[GRASSLIST:2726] Re: How to get topology of area edges

[Robert Stein]

Hi Radim,

    Thanks for the response...  however, I actually am quite interested in
the arc-node representations for their implicit representation of
neighboring cells...  So if someone could tell me how to reconstruct the
area polygons from the arc-node formated files that would be very helpful...
Thanks very much

Sincerely,

Rob

Robert Stein
Senior Technical Lead
Indiana Pervasive Technology Labs
rjstein at iu.edu   -   (317) 278-8154
----- Original Message -----
From: "Radim Blazek" <blazek at itc.it>
To: "Robert Stein" <rjstein at iu.edu>; <GRASSLIST at baylor.edu>
Sent: Tuesday, February 24, 2004 5:35 AM
Subject: [GRASSLIST:2721] Re: How to get topology of area edges


> On Monday 23 February 2004 22:10, Robert Stein wrote:
> > Hello,
> >
> >     I'm attempting to read GRASS's ascii vector output into a graphics
> > display program that I'm writing...  I produce this output (with
> > v.out.ascii) from a valid GRASS vector layer containing area polygons.
What
> > appears in the resulting data file is a line that denote an area and a
> > number of points followed by these points... i.e.
> >
> > A 4
> > easting northing
> > ...
> > easting northing
> > ...
> >
> > However... it appears that each area is not a closed ring as is stated
in
> > some of the documentation... but instead it appears to be an area-edge
> > representation which is stated in some other documentation :) This is
great
> > with me... and makes a good bit of sense... but I can't seem to find the
> > information that associates a particular edge with a polygon (i.e.
> > topology)
> >
> > Can someone point me in the right direction here? Is there some implicit
> > relationship that I'm missing or don't understand... Thanks in advance
for
> > your help
>
> Try v.out.ogr format=GML (5.7). You get closed polygons and it sounds
> much better if your application is based on GML :)
> Or better use OGR directly (with GML for example). There will be GRASS
support
> in OGR in future so it will be possible to switch to direct access.
>
> Radim
>
>
>