[postgis-users] Reference Grid

Paragon Corporation lr at pcorp.us
Sun Apr 19 20:58:38 PDT 2009

Does the below help any.  The below will give you the centroid of the
portion of geometries that intersect a reference grid where the grid of the
reference is defined by reference.the_geom
SELECT r.gid, r.the_geom,
ST_Centroid(ST_Collect(ST_Intersection(r.the_geom,p.the_geom))) As
FROM tblpolygons As p INNER JOIN reference As r ON ST_Intersects(p.the_geom,
GROUP BY r.gid, r.the_geom
Hope that helps,


From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of Bob
Sent: Sunday, April 19, 2009 1:58 PM
To: PostGIS Users Discussion
Subject: [postgis-users] Reference Grid

I'm using a reference grid of small polygons.
I have been trying to collect concurrent polygons into one geometry in order
to establish the centroid of the region covered. I've tried a number of
operations such as union, contains, accum etc.
I haven't been successful.
Can anyone give me some ideas??
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