CGAL users discussion list

[Mariette Yvinec <>]

The regular triangulation computed always fills the convex hull
of it vertices,
but the mesher does not consider
all the tetrahedra as being part of the mesh :
only the tets with their dual (weighted) center point
within the cube are considered as part of the mesh
and listed by the C3T3.

Le 25/09/12 16:24, David Arken a écrit :

Thanks for all the help. Another followup question:

When I force the weights of a regular triangulation of a cube to be
all zeros, the output triangulation I get is not a decomposition of
the convex hull. Is this expected or a bug?

Thanks,
--Ram

On Tue, Sep 25, 2012 at 7:19 AM, Mariette Yvinec
<> wrote:

Le 24/09/12 19:10, David Arken a écrit :

Thanks for the quick reply Marriette. I did see the no exuder/perturb
requirement in the documentation, but missed the part that says the
other one. A few followup questions.

1. When I render the regular triangulation either in VTK or .mesh
format, I see pictures like this:

http://cgal-discuss.949826.n4.nabble.com/file/n4331141/Capture.jpg

I think there are others who have asked about this problem in the
forum before (as if it was an orientation problem).

One solution to avoid orientation problems
is to ask the
the viewer to render both sides of each facet.


2. After I call refine mesh, I can use:

typedef typename Tr::Finite_vertices_iterator Finite_vertices_iterator;
const Tr& tr_ = c3t3.triangulation();
for( Finite_vertices_iterator vit = tr_.finite_vertices_begin();
  vit != tr_.finite_vertices_end();         ++vit)
            cout << (*vit) << endl;

and I see 4d output. I am assuming the last number is a weight (most
of them are zeros). Now if I try to access the weight using

vit->weight()

I get a compilation error (vit->point() compiles and works). What am I
missing?


vit->point().weight() should work better


Thanks,
--Ram.






On Mon, Sep 24, 2012 at 12:56 PM, Mariette Yvinec
<> wrote:

The weights on the mesh vertices come from two sources
- the handling of one-dimensional features
- optimization through the exuder

If you don't want weights, you have
- to input no one-dimensional feature or use a Polyhedral_mesh_domain_
rather than a Polyhedral_mesh_domain_with_features_3
- and choose no_exude()
in the optimization options.



Le 24/09/12 15:02, David Arken a écrit :

I've 100k+ points, and the make_mesh+refine_mesh function puts weights
on a few hundred. I tried to give them no_perturb() and no_exude() --
but it seems it still puts weights on the points (is that a bug?). You
think computing the Delaunay from scratch is the right way to solve my
problem?

I was trying to go thru the list of points, find out the weighted
points, and was hoping to remove and reinsert them.  But the following
loop does not seem to compile: (Maybe my typedefs dont make sense?)

    // Fix regular triangulation
    typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
    typedef CGAL::Polyhedral_mesh_domain_with_features_3<K> Mesh_domain;
    typedef CGAL::Mesh_polyhedron_3<K>::Type Polyhedron;

    typedef CGAL::Mesh_triangulation_3<Mesh_domain>::type Tr;
    typedef
CGAL::Mesh_complex_3_in_triangulation_3<Tr,Mesh_domain::Corner_index,Mesh_domain::Curve_segment_index>
C3t3;
    typedef C3t3::Triangulation Tr;
    typedef typename Tr::Finite_vertices_iterator Finite_vertices_iterator;
    const Tr& tr_ = c3t3.triangulation();
    for( Finite_vertices_iterator vit = tr_.finite_vertices_begin();
         vit != tr_.finite_vertices_end();
         ++vit)
        std::cout << (*vit).weight() << std::endl;


Thanks.


On Mon, Sep 24, 2012 at 3:42 AM, Olivier Devillers
<> wrote:

Le 9/23/12 5:26 PM, David Arken a écrit :

What is the fastest way to convert a regular triangulation with
weights on points to another regular triangulation with all weights
zero. I hope that this will guarantee that the regular triangulation
is indeed a delaunay triangulation.

Thanks,

????

compute the Delaunay triangulation of the unweighted points !



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--
Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis



--
Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis

-- 
Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis