CGAL users discussion list

[Adrien Lefieux <>]

Dear CGAL staff,

Lately, I have been looking a bit at the surface mesh skeleton system. 

I tried to get the correspondence between skeleton vertices to surface vertices correspondence, as displayed on the figure 66.2.c, which looks like what I expect: surface vertices are close to skeleton vertex as they are linked during the "shrinking" of the surface.

However, trying on the example simple_mcfskel_example.cpp, I obtain the following result (I could not reproduce the octopus, not having the mesh, so I took the teddy bear). This is not what I would be expecting as the correspondence appears to a bit everywhere on the upper part of the teddy.

Is this normal, to be expect or something is going wrong?

Using CGAL 4.11

This is just the CGAL::extract_mean_curvature_flow_skeleton(tmesh, skeleton) and then the correspondence is build for one skeleton vertice v and then the correspondence is accessed via: skeleton[v].vertices (just as in the example). This examples uses Polyhedron_3 with the simple cartesian kernel.

CGAL version 4.11 and 4.10 gave me similar results. However, with CGAL 4.9.1 the results look much better to me. Another way to see the issue is to load the correspondence-poly.cgal and, for version 4.10 and 4.11, the correspondence polylines are not all within the boundary of the domain. on the contrary, for 4.9.1 it seems to be (I can provide other images if you wish).

Using CGAL 4.9.1

I use Eigen 3.3 on an OS X machine with clang (Apple version 9) with release flags and boost 1.65.1 .

Thank you very much for the hard work,

Adrien Lefieux