The PostGIS wiki has some thoughts on overlays ... http://trac.osgeo.org/postgis/wiki/UsersWikiExamplesOverlayTables
Paul Ramsey wrote:
Union is trivial. Here's a query that generates a new set of polygons dissolved based on an attribute value: create table newtable as select st_union(the_geom), attribute group by attribute; Overlay is non-trivial, and I leave that to someone else to provide good SQL. The simple case of finding all the overlapping parts is easy, but filling in the non-overlapping parts is harder. P On Mon, Sep 21, 2009 at 3:32 PM, Ravi <[email protected]> wrote:Hi, am using other FOSS GIS GRASS and OpenJUMP for Polygon layers Union and Intersection (overlay) are there similar functions in postGIS THE LATEST RELEASE I have raised these issues some time before too. http://postgis.refractions.net/pipermail/postgis-users/2008-May/019515.html Ravi Kumar Keep up with people you care about with Yahoo! India Mail. Learn how. http://in.overview.mail.yahoo.com/connectmore _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users_______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
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