[GRASS-user] Re: Extract coordinates of vertices/nodes

[MS]

If a polygon has no other touching it, it should have 2 nodes and at  
least 2 verticies.

When polygons touch other polygons, topology comes into play.   So  
when polygon B is adjacent to, and touching polygon A, that makes a  
node because it is a shared line segment between polygon A and B.  The  
lines break with nodes when other features connect, to create  
topologically correct, non-overlapping polygons.

Mark

On Apr 30, 2010, at 8:15 AM, Sophie Leguedois <sophie.leguedois at ensaia.inpl-nancy.fr 
 > wrote:

>
> Thank you very much for your useful answers. The commands v.to.point  
> and
> v.out.ascii are doing the trick!
>
> About vertices and nodes, I noticed that you can have several nodes  
> for the
> boundary limit of a polygon. Why so? Is it beacuse the nature of the
> neighbour polygon is different?
>
> Regards,
>
> So.L.
>
> -----
> Sophie Leguédois
> Researcher - Inra (French National Institute for Agricultural  
> Research)
> Laboratoire Sols et Environnement (UMR 1120 LSE)
> Ensaia - 2 avenue de la Forêt de Haye
> BP 172 - 54505 Vandoeuvre-lès-Nancy - France
> Tel: +33 (0)3 83 59 57 62
> http://www.lse.inpl-nancy.fr/
> -- 
> View this message in context: http://osgeo-org.1803224.n2.nabble.com/Extract-coordinates-of-vertices-nodes-tp4973423p4985298.html
> Sent from the Grass - Users mailing list archive at Nabble.com.
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user