CGAL users discussion list

["Björn Zehner" <>]

Hello,
I hope I do not miss completely the point, but I think he wants the polygon that describes the outer (possibly concave) boundary of the alpha shape. Am I right Andi?
Kind regards,
Bjoern Zehner
 

----- Ursprüngliche Nachricht -----
Von: Mariette Yvinec <>
Datum: Freitag, 8. August 2008, 14:59
Betreff: Re: [cgal-discuss] Boundary of alphashapes
An:

> From what I see in wikipedia
> there is no relationship between alphashapes and shape file...

> and I still don't get what shape you want to get

> Andi Jochem wrote:

> Hello Mariette,  >   > a shapefile is a popular geospatial vector data format for geographic information systems  > (http://en.wikipedia.org/wiki/Shapefile)  >   > As you already know, I am not very familiar with alphashapes, but maybe you can help me.  >   >   >   > I am just looking for a method to get the shape, defined by a set of points (the "concave hull" , not the convex hull). After an intensiv google search, I found the CGAL library, installed it and tried to write a function using alpha_shapes_3.  >   > My question is: How can I get, the shape which is defined by a set of points in file?  >    >   > Thanks  >   > Andi  >   >   >   >   > -------- Original-Nachricht --------  >   

> Datum: Fri, 08 Aug 2008 14:37:54 +0200  > Von: Mariette Yvinec <>  > An:   > Betreff: Re: [cgal-discuss] Boundary of alphashapes  >     

>   >   

> I am rather familiar with Alpha_shape_3  > but I  can't answer your questions  > because I do not  understand them...  > In particular I don't know  > - what is a shapefile  > - nor which polygon you want to get out of alpha_shapes_3  > - nor what is  a roof plane  >   >  wrote:  >     

> Hello,  > I wrote a function to get the alphashapes of a set of points, but how  >       

> can I  >     

> transform this alphashapes in a polygon...???  > Is it posssible to transform the created alphashape in a shapefile???  >   > Is anybody familiar with alphashapes??   >   > Thanks a lot.  >   > andi  >     >       

> --   > Mariette Yvinec  > Geometrica project team  > INRIA  Sophia-Antipolis    >   >   >   > --   > You are currently subscribed to cgal-discuss.  > To unsubscribe or access the archives, go to  > https://lists-sop.inria.fr/wws/info/cgal-discuss  >     

>   >   

> --   > Mariette Yvinec  > Geometrica project team  > INRIA  Sophia-Antipolis    >   >   > 

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