Stephen >and see if you get a multipolygon ot a collection as the result.
A collection is the result of course. The mix of two geometry types is the one reason, but your idea leeds also to a collection because your idea tries to collect two multigeometries. I believe it is not possible to merge multipolygons into one multipolygon like MULTIPOLYGON(MULTIPOLYGON1, MULTIPOLYGON2,...). This geometry has to be a collection. Horst ------------------------------------------------ Dr. Horst Düster GIS-Koordinator, Stv. Amtschef Kanton Solothurn Bau- und Justizdepartement Amt für Geoinformation SO!GIS Koordination Rötistrasse 4 CH-4501 Solothurn Telefon ++41(0)32 627 25 32 Telefax ++41(0)32 627 22 14 mailto:[EMAIL PROTECTED] http://www.agi.so.ch -----Ursprüngliche Nachricht----- Von: Stephen Woodbridge [mailto:[EMAIL PROTECTED] Gesendet am: Mittwoch, 23. April 2008 17:59 An: PostGIS Users Discussion Betreff: Re: AW: RE: [postgis-users] Geometrycollection to Multipolygon I think you are getting the collection because you are mixing types. Try this (I haven't tried it): st_collect( st_collect(st_multi(polygon1), st_multi(polygon2)), st_multi(polygon3)) and see if you get a multipolygon ot a collection as the result. -Steve W Düster Horst wrote: > > Regina > > Thank you for your response. Mmmm.. your trick doesn't solve my problem. > Perhaps I should tell you why I do have a geometrycollection. My > startingpoint is a sequence of single polygons. My aim is to merge them > together to one multipolygon. I do this with st_collect. This works fine > with two polygons: > > st_collect(polygon1,polygon2) => multipolygon(1,2). > > When I Process the third polygon with: st_collect(multipolygon(1,2), > polygon3) => Geometrycollection(multipolygon(1,2),polygon3) > > I do get the geomtrycollection and so on. > > My main problem is to merge the three polygons into one multipolygon > with 3 geometries. > > When I solve this problem I can offer a procedure to clean invalid > geometries. > > Regards > Horst > > > ------------------------------------------------ > > Dr. Horst Düster > GIS-Koordinator, Stv. Amtschef > > Kanton Solothurn > Bau- und Justizdepartement > Amt für Geoinformation > SO!GIS Koordination > Rötistrasse 4 > CH-4501 Solothurn > > Telefon ++41(0)32 627 25 32 > Telefax ++41(0)32 627 22 14 > > mailto:[EMAIL PROTECTED] > http://www.agi.so.ch <http://www.agi.so.ch/> > > > > -----Ursprüngliche Nachricht----- > *Von:* Obe, Regina [mailto:[EMAIL PROTECTED] > *Gesendet am:* Mittwoch, 23. April 2008 14:24 > *An:* PostGIS Users Discussion > *Betreff:* RE: [postgis-users] Geometrycollection to Multipolygon > > This sometimes does the trick for me if they actually can be unioned > > ST_Union(GEOMCOLL, ST_GeomFromText('GEOMETRYCOLLECTION(EMPTY)', > yoursridhere) ) > > (your number 2 doesn't work because that is the aggregate form, not > because ST_Union can't handle geometry collections I think) > > > Hope that helps, > Regina > *From:* [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] *On Behalf Of > *Düster Horst > *Sent:* Wednesday, April 23, 2008 2:25 AM > *To:* postgis-users > *Subject:* [postgis-users] Geometrycollection to Multipolygon > > I do have a Geometrycollection which consists of a collection of > Multipolygons and Polygons. My aim is to create one single > Multipolygon from the mentioned Geometry collection. > > Until now I tried the following steps without result: > > 1. ST_BUFFER(GEOMCOLL,0.0) => It works but all inner rings of my > input geometry are lost. > 2. ST_UNION(GEOMCOLL) => doesn't work with Geometrycollections > > Does anyone has a solution to solve my problem? > > Best regards > Horst > > ------------------------------------------------ > > Dr. Horst Düster > GIS-Koordinator, Stv. Amtschef > > Kanton Solothurn > Bau- und Justizdepartement > Amt für Geoinformation > SO!GIS Koordination > Rötistrasse 4 > CH-4501 Solothurn > > Telefon ++41(0)32 627 25 32 > Telefax ++41(0)32 627 22 14 > > mailto:[EMAIL PROTECTED] > http://www.agi.so.ch > > > > *The substance of this message, including any attachments, may be > confidential, legally privileged and/or exempt from disclosure > pursuant to Massachusetts law. It is intended solely for the > addressee. If you received this in error, please contact the sender > and delete the material from any computer. * > > > > * Help make the earth a greener place. If at all possible resist > printing this email and join us in saving paper. * > > * * > > > ------------------------------------------------------------------------ > > _______________________________________________ > 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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