.h>
> //#include <vtkImageConstantPad.h>
> #include <vtkMarchingCubes.h>
> #include <vtkXMLPolyDataWriter.h>//for vtp-files
>
> #include <vtkCallbackCommand.h>
> #include <vtkCommand.h>
>
>
> void ProgressFunction ( vtkObject* caller, long unsigned int eventId,
> void* clientData, void* callData )
>      {
>
>      vtkAlgorithm *d= static_cast<vtkAlgorithm*>(**caller);
>      fprintf(stderr, "\rFilter progress: %5.1f%%", 100.0 *
> d->GetProgress());
>      std::cerr.flush();
>
>      }
>
> int main(int argc, char* argv[]){
>      if( argc != 5 )
>         {
>         std::cerr << "Usage: " << argv[0];
>         std::cerr << " inputImage";
>         std::cerr << " outputMesh";
>         std::cerr << " level normals";
>         std::cerr << std::endl;
>         return EXIT_FAILURE;
>         }
>
>      if(!(strcasestr(argv[1],".mhd"**))) {
>         std::cout << "The input should end with .mhd" << std::endl;
>         return -1;
>         }
>
>      if(!(strcasestr(argv[2],".vtp"**))) {
>         std::cout << "The input should end with .vtp" << std::endl;
>         return -1;
>         }
>
>      vtkSmartPointer<**vtkCallbackCommand> progressCallback =
> vtkSmartPointer<**vtkCallbackCommand>::New();
>      progressCallback->SetCallback(**ProgressFunction);
>
>      vtkSmartPointer<**vtkMetaImageReader> reader =
>          vtkSmartPointer<**vtkMetaImageReader>::New();
>
>      reader->SetFileName(argv[1]);
>      reader->Update();
>
>      vtkSmartPointer<**vtkMarchingCubes> mc= vtkSmartPointer<**
> vtkMarchingCubes>::New();
>
>      mc->SetInputConnection(reader-**>GetOutputPort());
>      mc->SetValue(0, atof(argv[3]));
>      //mc->ComputeNormalsOn();
>      mc->SetComputeNormals(atoi(**argv[4]));
>      //mc->ComputeGradientsOn();
>      //mc->ComputeScalarsOn();
>      std::cout << "Executing discrete marching cubes..." << std::endl;
>      mc->AddObserver(vtkCommand::**ProgressEvent, progressCallback);
>      mc->Update();
>      std::cout  << std::endl << "done." << std::endl;
>
>      vtkSmartPointer<**vtkXMLPolyDataWriter> Pwriter = vtkSmartPointer<**
> vtkXMLPolyDataWriter>::New();
>      Pwriter->SetFileName(argv[2]);
>      Pwriter->SetInputConnection(**mc->GetOutputPort());
>
>      Pwriter->Update();
>
>      return EXIT_SUCCESS;
>      }
>
>
>
>>
>>
>> On Fri, Aug 2, 2013 at 8:23 AM, Dr. Roman Grothausmann
>> <grothausmann.roman at mh-**hannover.de <grothausmann.roman at mh-hannover.de><mailto:
>> grothausmann.roman at mh-**hannover.de <grothausmann.roman at mh-hannover.de>>>
>>
>> wrote:
>>
>>     Dear mailing list members,
>>
>>
>>     Recently, I came across a voxel-dataset that when meshed with
>>     vtkMarchingCubes results in a mesh that contains non-manifold edges
>> (magenta
>>     line in attached image).
>>     How can this be avoided?
>>     Using paraview's contour filter and switching off "Generate Triangles"
>>     creates a slightly different surface mesh that does not contain
>> non-manifold
>>     edges. However vtkMarchingCubes does not seem to have any option
>> concerning
>>     triangulation.
>>     What filter/option do I have to use to get the same result just with
>> pure VTK?
>>
>>     As a workaround: Is it possible to split the mesh at non-manifold
>> edges?
>>     vtkIntersectionPolyDataFilter sounds promising but seems to need
>> surfaces
>>     not just the edges.
>>
>>     Any help or hints are very much appreciated
>>     Roman
>>
>>
>>
>> --
>> Unpaid intern in BillsBasement at noware dot com
>>
>
> --
> Dr. Roman Grothausmann
>
> Tomographie und Digitale Bildverarbeitung
> Tomography and Digital Image Analysis
>
> Institut für Funktionelle und Angewandte Anatomie, OE 4120
> Medizinische Hochschule Hannover
> Carl-Neuberg-Str. 1
> D-30625 Hannover
>
> Tel. +49 511 532-9574
>
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-- 
Unpaid intern in BillsBasement at noware dot com
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