CGAL users discussion list

[Stephane Tayeb <>]

Lehtonen, Matti/HIIT wrote:
> Hi!
>
> When I am creating a mesh in Polyhedral mesh domain for later refinement, I 
> got
> following error always:
> terminate called after throwing an instance of 'CGAL::Assertion_exception'
>   what():  CGAL ERROR: assertion violation!
> File: /usr/include/CGAL/Mesh_3/Refine_facets_3.h
> Line: 526
> Explanation: Mesh_3 ERROR: A facet is not in conflict with its refinement 
> point!
> Debugging informations:
>   Facet: (0x25c9530, 2) = (-39.0758 -56.2995 12.8917 0, 130.77 133.294 16.7889
> 0, 10.7582 -6.93443 13.8584 0)
>   Dual: (-9.03193e+16 2.97869e+17 -1.05546e+19 0, 2.03556e+16 -6.71319e+16
> 2.37873e+18 0)
>   Refinement point: 115.949 138.899 17.0739 0
>
> What does it actually means and is there anything I could prevent from
> happening, like carefully selecting facet and cell criterias?
>
> thx,
> Matti Lehtonen
>
> Researcher, head programmer - Helsinki Institute for Information Technology 
> HIIT
> http://www.hiit.fi/

Hi,

This error means that the point which is inserted in the triangulation 
to refine a 'bad' facet does not destroy this facet.

Such an error often happen in those two cases:
 1- the dual is wrongly computed
 2- the intersection between the dual and the surface is wrongly computed

'1-' should not be a problem if you are using:
typedef CGAL::Mesh_triangulation_3<Mesh_domain>::type Tr;

'2-' depends on the Domain (oracle) your are using, and eventually on 
your input data.

It's hard to tell you about a 'generic' way to solve such an issue. 
Maybe it could be easier if you provide more informations about your 
oracle and data.

I hope it helps.
Regards,
Stéphane.

--
Stephane Tayeb
Software engineer - INRIA Sophia Antipolis
Geometrica Project-Team