Boundary of alphashapes

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Boundary of alphashapes

Andruit
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
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Re: Boundary of alphashapes

Mariette Yvinec-2
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

[hidden email] 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  



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Re: Boundary of alphashapes

Andruit
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 <[hidden email]>
> An: [hidden email]
> 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
>
> [hidden email] 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

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Re: Boundary of alphashapes

Mariette Yvinec-2
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 [hidden email]
An: [hidden email]
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

[hidden email] 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  



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-- 
Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis  


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Re: Boundary of alphashapes

"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 <[hidden email]>
Datum: Freitag, 8. August 2008, 14:59
Betreff: Re: [cgal-discuss] Boundary of alphashapes
An: [hidden email]


> 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 <A href="javascript:main.compose('new','t=Mariette.Yvinec@sophia.inria.fr')"><Mariette.Yvinec@...>  > An: <A href="javascript:main.compose('new','t=cgal-discuss@lists-sop.inria.fr')">cgal-discuss@...  > 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  >   > <A href="javascript:main.compose('new','t=andruit@gmx.de')">andruit@... 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    >   >   > 



-------------------------------------------------------------------------
Dr. Bjoern Zehner
UFZ Centre for Environmental Research Leipzig-Halle
Permoserstrasse 15
04318 Leipzig
Germany
http://www.ufz.de/index.php?en=5673
Tel: ++49 (341) 235 3979
Fax: ++49 (341) 235 3939

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Re: Boundary of alphashapes

Andruit
In reply to this post by Mariette Yvinec-2
Hello Mariette,
you are right, there is no relation between alphashapes and shapefiles.

The only thing I want to do, is to write the boundaries which are defined by the set of points into a file.

Or am I totally wrong and alphashapes are not the right method to solve my problem.

Thanks

andi


-------- Original-Nachricht --------
> Datum: Fri, 08 Aug 2008 14:59:14 +0200
> Von: Mariette Yvinec <[hidden email]>
> An: [hidden email]
> Betreff: Re: [cgal-discuss] Boundary of alphashapes

>  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 <[hidden email]>
> >> An: [hidden email]
> >> 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
> >>
> >> [hidden email] 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  
>
>
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to
> https://lists-sop.inria.fr/wws/info/cgal-discuss

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Re: Boundary of alphashapes

Andruit
In reply to this post by "Björn Zehner"
Thank you Bjoern,
you are right.

Andi

> -------- Original-Nachricht --------
> Datum: Fri, 08 Aug 2008 15:04:57 +0200
> Von: "Björn Zehner" <[hidden email]>
> An: [hidden email]
> Betreff: Re: [cgal-discuss] Boundary of alphashapes
>
> 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 <[hidden email]>
> Datum: Freitag, 8. August 2008, 14:59
> Betreff: Re: [cgal-discuss] Boundary of alphashapes
> An: [hidden email]
>
>
>
> > 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
> > > <[hidden email]>  > An:
> > > [hidden email]  > 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  >   >
> > > [hidden email] 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    >   >   >  
>
>
> -------------------------------------------------------------------------
> Dr. Bjoern Zehner
> UFZ Centre for Environmental Research Leipzig-Halle
> Permoserstrasse 15
> 04318 Leipzig
> Germany
> http://www.ufz.de/index.php?en=5673 
> Tel: ++49 (341) 235 3979
> Fax: ++49 (341) 235 3939
>

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Re: Boundary of alphashapes

Mariette Yvinec-2
In reply to this post by Andruit
Depending on the value you are going to choose for alpha,
you can get a whole family of different alphashapes
with different boundaries.

I am not sure that one of them corresponds to
what you are expecting

[hidden email] wrote:
Hello Mariette,
you are right, there is no relation between alphashapes and shapefiles.

The only thing I want to do, is to write the boundaries which are defined by the set of points into a file.

Or am I totally wrong and alphashapes are not the right method to solve my problem.

Thanks 

andi


-------- Original-Nachricht --------
  
Datum: Fri, 08 Aug 2008 14:59:14 +0200
Von: Mariette Yvinec [hidden email]
An: [hidden email]
Betreff: Re: [cgal-discuss] Boundary of alphashapes
    

  
 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 [hidden email]
An: [hidden email]
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

[hidden email] 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  



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-- 
Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis  



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Geometrica project team
INRIA  Sophia-Antipolis  


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Re: Boundary of alphashapes

Andruit
But how can I write the boundaries into a file. I would like to have look on the boundaries to be able to decide which is the best alpha for my set of points.

andi
-------- Original-Nachricht --------
> Datum: Fri, 08 Aug 2008 15:41:45 +0200
> Von: Mariette Yvinec <[hidden email]>
> An: [hidden email]
> Betreff: Re: [cgal-discuss] Boundary of alphashapes

> Depending on the value you are going to choose for alpha,
> you can get a whole family of different alphashapes
> with different boundaries.
>
> I am not sure that one of them corresponds to
> what you are expecting
>
> [hidden email] wrote:
> > Hello Mariette,
> > you are right, there is no relation between alphashapes and shapefiles.
> >
> > The only thing I want to do, is to write the boundaries which are
> defined by the set of points into a file.
> >
> > Or am I totally wrong and alphashapes are not the right method to solve
> my problem.
> >
> > Thanks
> >
> > andi
> >
> >
> > -------- Original-Nachricht --------
> >  
> >> Datum: Fri, 08 Aug 2008 14:59:14 +0200
> >> Von: Mariette Yvinec <[hidden email]>
> >> An: [hidden email]
> >> Betreff: Re: [cgal-discuss] Boundary of alphashapes
> >>    
> >
> >  
> >>  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 <[hidden email]>
> >>>> An: [hidden email]
> >>>> 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
> >>>>
> >>>> [hidden email] 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  
> >>
> >>
> >>
> >> --
> >> 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  
>
>
>
> --
> You are currently subscribed to cgal-discuss.
> To unsubscribe or access the archives, go to
> https://lists-sop.inria.fr/wws/info/cgal-discuss

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Re: Boundary of alphashapes

Mariette Yvinec-2
Alpha_shape_3 has an output operator to a Geomview_stream
that will let you see the boundary facets with Geomview.
If you don't have Geomview at hand you can  look at the code in
CGAL/IO/alpha_shape_geomview_ostream_3.h
and write similar code for another viewer.

Hope this helps.
Mariette

Andi Jochem wrote:
But how can I write the boundaries into a file. I would like to have look on the boundaries to be able to decide which is the best alpha for my set of points.

andi
-------- Original-Nachricht --------
  
Datum: Fri, 08 Aug 2008 15:41:45 +0200
Von: Mariette Yvinec [hidden email]
An: [hidden email]
Betreff: Re: [cgal-discuss] Boundary of alphashapes
    

  
Depending on the value you are going to choose for alpha,
you can get a whole family of different alphashapes
with different boundaries.

I am not sure that one of them corresponds to
what you are expecting

[hidden email] wrote:
    
Hello Mariette,
you are right, there is no relation between alphashapes and shapefiles.

The only thing I want to do, is to write the boundaries which are
      
defined by the set of points into a file.
    
Or am I totally wrong and alphashapes are not the right method to solve
      
my problem.
    
Thanks 

andi


-------- Original-Nachricht --------
  
      
Datum: Fri, 08 Aug 2008 14:59:14 +0200
Von: Mariette Yvinec [hidden email]
An: [hidden email]
Betreff: Re: [cgal-discuss] Boundary of alphashapes
    
        
  
      
 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 [hidden email]
An: [hidden email]
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

[hidden email] 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  



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Mariette Yvinec
Geometrica project team
INRIA  Sophia-Antipolis  



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Geometrica project team
INRIA  Sophia-Antipolis  



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Geometrica project team
INRIA  Sophia-Antipolis