CGAL users discussion list

[Benjamin Kehlet <>]

2014-07-18 14:36 GMT+02:00 Laurent Rineau (CGAL/GeometryFactory)
<>:
> Le Friday 18 July 2014 13:07:01 Benjamin Kehlet a écrit :
>> Ah, I see. Thanks!
>>
>> I will try to come with an implementation of
>> Construct_initial_points() that makes sure all components are
>> represented.
>
> That will probably not be sufficient. If I remember well, when the domain 
> has
> sharp features, it is possible that initial points are inserted only on 
> sharp
> features. That might not be sufficient in you case, if you have a cube (with
> sharp features) containing a sphere (without sharp features).

Yes, I think that is the case here. I will try to see if I can come up
with something that guarantees that points from all components (if
that is the right term) are inserted.

>
>
>> Is the reason for shooting random rays that the points should be
>> spread out over the surface or could I just pick some points (eg. via
>> the vertex iterator)? (I generally find (bug) reproducability a nice
>> feature :) )
>
> You can pick points, but you should ensure that the points are not too close
> from each other, compared to the sizing criteria you specify. As the meshing
> algorithm only *insert* new points, if two initial points are closed, there
> will be a short edge between then, that will remain in the mesh.

I see. I suspected something like this. In fact, I have experienced
this in the 2D case where the input polygon contains short edges. I
can see why this is hard to do efficiently without the random
approach.

Thanks for your help!

Benjamin

>
> --
> Laurent Rineau, PhD
> R&D Engineer at GeometryFactory           http://www.geometryfactory.com/
> Release Manager of the CGAL Project       http://www.cgal.org/
>
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