CGAL fails to detect some non-manifold vertices

[stla]

Hello,

According to the R package Rvcg, the mesh in the attached off file has two non-manifold vertices. However CGAL does not find them. I proceed as follows:

    std::vector<halfedge_descriptor> hds;
    std::back_insert_iterator<std::vector<halfedge_descriptor>> bii = std::back_inserter(hds);
    PMP::non_manifold_vertices(mymesh, bii);
    Rcpp::Rcout << "NMV: " << hds.size() << "\n";

Is it correct?

The computation of the normals crashes the session, but I think it would work if these two vertices were removed (because this is the behavior in R).

clippedmesh.off.txt

[stla]

Moreover CGAL::is_closed() claims that this mesh is closed:

[afabri]

When I load the off file in the Polyhedron demo of CGAL I get the warning that there are 472 isolated vertices and that non-manifold vertices have been found. Can you please put a self contained cpp on gist.github.com instead of a 4 lines of code in a text.
And the stistics are:

[stla]

Ah ok, maybe writing the mesh to a file and then reading it solves the issue.

In fact I had an original mesh that I copied and I removed some faces of the copy. That's how I obtained this mesh. Running PMP::remove_isolated_vertices(mesh) did not remove anything.

I changed my strategy: now I use

PMP::orient_polygon_soup(points, polygons, CGAL::parameters::visitor(soupvis))

where points are all the vertices of the original mesh, polygons are the faces I want to keep, and the visitor is here to print a message if non-manifold vertices are found. This works fine. Then I use PMP::polygon_soup_to_polygon_mesh.