Re: CGAL- Is there a method for manifold mesh?

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Re: CGAL- Is there a method for manifold mesh?

MaelRL
Hello,

I am not sure I fully understand what you want to do, but here are a
couple methods that are available in CGAL and can help you with non
manifold vertex / edges:

- Polygon_mesh_processing::is_non_manifold_vertex()
- Polygon_mesh_processing::non_manifold_vertices() --> to collect all
the nm vertices
- Polygon_mesh_processing::merge_duplicated_vertices_in_boundary_cycle()
--> create nm vertices when the same point appears multiple times on a
boundary
- Polygon_mesh_processing::duplicate_non_manifold_vertices() --> split
nm vertices into multiple distinct vertices so that the mesh is
combinatorially manifold
-
Polygon_mesh_processing::duplicate_incompatible_edges_in_polygon_soup()
--> upcoming, currently in PR https://github.com/CGAL/cgal/pull/4055

Hope this helps you.

Best,
Mael

On 18/02/2020 13:51, Frank Dz wrote:

> Hi~ I want to know is there a method for non-manifold mesh processing? I
> searched on Google, the most answers are about "checking whether a vertex of
> a polygon mesh is non-manifold" and so on.
>
> Thus is there a method for non-manifold mesh processing? For example, one
> may want to do navigation to iterate on the mesh. And do the double covering
> on the mesh to get a manifold mesh.
>
>
> Many thanks for any help!
>
> Best,
> Frank
>
>
>
> -----
> be open, be creative, be critical
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> Sent from: http://cgal-discuss.949826.n4.nabble.com/
>

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Re: CGAL- Is there a method for manifold mesh?

Frank Dz
Dear Mael,

I will try these methods! They are really helpful. Thanks!

Plus, the problem is that for a non-manifold structure. I want to make it a
2-manifold mesh.
The input is a non-manifold mesh:

<http://cgal-discuss.949826.n4.nabble.com/file/t376165/1.jpg>

And the output is a double covered 2-manifold mesh so that some geometric
processing algorithms for 2-manifold can be used.

I do not know if CGAL can handle this.


Best,
Zhiyang





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Re: CGAL- Is there a method for manifold mesh?

Frank Dz

Actually, to double covered mesh, it may not be necessary to actually change
the position of the points (such as moving along the normal line of the
face: I put an example here which moves the position of the points:
<http://cgal-discuss.949826.n4.nabble.com/file/t376165/2.jpg> ), but simply
to duplicate one or more such points.


Many thanks for your kind help and guidance.






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