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Re: [cgal-discuss] Union of balls and self-intersecting mesh


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  • From: Sebastien Loriot <>
  • To:
  • Subject: Re: [cgal-discuss] Union of balls and self-intersecting mesh
  • Date: Wed, 24 Nov 2021 09:26:21 +0100
  • Authentication-results: mail2-smtp-roc.national.inria.fr; spf=None ; spf=Pass ; spf=None
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Thanks I could reproduce the issue.
So it turns out that this function does not use the mesher but a dedicated code.

As it is based on the dual of the Delaunay triangulation and that your
points are on a grid, I suspect that the dedicated code does not handle
correctly degenerate cases. To check that, I added some noise to the
input points and that removed the self-intersecting faces (mostly because of degenerate faces).

I opened the following issue to track the patching:
https://github.com/CGAL/cgal/issues/6147

Best,

Sebastien.

On 11/23/21 8:55 PM, Bruno Manganelli ( via cgal-discuss Mailing List) wrote:
Here is a somewhat minimal example.
Hope it's good enough!
Bruno


On Tue, Nov 23, 2021 at 5:55 PM Sebastien Loriot < <>> wrote:

It should not happen. IIRC, it is the output from the Surface_mesher
so it should be clean.
Would you have a minimal example showing the problem?

Best,

Sebastien.

On 11/23/21 6:44 PM, Bruno Manganelli (
<> via
cgal-discuss Mailing List) wrote:
> Hi,
>
> I am using the Union_of_balls_3 class and the mesh_union_of_balls_3
> function.
> However, in certain scenarios, the resulting mesh contains
> self-intersections (PMP::does_self_intersect(mesh) returns true).
> Is this expected?
> I can provide an example if required.
>
> Thanks!
> Bruno
>
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