CGAL users discussion list

[Stephane Tayeb <>]

Hi Ramin,

Let me just add that I get the same results as you on my computer. As 
Mariette says, it just mean that the mesh resolution is not sufficient 
to obtain a tetrahedralization of the volume between two very close 
input faces (they are seen as one single input face).

Something that you can probably do is to remove the faces which are 
incident to the same subdomain from the c3t3.

Best regards,
Stéphane.


Mariette Yvinec wrote:
> We add some discussions here about that.
> In fact, what happens in  the meshing  of polyhedral_domain
> is the following:
> - when you asked if a facet is on the surface, you actually
> test if there is any intersection between the dual segment of this facet
> and the input polyhedral surface
> - when you compare the sub_domain index of  the two cells incident
>  to a given facet, you  get the same index if the dual segment
> od the facets intersects twice (or any even number of time)
> the boundary surface of this subdomain.
>
> This explain while the first test can tell that a facet is on the surface
> while its two incident cells belong to the same subdomain.
> Such a behavior especially happens when the input polyhedral surfaces 
> has very close
> faces that the mesher has not  resolved in its actual  state of refinement.
> In particular, in the case in the model
> elephant.off, this may happens
> because the input triangulated surface of this model
> is self intersecting.
>
> I hope this helps,
> Mariette
>
> Ramin H wrote:
> > Recently most of my questions get ignored before a resolution is 
> > found. Are my questions irrelevant?
> >
> > On Wed, May 5, 2010 at 10:16 AM, Ramin H < 
> > <mailto:>> wrote:
> >
> >     I am attaching a slightly modified version of
> >     mesh_polyhedral_domain.cpp  and input.off (the elephant that comes
> >     with the CGAL examples).
> >
> >     Can you please compile and the .cpp file and run it against the
> >     input.off and see if you get any output such as:
> >     Cell and it's mirror have equal subdomain_index: 0
> >
> >     If yes, then why do you think this is happening? How can we fix this?
> >
> >     Thank you for your time.
> >     -Ramin

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