[Insight-users] Normal overlap

[Niccolo' Camarlinghi]

Dear all,

I'm trying to evaluate normals to a surface.
I red an  mail about this topic 
http://www.itk.org/pipermail/insight-users/2008-June/026137.html , but i
was wondering if the extraction of the normals can be implemented using
simplex mesh that has a public method to compute normal at each node.
When i compute one  normal i got segfault in the last line of the
allegated code, someone can tell me if i'm doing a no sense operation?



Many thanks 

Niccolo' Camarlinghi 



  InputImageType::RegionType regione;
  InputImageType::SizeType size;
  InputImageType::IndexType index;
  size[0]=100;
  size[1]=100;
  size[2]=100;
  index[0]=0;
  index[1]=0;
  index[2]=0;
  regione.SetSize(size);
  regione.SetIndex(index);
  img->SetRegions(regione);
  img->Allocate();
  InputIteratorType it(img,regione);
  //create a sphere for extracting a surface
  for (it.GoToBegin();!it.IsAtEnd();++it)
    {

      InputImageType::IndexType point=it.GetIndex();

      if ((point[0]-50)*(point[0]-50)+
(point[1]-50)*(point[1]-50)+(point[2]-50)*(point[2]-50)>100)
	{

	  it.Set(0);

	}
      else
	it.Set(1);




    }

  

  typedef itk::DefaultDynamicMeshTraits< float, 3, 3, float, float,
float> MeshTraits;
  typedef itk::SimplexMesh<double,3,MeshTraits> SimplexMeshType;
  typedef itk::BinaryMask3DMeshSource< InputImageType, SimplexMeshType >
MeshSourceType; // this templated is defined with SimplexMeshType???



  MeshSourceType::Pointer meshSource = MeshSourceType::New();
  meshSource->SetInput(img);
  meshSource->Update();
  
  SimplexMeshType::Pointer simp;
  simp=meshSource->GetOutput();

  std::cout << "Number of cells"<< std::endl;
  std::cout<<simp->GetNumberOfCells()<<std::endl;
  std::cout << "Computer normal"<< std::endl;
  
  std::cout << simp->ComputeNormal(1) <<std::endl; // here i got the
segfault , the index in the method is the number of the chosen cell?