CGAL users discussion list

[Monique Teillaud <>]

Dear Max,

The 2D and 3D alpha shapes are working the same way. You can put a 
regular triangulation as template parameter of the alpha shape class, 
and get a weighted alpha shape. There, input points are weighted, and 
weights can actually be different.

Best regards,
        Monique

Eggersdorfer Maximilian wrote:
> Thank you for your quick reply, Andreas!
>
> I only used the 3d weighted alpha shapes before. There you could first create a triangulation and a weight for each point (weight = radius^2). With the triangulation I could create the alpha shapes. I am wondering if it is possible to do the same in 2d. I did not find this in the online manual for 2d alhpa shapes and in the example all weigths are the same. I tried to use the 3d code with a data set in 2d but it did not work. 
>
> Thanks again!
> max
>
>
>
> Max Eggersdorfer
> Particle Technology Laboratory, ETH Zürich
> Sonneggstrasse 3, ML F 18
> CH-8092 Zurich (Switzerland)
> +41 44 632 39 52
>
>
> ________________________________________
> From: Andreas Fabri 
> []
> Sent: Tuesday, January 04, 2011 8:59 PM
> To: 
>
> Subject: Re: [cgal-discuss] 2d weighted alpha shapes - various radii
>
> hi maximilian,
>
> the alpha has to do with the ball moving around.
> if all radii are the same you obtain something
> almost identical to just points.
>
> andreas
>
>
> On 04/01/2011 19:36, Eggersdorfer Maximilian wrote:
> > Hello Everybody,
> >
> > I try to use the 2d weighted alpha shapes to calculate the projected surface 
> > area of a union of balls. As far as I understand the alpha value is the same 
> > for all points (all circles have the same radius). Has anybody used 2d  
> > weighted alpha shapes already with various radii for different points?
> >
> > Thanks in advance!
> > Best
> > Max
> >
> >
> > Max Eggersdorfer
> > Particle Technology Laboratory, ETH Zürich
> > Sonneggstrasse 3, ML F 18
> > CH-8092 Zurich (Switzerland)
> > +41 44 632 39 52
> > <mailto:>
>
>
> --
> Andreas Fabri, PhD
> Chief Officer, GeometryFactory
> Editor, The CGAL Project
>
> phone: ++33.492.954.912    skype: andreas.fabri
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to
> https://lists-sop.inria.fr/wws/info/cgal-discuss


--
Monique Teillaud
INRIA Sophia Antipolis - Méditerranée
http://www.inria.fr/sophia/members/Monique.Teillaud/