CGAL users discussion list

["Sebastien Loriot (GeometryFactory)" <>]

On 8/20/20 8:53 AM, Antoine Lavenant wrote:
> Thanks for answer me.
>
> I'm using the remove_almost_degenerate_faces() function.
>
> First of all, i needed to add a few times CGAL::to_double( ... ) in CGAL code 
> in order to compile my code. Maybe because i'm using an exact kernel ?
Indeed, I guess this non-documented function was not tested with an 
exact kernel. Feel free to open a PR to submit your patch.

> I'm moving the cap_threshold and collapse_length_threshold parameters. And 
> the number of almost degenerate triangles decreases. that's great ! Thanks 
> for that.
>
> When i move the needle_threshold from 1., the global shape of my polyhedron 
> changes too much. Is it normal ? For now, i will not use it.

the threshold is a bound on the largest angle in the triangle, expressed 
as a cosinus. If you lower too must the bounds, many triangles will be
detected as to be removed.

Best,

Sebastien.


> Thanks again,
> Antoine
>
> Antoine LAVENANT
> IGN / SD
> +33 1 43 98 80 00 - Poste : 76 69
> E-mail : 
>
> ________________________________________
> De :  [] de la part de 
> "Sebastien Loriot (GeometryFactory)" []
> Envoyé : mardi 18 août 2020 18:10
> À : 
> Objet : Re: [cgal-discuss] clean a polyhedron
>
> You can either directly isotropically remesh the modified region like in
> this example:
> https://doc.cgal.org/latest/Polygon_mesh_processing/#title21
>
> or you can use the non-documented function:
> remove_almost_degenerate_faces() defined in
> CGAL/Polygon_mesh_processing/repair_degeneracies.h
>
> also on the set of selected faces.
>
> The first option is better is you want to keep the shape of the
> intersection polyline but is not really atomic. The second option
> is atomic but it would require a first pass on the intersection edges
> if you want to preserve the intersection curve shape.
>
> Best,
>
> Sebastien.
>
>
> On 8/18/20 1:06 PM, Antoine Lavenant wrote:
> > Hi,
> >
> > After some boolean operations, a triangulated polyhedron may have small
> > triangles.
> >
> > I'd like to know if there is an easy way to clean it, by merging closed
> > vertex by exemple ?
> >
> > Thanks,
> > Antoine
> >
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