CGAL users discussion list

[Dominik Szczerba <>]

As an independent check, I would suggest converting your models to GNU 
GTS format (easiest via STL format) and using its check routines. You 
can check GTS' boolean operations too to check it they work for your model.
-- Dominik

Laure Guicherd wrote:
> Hi everyone,
> First i would like to thank you for all the great work.
>
>
> I'm having a problem with boolean operations on Nef_polyhedron_3.
> I'm using a Simple_cartesian<Gmpq> kernel and so far everything was ok, 
> it really works fine with a lot of models :)
>
> But I'm in trouble with a model that seems to be problematic, that 
> passes every test with success (the Polyhedron converted from my 
> geometry is both "valid" and "closed", and the Nef polyhedron converted 
> from this polyhedron is "valid" and "simple".)
> So I can get a valid nef, but when i try to compute boolean operations 
> with a simple sphere (attached as sphere.off), the program crashes on :
>
> terminate called after throwing an instance of 'CGAL::Assertion_exception'
> what():  CGAL ERROR: assertion violation!
> Expr: itl != it->second.end()
> File: 
> /net/rnd/src/CGAL-3.4/linux-x86_64-gcc-4.1.1/include/CGAL/Nef_3/SNC_external_structure.h 
>
> Line: 1088
> Abort
>
>
> I must admit I am really stuck here, as the model seems closed, valid 
> and with no self-intersections.
> The strangest thing is that it works fine with a cube, or most of the 
> time if the sphere intersects the model differently.
>
> I'm really sorry that the model is really big, unfortunately I was 
> unable to reproduce the problem with a simpler one, so here is the path 
> to the .off file (that is too big to be attached for the mailing list) : 
> http://dl.free.fr/rXNVUQVqg
>
> Am i missing something ? Or do you think there is a problem with the 
> model topology ? And if there is, how can i detect it in the future to 
> prevent crashes ?
>
>
> Any help would be really appreciated, thank you !
> Best regards,
>
>
> Laure Guicherd