[postgis-users] clip polygons

[Francois Hugues]

Hello, 

To complete these answers about the usage st_intersection in combination with st_intersects, if  you want to avoid to clip features "which simply intersect the border" you should try to add st_touches(a.geom, b.geom) = 'f' in the where clause.

Hugues 

 

--

 

Hugues FRANÇOIS

IR - UR DTM

 

Cemagref - IRSTEA Grenoble

2, rue de la papeterie

Domaine universitaire

38402 Saint-Martin-d'Hères CEDEX

 

04.76.76.27.44

06.77.66.21.31

 

hugues.francois at irstea.fr

 

________________________________

From: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-bounces at lists.osgeo.org] On Behalf Of Martin Davis
Sent: Tuesday, January 15, 2013 5:42 AM
To: postgis-users at lists.osgeo.org
Subject: Re: [postgis-users] clip polygons


Correct.  See http://postgis.net/docs/manual-2.0/ST_Intersection.html


On 1/14/2013 5:14 PM, Tim-Hinnerk Heuer wrote:


	I think Nicolas is more correct. St_Intersection sounds like a function that gets a geometry while St_Intersects returns a Boolean. 

	On Jan 15, 2013 6:24 AM, "Francisco Salas" <fsalas at pinar.geocuba.cu> wrote:
	

		Martha ,

		I think that you must use in the select sentence st_intersects(a.the_geom, b.the_geom) as the_geom , instead of a.the_geom

		 

		Francisco Salas
		
		

		 

		De: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-bounces at lists.osgeo.org] En nombre de Marta Debolini
		Enviado el: lunes, 14 de enero de 2013 12:01 p.m.
		Para: postgis-users at lists.osgeo.org
		Asunto: [postgis-users] clip polygons

		 

		Hi, 
		I am a new postgis user, so sorry if my request seems trivial for someone.
		
		I have to clip a polygon with another polygon file. I was used to do this operation with the simple comand "clip" in GRASS or QGIS. 
		How can I do the same operation in postgis? I tried with sy_intersect, but it takes also the polygons outside my area, which simply intersect the border.
		The request I wrote is:
		
		
		CREATE TABLE w_md.x
		AS (SELECT area, a.the_geom
		    FROM oc a, co b
		    WHERE st_intersects(a.the_geom, b.the_geom));
		    
		    ALTER TABLE w_md.x_1999 ADD column ggid1 serial;
		     ALTER TABLE w_mdi.x_1999 ADD PRIMARY KEY (ggID1);
		
		Thank you for your help,
		
		Marta


		_______________________________________________
		postgis-users mailing list
		postgis-users at lists.osgeo.org
		http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
		
		


	 
	
	_______________________________________________
	postgis-users mailing list
	postgis-users at lists.osgeo.org
	http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
	

	 
	

	No virus found in this message.
	Checked by AVG - www.avg.com
	Version: 2013.0.2805 / Virus Database: 2637/6000 - Release Date: 12/31/12
	Internal Virus Database is out of date.