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[Andreas Fabri <>]

Hello,

I've rewritten the program you posted and I've put it on github:
https://gist.github.com/afabri/32a7b4082208bd53b78d

I did not really try to understand your program,
so let me just make some remarks:

Note that when you have a cavity the infinite vertex is
not a vertex of a cell.

Also never create or copy a Cell, only use Cell_handle
or Cell_iterator and access data with ->

You cannot fully control the number of inner vertices,
as the mesh generator will in any case Delaunay tetrahedra.

There are less vertices if you do not set the
cell_radius_edge_ratio

Best,

Andreas

On 26/01/2016 14:36, Pierre Hallot wrote:
> Hello,
>
> I have a few questions on the mesh_optimization_lloyd_example that can
> be found in cgal/Mesh_3/examples/Mesh_3/mesh_optimization_lloyd_example.
> I am currently using the provided example (liver.inr.gz) and just trying
> to interact with the results.
>
> First, I am trying to find the points that are inside the created mesh,
> and to differentiate them from those that are on the boundary.
>  From what I've read, I can find them based on the fact that a vertex on
> the boundary will have one adjacent vertex which is infinite.
> I thus made the following code that I added at the end of the file
> without modifying anything else:
>
> Tr t = c3t3.triangulation();
>
> // sets so that the same points are not added twice
> std::set<C3t3::Vertex_handle> innerVertices;
> std::set<C3t3::Vertex_handle> outerVertices;
>
> for (C3t3::Cells_in_complex_iterator cell =
> c3t3.cells_in_complex_begin(), end = c3t3.cells_in_complex_end(); cell
> != end; ++cell)
> {
>      const Tr::Cell c(*cell);
>
>      // each tetrahedra has 4 vertices
>      for (int i = 0; i < 4; ++i)
>      {
>           // the vertices connected to the one we are checking
>           std::vector<C3t3::Vertex_handle> adjacent_vertices;
>           t.adjacent_vertices(c.vertex(i),
> std::back_inserter(adjacent_vertices));
>           bool onBoundary = false;
>           int counter = 0;
>           for (std::vector<C3t3::Vertex_handle>::iterator it =
> adjacent_vertices.begin(); it != adjacent_vertices.end(); ++it)
>           {
>               if (t.is_infinite(adjacent_vertices.at(counter)))
>              {
>                   onBoundary = true;
>                   break;
>              }
>               ++counter;
>           }
>
>           if (!onBoundary)
>           {
>               innerVertices.insert(c.vertex(i));
>           }
>           else
>           {
>              outerVertices.insert(c.vertex(i));
>           }
>      }
> }
>
> std::cout << "CountInner: " << innerVertices.size() << std::endl;
> std::cout << "CountOuter: " << outerVertices.size() << std::endl;
>
> However, no vertex seems to be infinite and thus every point is
> considered as inside the complex. How is it possible?
>
>
> Related to this, the File_medit.h outputs a dimension in the .mesh file
> (the fourth parameter).
> I think I read somewhere that 3 means it is inside the complex while 2
> is on the boundary.
> That's exactly what I need, however for the liver, there are about 2000
> vertices (out of a total of 3361) with dimension 3 and less than a
> thousand with dimension 2, the rest has a dimension of 1, 0 or -1.
> I would have expected to have much more vertices on the boundary than
> inside the complex however, is what I am saying correct?
> Moreover, if I replace the liver.inr.gz file by my own .inr file,
> everything has a dimension of 1, which makes this method useless.
>
>
> Lastly, is it possible to fix the number of vertices inside the complex
> that will be created during the make_mesh_3 call? For instance, I would
> like to have only 256 vertices inside. (I don't care about the number on
> the boundary.)
>
> Kind regards,
> Pierre Hallot

--
Andreas Fabri, PhD
Chief Officer, GeometryFactory
Editor, The CGAL Project

phone: +33.492.954.912    skype: andreas.fabri