Generating a Polyhedron_3 from a triangle soup

[gy114]

Hi,

I generated a Polyhedron_3 from a triangle soup. I followed the examples and repaired the soup first. The triangles were already oriented. I then combined the soup to a Polyhedron_3, and then tried to repair the surface mesh as much as possible. I then illustrated both the faces (grey) and the borders (red) of the mesh (down below). It seems some halfedges are not merged or stitched. What should I do? Should I somehow increase the tolerance?

Please help. Thanks.

Here's the illustration:

Here's the code:

CGAL::Polygon_mesh_processing::repair_polygon_soup(points, triangles);
    // Then, since triangles are already oriented, we merge the soup to create the Polyhedron_3
    Polyhedron isoSurface;
    CGAL::Polygon_mesh_processing::polygon_soup_to_polygon_mesh(points, triangles, isoSurface);
    CGAL::Polygon_mesh_processing::merge_duplicated_vertices_in_boundary_cycles(isoSurface);
    CGAL::Polygon_mesh_processing::stitch_borders(isoSurface);
    CGAL::Polygon_mesh_processing::remove_degenerate_edges(isoSurface);
    CGAL::Polygon_mesh_processing::remove_almost_degenerate_faces(isoSurface);

[gy114]

This problem was fixed when I used a customized trait:

struct Array_traits {
        double marginSquared; // Member to store the squared margin for comparison

        // Constructor to initialize marginSquared
        Array_traits(double min_squared) : marginSquared(min_squared * 0.1) {} // Adjusting margin here directly

        struct Equal_3 {
            double marginSquared;
            Equal_3(double marginSquared) : marginSquared(marginSquared) {}

            bool operator()(const K::Point_3& p, const K::Point_3& q) const {
                return CGAL::squared_distance(p, q) < marginSquared;
            }
        };

        struct Less_xyz_3 {
            double marginSquared;
            Less_xyz_3(double marginSquared) : marginSquared(marginSquared) {}

            bool operator()(const K::Point_3& p, const K::Point_3& q) const {
                if (CGAL::squared_distance(p, q) < marginSquared) {
                    return false; // Consider equal within margin, so not less
                }
                // Lexicographical comparison considering margin
                if (std::fabs(p.x() - q.x()) >= marginSquared) {
                    return p.x() < q.x();
                }
                if (std::fabs(p.y() - q.y()) >= marginSquared) {
                    return p.y() < q.y();
                }
                return p.z() < q.z(); // No margin comparison needed for the last coordinate
            }
        };

        Equal_3 equal_3_object() const { return Equal_3(marginSquared); }
        Less_xyz_3 less_xyz_3_object() const { return Less_xyz_3(marginSquared); }
    };

and then :

CGAL::Polygon_mesh_processing::repair_polygon_soup(points, triangles, CGAL::parameters::geom_traits(Array_traits(min_square_length)));