CGAL users discussion list

[Per Zetterlund <>]

As far as I understand, it can extract
a manifold Polyhedron as long as the the
surface embedded in the triangulation
actually is manifold. It does not in any
way enforce or aid in the process of making
the surface manifold, right?

When I try it I get lots of errors such as

CGAL::Polyhedron_incremental_builder_3<HDS>::
add_vertex_to_facet(): input error: disconnected facet complexes at vertex 
352:
           involved facets are: 1815 1814 1813 (closed cycle) and.
terminate called after throwing an instance of 'CGAL::Assertion_exception'
  what():  CGAL ERROR: assertion violation!
Expr: check_protocoll == 1
File: /usr/local/include/CGAL/Polyhedron_incremental_builder_3.h
Line: 225
Aborted (core dumped)

I guess that is because the embedded surface
was not manifold.

 /Per




On Tue, Dec 2, 2014 at 1:32 PM, Sebastien Loriot (GeometryFactory)
<>
 wrote:
> On 11/24/2014 09:10 AM, Per Zetterlund wrote:
>>
>> Hi all,
>>
>> This is an issue I've run into several times
>> in different applications. Say that I have a
>> Triangulation_3 and I do a binary labelling of
>> the cells. Then I want to extract the interface
>> surface between the labels as a manifold
>> Polyhedron_3. Often it happens that that the
>> topology of the actual triangle faces in the
>> triangulation is not manifold. Are there any
>> routines in CGAL to extract a manifold surface
>> from a triangulation that (in some sense) is
>> close to the true interface surface?
>
>
> There is nothing working out-of-the-box but looking
> at the file CGAL/IO/Complex_2_in_triangulation_3_polyhedron_builder.h
> should give you ideas of how a manifold surface mesh is extracted
> from a 3D triangulation.
>
> Sebastien.
>
>>
>> Any ideas?
>>
>>   /Per
>>
>
>
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