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[Claudia Werner <>]

Thanks so far.
I already "played" with different alpha-values but couldn't find a sattifying result. I either get holes in the bunny or the ears are connected by other triangles. Especially this (wrong) triangles are the triangles I am wondering about. As far as I understood, a facet of the Delaunay-Triangulation is part of the alpha-shape iff its circumsphere is empty and has a radius smaler than alpha. But the radius of the circumsphere of the triangles between the ears of the bunny have a radius mush greater than alpha, so why aren't this triangles deleted? E.g. when using alpha-opt = 0,0013... there are still triangles with edge-length around 0,055 otherwise mush smaler triangles are "deleted"
Best,
Claudia




----- Ursprüngliche Mail -----
Von: "Daniel Duque" <>
An:
Gesendet: Dienstag, 26. November 2013 10:42:09 GMT +01:00 Amsterdam/Berlin/Bern/Rom/Stockholm/Wien
Betreff: Re: [cgal-discuss] Alpha_Shapes_3 Bunny

Hi,

I don't know much about the bunny, but if it's a nearly-regular mesh, with a well defined mean distance

between surface nodes, d, you should go for alpha values around, but larger than, d^2.

Best,

Daniel

On Tue, Nov 26, 2013 at 10:30 AM, Mariette Yvinec <> wrote:

Plain alpha_shapes is not a very good reconstruction method.
The "optimal" alpha-value is the smallest alpha value
that will give a single connected components including all data points.
It might not be the best one to see the Bunny feature appear.

You might try a few others alpha values,
just to be convinced things are working as they should.

Le 25/11/13 20:28, Claudia Werner a écrit :

Dear all,
I am working on Alpha_Shapes for triangulating a point cloud. As a first example I tried the example "Alpha_shapes_3/ex_alpha_shapes_3.cpp"
(http://doc.cgal.org/latest/Alpha_shapes_3/Alpha_shapes_3_2ex_alpha_shapes_3_8cpp-example.html) and wrote the result to an off-File as descirbed here:http://stackoverflow.com/questions/15905833/saving-cgal-alpha-shape-surface-mesh.
Displaying the result with MeshLab (using the off-file), I was wondering about the result (see attached picture).
Has anybody an idea why I don't get a better result? As in the example I used the optimal alpha.
I also attached the cpp-file.

Best Regards and thanks for your help,
Claudia

-- 
Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis