[postgis-users] sum the values of overlapping polygons

Greg Allensworth gregor at greeninfo.org
Wed Jul 2 09:55:29 PDT 2014

You could take the union of them, which would merge the overlapping areas.

    (SELECT ST_UNION(geom) FROM table WHERE whatever=whatever)
) AS area;

Your resulting units would be the same as your projection, e.g. square 
degrees. So you may want to convert to an SRS that preserves area, e.g. 

    (SELECT ST_UNION(geom) FROM table WHERE whatever=whatever)
) AS area;


On 7/2/2014 9:47 AM, Alessandro De Martino wrote:
> Hi,
> I am looking for a way to sum the values of overlapping polygons.
> I have a polygon shapefile with thousands of records and I need to know
> how to sum the values of the polygons when they overlap.
> Thanks!
> _______________________________________________
> postgis-users mailing list
> postgis-users at lists.osgeo.org
> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users

Greg Allensworth, Senior Web GIS Developer
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