[Insight-users] [Insight users] itk::SimplexMeshToTriangleMeshFilter not exact ?

[Luis Ibanez]

Hi Benoit

Please read the Documentation:

http://www.itk.org/Insight/Doxygen/html/classitk_1_1SimplexMeshToTriangleMeshFilter.html


> This filter converts a 2-simplex mesh into a triangle mesh.
> 
> Convert a simplex mesh into a triangle mesh. Therefore the center of
> each simplex cell is computed. These centers are taken as the points
> for the triangle mesh then the points are connected.


So,
What you observe...
is what the filter is supposed to do...



I agree with you however in that sometimes it may be desirable
to move the points along the normals of the triangles. Otherwise
a convertion from Simplex-->Triangle, followed with Triangle-->Simplex
will not return the same Mesh.


The question is:


           "How much to shift along the normal ? "



If you feel audacious, you probably could make this improvement to
the filter, for this just look at the code in


           Insight/Code/BasicFilters/
               itkSimplexMeshToTriangleMeshFilter.txx


in the method Initialize(), in lines 49-55.  You will need the
correction to be made in the values in the containter "m_Centers".


Please let us know if you need help with the changes,



    Thanks,



       Luis




----------------
Benoit wrote:

> Hi all !
> 
> With the following lines, I don't get back the initial mesh :
> 
> 	typename ToSimplexFilterType::Pointer	simplexFilter	=
> ToSimplexFilterType::New();
> 	typename ToTriangleFilterType::Pointer	triangleFilter	=
> ToTriangleFilterType::New();
> 	
> 	// connect components
> 	simplexFilter->SetInput( pMesh );
> 	triangleFilter->SetInput( simplexFilter->GetOutput() );
> 
> The output of triangleFilter is inside the input mesh.
> It acts as if the vertices of the resulting mesh where considered as
> the centers of the simplex mesh's faces.
> I think there should be a correction along the vertices normal.
> 
> Regards,
> Ben
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