I don't think that the geom union would in combination with the boundary would attach the island to the mainland. I don't think that there is a simple answer to my problem but I have attached a pic to help illustrate what I'm trying to accomplish.
Regards 2008/11/21 Lee Meilleur <[EMAIL PROTECTED]>: > > Howabout ST_BOUNDARY(ST_UNION(the_geom)) > > ________________________________________ > From: [EMAIL PROTECTED] [EMAIL PROTECTED] On Behalf Of Burgholzer,Robert > [EMAIL PROTECTED] > Sent: Friday, November 21, 2008 12:45 PM > To: PostGIS Users Discussion > Subject: RE: [postgis-users] return boundary > > So, > Do you need to iterate through the sub-polygons in your multi and get a > boundary of each? > > r.b. > > Robert W. Burgholzer > Surface Water Modeler > Office of Water Supply and Planning > Virginia Department of Environmental Quality > [EMAIL PROTECTED] > 804-698-4405 > Open Source Modeling Tools: > http://sourceforge.net/projects/npsource/ > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Travis Kirstine > Sent: Friday, November 21, 2008 10:51 AM > To: PostGIS Users Discussion > Subject: Re: [postgis-users] return boundary > > Thanks Obe > But I'm looking for something that returns the boundary of all the > selected features combined and attached. Something that has the > abilty to take the group the features together like convex hull but > keep the detail of the of the edge like boundary. > > 2008/11/21 Obe, Regina <[EMAIL PROTECTED]>: >> How about ST_Boundary? >> > http://postgis.refractions.net/documentation/manual-svn/ST_Boundary.html >> >> -----Original Message----- >> From: [EMAIL PROTECTED] >> [mailto:[EMAIL PROTECTED] On Behalf Of >> Travis Kirstine >> Sent: Friday, November 21, 2008 10:18 AM >> To: PostGIS Users Discussion >> Subject: [postgis-users] return boundary >> >> I have a multipolygon that has consists mainland and island polygons. >> I need to generate a single polygon / line that represent the boundary >> of the multipolygon as a whole, something like a convex hull but >> keeping the detail of the outer rings and joining the islands to the >> mainland. I have been try different combos of convex hull, buffer and >> difference but can't get what I'm looking for. >> >> Any thoughts would be greatly appreciated >> >> Regards >> >> -- >> Travis K. >> >> Toronto, Canada >> ------------------------------------------------------------ >> "She knows there's no success like failure >> And that failure's no success at all." >> -Bob Dylan- >> ------------------------------------------------------------ >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> ----------------------------------------- >> 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. >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > > > -- > Travis K. > > Toronto, Canada > ------------------------------------------------------------ > "She knows there's no success like failure > And that failure's no success at all." > -Bob Dylan- > ------------------------------------------------------------ > _______________________________________________ > 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 > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > -- Travis K. Toronto, Canada ------------------------------------------------------------ "She knows there's no success like failure And that failure's no success at all." -Bob Dylan- ------------------------------------------------------------
<<attachment: example.JPG>>
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