# Boundary of alphashapes

10 messages
Open this post in threaded view
|

## Boundary of alphashapes

 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 -- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://lists-sop.inria.fr/wws/info/cgal-discuss
Open this post in threaded view
|

## Re: 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
Open this post in threaded view
|

## Re: Boundary of alphashapes

 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-- Psssst! Schon das coole Video vom GMX MultiMessenger gesehen? Der Eine für Alle: http://www.gmx.net/de/go/messenger03-- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://lists-sop.inria.fr/wws/info/cgal-discuss
Open this post in threaded view
|

## Re: 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 ```
Open this post in threaded view
|

## Re: 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 > An: 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 > > 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

Open this post in threaded view
|

## Re: Boundary of alphashapes

 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-- GMX startet ShortView.de. Hier findest Du Leute mit Deinen Interessen! Jetzt dabei sein: http://www.shortview.de/wasistshortview.php?mc=sv_ext_mf@gmx-- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://lists-sop.inria.fr/wws/info/cgal-discuss
Open this post in threaded view
|

## Re: Boundary of alphashapes

 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 > -- GMX Kostenlose Spiele: Einfach online spielen und Spaß haben mit Pastry Passion! http://games.entertainment.gmx.net/de/entertainment/games/free/puzzle/6169196-- You are currently subscribed to cgal-discuss. To unsubscribe or access the archives, go to https://lists-sop.inria.fr/wws/info/cgal-discuss
Open this post in threaded view
|

## Re: Boundary of alphashapes

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