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Re: [cgal-discuss] Meshing implicit surfaces creates inside out meshes.


Chronological Thread 
  • From: "Sebastien Loriot (GeometryFactory)" <>
  • To:
  • Subject: Re: [cgal-discuss] Meshing implicit surfaces creates inside out meshes.
  • Date: Tue, 12 Jun 2018 18:09:37 +0200
  • Authentication-results: mail2-smtp-roc.national.inria.fr; spf=None ; spf=Pass ; spf=None
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try facets_in_complex_3_to_triangle_mesh()

https://doc.cgal.org/latest/Mesh_3/group__PkgMesh__3Functions.html#ga68ca38989087644fb6b893eb566be9ea

Sebastien.

On 06/12/2018 04:45 PM, Zesen Qian wrote:
Hi Sebastien,

Thank you for the comment. I actually encountered this problem as
well, and the method you suggested should solve it well. Only one
question remains, however: is there anyway to get a Surface_mesh from
c3t3 directly, besides calling export_surface_to_off() and then
reading it back?

Thank you.

Best,
Zesen

On Tue, Jun 12, 2018 at 6:44 AM, Sebastien Loriot (GeometryFactory)
<>
wrote:
We added some functions in PMP to handle this kind of issues.
See CGAL::Polygon_mesh_processing::orient()

https://doc.cgal.org/latest/Polygon_mesh_processing/group__PMP__orientation__grp.html#gafe035adcc4ff061b4438cc9dae591d00

Sebastien.

On 06/12/2018 11:31 AM, Raphael Grimm wrote:

Hi,
i am meshing implicit surfaces and sometimes the result is inside out (the
vertex order of triangles is wrong).

I attached three meshes and the code to show what i mean:
* 'sphere_r_const_1_1.000000.off' is correct
* 'sphere_r_const_2_1.000000.off' is inside out
* 'sphere_r_const_4096_1.000000.off' is correct

In both cases i meshed a unit sphere.
The only difference when creating the spheres is the squared radius i
passed to 'Sphere_3' when creating my 'CGAL::Implicit_mesh_domain_3'.
The first sphere got the exact squared radius '1' and the second the
larger value '2' and the third the value '4096'.
Hence i the issue can't be a too large bounding sphere.

Why does this happen and how can i prevent this?

Best regards,

Raphael


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