Also, ST_DWithin is a bounding box test, so its fast but not accurate. Youll want to do a second test with ST_Distance to get the actual distance after gathering up everything that results in true for ST_DWithin.
Best, Steve http://www.clemetparks.com/images/esig/cmp-ms-90x122.pngStephen Mather Geographic Information Systems (GIS) Manager (216) 635-3243 s...@clevelandmetroparks.com <http://www.clemetparks.com/> clevelandmetroparks.com From: postgis-users-boun...@postgis.refractions.net [mailto:postgis-users-boun...@postgis.refractions.net] On Behalf Of Pedro Costa Sent: Thursday, May 17, 2012 11:54 AM To: PostGIS Users Discussion Subject: Re: [postgis-users] break lines at intersections i found the error. the parallels are a less then 3 meters... thanks Em 17-05-2012 16:43, Pedro Costa escreveu: I'm already tried this function but with no good results, I do not understand why. You can see an example in the attached image. The streets are red lines. The parallel purple and what I want to clear yellow. Any idea ? I tried the st_dwithin like this: create table street8 as (SELECT paralell.geom FROM parallel,street WHERE st_dwithin(paralell.geom, streets.the_geom, 2.99 )) The 'line erros' that i want to delete are a less than 3 meters from streets... thanks Em 17-05-2012 16:32, Nicolas Ribot escreveu: Yes, it should be: st_dwithin will help you to find all lines from a table within a certain distance to other lines. Nicolas On 17 May 2012 17:23, Pedro Costa <pedrocostaa...@sapo.pt> wrote: Great Nicolos, works... It is possible select lines from one table a less than 3 meters from lines from another table?and delete them... thanks Em 17-05-2012 15:41, Nicolas Ribot escreveu: Hi Pedro, select (st_dump(st_union(geom))).geom from lines; will cut your network of lines at intersections. Nicolas On 17 May 2012 11:57, Pedro Costa <pedrocostaa...@sapo.pt> wrote: does anyone know how I can cut the lines at intersectionslike the image attached? I can´t install postgis 2.0 for now.... I see a few examples with st_union and st_dump but i don't understand... Thanks _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
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