<br><br><div class="gmail_quote">2010/1/15 Hamish <span dir="ltr"><<a href="mailto:hamish_b@yahoo.com">hamish_b@yahoo.com</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div class="im">Will wrote:<br>
> Thanks - but what I really want is a list of unique nodes<br>
> (i.e. where three boundaries meet, there would be one node,<br>
> with an id) and assign this id to the relevant boundaries.<br>
> Perhaps that isn't possible. It might be easier to do<br>
> this in PostGIS. I need to be able to run recursive<br>
> queries in PostGIS to pick up connected boundaries.<br>
<br>
</div>Hi,<br>
<br>
have a look at 'v.build option=dump,sdump,cdump'.<br>
<br>
there you can export the topology to stdout, etc.<br>
<br>
<br>
it would be nice if you could write up your findings/method<br>
into a small wiki page when you are done, there is a real lack<br>
of PostGIS+GRASS documentation.<br>
<font color="#888888"><br>
<br>
Hamish<br>
<br></font></blockquote><div>Hi Hamish<br><br>Where should I write such a wiki page do you think? To be honest I'm not sure I'm using best practices - I needed a quick fix for a one-off job - I've been using shapefiles as an interchange medium. <br>
</div></div><br>I just rolled my own start/endpoint thing - it was pretty simple in Postgis to run<br>/* get table of unique start/endpoints */<br>insert into node (geom)<br>select st_startpoint(geom) from bound<br>union<br>
select st_endpoint(geom) from bound<br><br>then<br>/* assign node ids to bounds */<br>update bound set startnode_id = (select id from node where node.geom = st_startnode(bound.geom))<br><br>Cheers<br><br>Will<br>