[postgis-users] Union and Intersection of Polygon layers

[Paul Ramsey]

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 <ravivundavalli at yahoo.com> 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
> postgis-users at postgis.refractions.net
> http://postgis.refractions.net/mailman/listinfo/postgis-users
>