CGAL users discussion list

[Andreas Fabri <>]

Hello,

What do you mean with "which is not found" ??

You find it, but the compiler does not?

Do the examples in examples/Surface_mesh_simplification compile
when unmodified?

andreas

On 21/06/2017 19:42, Ignacio Javier Osorio Wallace wrote:
> Thx a lot Laurent,
>
> So I'm reading about it. And in order to use the minimum length required
> as the stop predicate of the function. I need to:
>
> #include
> <CGAL/Surface_mesh_simplification/Policies/Edge_collapse/Edge_length_stop_predicate.h>
>
>
> which is not being found. I wonder if I need to link other flags to the
> compiler? (I already have CGAL, CGAL_CORE and CGAL_ImageIO, and boost
> stuff).
>
> I did follow the documentation:
> http://doc.cgal.org/latest/Surface_mesh_simplification/index.html
> found how to convert the c2t3 to a polyhedron:
> http://doc.cgal.org/Manual/3.6.1/include/CGAL/IO/output_surface_facets_to_polyhedron.h
>
> and I'm trying to make the algorithm work with the
> edge_length_stop_predicate using this example:
> https://github.com/CGAL/cgal/blob/master/Surface_mesh_simplification/examples/Surface_mesh_simplification/edge_collapse_all_short_edges.cpp
>
>
> I hope I'm on the right path.
> Thx a lot for the support,
> best regards,
> Ignacio.
>
> El 2017-06-09 05:20, Laurent Rineau (CGAL/GeometryFactory) escribió:
> > Le Thursday, June 8, 2017 8:59:46 PM CEST Ignacio Javier Osorio
> > Wallace a ?
> > crit :
> > > Hello CGAL community, I need a small help with a surface extraction that
> > > I need to implement.
> > >
> > > I'm creating a surface for a finite element algorithm. And I need the
> > > edges to have a minimum size restriction. I would be perfect if the SD
> > > of all the edges were as small as possible.
> >
> > Hi,
> >
> > You cannot define a minimal size for edges (or triangles) when using
> > `CGAL::make_surface_mesh`. If the size of edges is significantly
> > smaller than
> > the size criterion given to the critera object
> > (`CGAL::Surface_mesh_default_criteria_3`), then that probably means
> > that the
> > geometry of the domain surface has locally a small feature size.
> >
> > You may try post-process the result of `CGAL::make_surface_mesh` with a
> > surface simplification algorithm: export the `c2t3` object to a
> > polyhedron,
> > and then use the methods from the CGAL chapter "Triangulated Surface Mesh
> > Simplification":
> >
> >   http://doc.cgal.org/4.10/Surface_mesh_simplification/index.html
> >
> > But the global guaranties (no self-intersection) will no longer be
> > guaranteed.
> >
> > > Here is a the code.
> > > Thx for the help, btw.
> > > Best regards,
> > > Ignacio.
> > >
> > > typedef CGAL::Simple_cartesian<double> Kernel;
> > > typedef Kernel::Point_2 Point_2;
> > >
> > > // default triangulation for Surface_mesher
> > > typedef CGAL::Surface_mesh_default_triangulation_3 Tr;
> > > // c2t3
> > > typedef CGAL::Complex_2_in_triangulation_3<Tr> C2t3;
> > > typedef Tr::Geom_traits GT;
> > >
> > > typedef CGAL::Gray_level_image_3<GT::FT, GT::Point_3> Gray_level_image;
> > > typedef CGAL::Implicit_surface_3<GT, Gray_level_image> Surface_3;
> > >
> > > Tr tr;            // 3D-Delaunay triangulation
> > > C2t3 c2t3 (tr);   // 2D-complex in 3D-Delaunay triangulation
> > > char *inriaFile;
> > > char *outputFile;
> > >
> > > Gray_level_image image(inriaFile, 0.3);
> > >
> > > GT::Point_3 bounding_sphere_center(109,109,67);
> > >
> > > GT::FT bounding_sphere_squared_radius = float(218) * float(218) *
> > > float(2);
> > >
> > > GT::Sphere_3 bounding_sphere(bounding_sphere_center,
> > > bounding_sphere_squared_radius);
> > >
> > > Surface_3 surface(image, bounding_sphere, 0.00001);
> > >
> > > CGAL::Surface_mesh_default_criteria_3<Tr> criteria(30,2,2);
> > >
> > > CGAL::make_surface_mesh(c2t3, surface, criteria, CGAL::Manifold_tag());
> > >
> > > //for(C2t3::Vertex_iterator iter(c2t3.vertices_begin()); iter !=
> > > c2t3.vertices_end(); iter++ ) {
> > > //std::cout << iter->point().x() << iter->point().y() << iter->point()
> > > << std::endl;
> > > ////Point p(iter->point());
> > > //}
> > >
> > > std::ofstream out(outputFile);
> > > CGAL::output_surface_facets_to_off (out, c2t3);
> > > std::cout << c2t3.number_of_facets() << std::endl;
> > >
> > > std::cout << "qRx : Surface, final number of points: " <<
> > > tr.number_of_vertices() << "\n";
> > > std::cout << "qRx: Surface, end!!" << std::endl;
> >
> >
> >
> > --
> > Laurent Rineau, PhD
> > R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
> > Release Manager of the CGAL Project       http://www.cgal.org/

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

phone: +33.492.954.912    skype: andreas.fabri