[postgis-users] GeomUnion and Intersection

[roxana at torre.nl]

Thanks!! that works and it's much easier..
roxana

> This should give you the simplified coastline:
> 
> SELECT AsGML(simplify(geomunion(the_geom), .05)) FROM worldmap;
> 
> --strk;
> 
> On Tue, Mar 01, 2005 at 02:56:32PM +0100, roxana at torre.nl wrote:
> > Hello,
> > I'm getting something further with my worldmap database. I have the esri
> > shapefile of Europe in it, now I'm trying to get data and visualize it.
> I'm
> > using the gml output, and that's going fine. 
> > The idea is to get all borders and coastlines, I want to have as less as
> > possible points. The queries I'm using are like this:
> > 
> > for the coastlines:
> > 
> > SELECT AsGML(simplify(GeomUnion((SELECT the_geom FROM worldmap WHERE
> cntry_name
> > ='France'),GeomUnion((SELECT the_geom FROM worldmap WHERE cntry_name
> > ='Netherlands'),(SELECT the_geom FROM worldmap WHERE cntry_name
> > ='Belgium'))),0.05));
> > 
> > and for each pair of countries:
> > 
> > SELECT AsGML(simplify(Intersection((SELECT the_geom FROM worldmap WHERE
> > cntry_name ='France'),(SELECT the_geom FROM worldmap WHERE cntry_name
> > ='Belgium')),0.05));
> > 
> > Is there another way to do this?. Specially for the first query: i saw you
> can
> > also use it with "geometry set" but I couldn't find what that is.
> > 
> > Thanks,
> > roxana
> > 
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