[postgis-users] Convert multipolygons to separate polygons

[Paragon Corporation]

As Mike mentioned below - ST_Dump is probably the fastest way to do this
(faster than ST_GeometryN if you need to dump all polygons out) and  then to
get Point on surface - would look something like this

SELECT sometable.field1, sometable.field2,
ST_PointOnSurface((ST_Dump(the_geom)).geom) As pos 
	 FROM somestatetable


Would dump out a point on surface for each polygon in each multipolygon as
separate records for each poly.

Hope that helps,
Regina
			   

-----Original Message-----
From: postgis-users-bounces at postgis.refractions.net
[mailto:postgis-users-bounces at postgis.refractions.net] On Behalf Of
Bresnahan, Mike
Sent: Tuesday, August 19, 2008 6:59 PM
To: PostGIS Users Discussion
Subject: RE: [postgis-users] Convert multipolygons to separate polygons

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Simon O'Malley said:
> Is there a way to split multipolygons into separate polygon features?
>
> Or is there a way to step through all the polygons in a multipolygon 
> and use pointonsurface to create a point for each polygon in the 
> multipolygon.

ST_Dump()
ST_NumGeometries()
ST_GeometryN()

Reference:
http://postgis.refractions.net/documentation/manual-1.3/ch06.html

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