What you say sounds very weird to me. I don't understand how postgis can consider a multipolygon as a polygon. Could you provide us a test sample of your data ?
Hugues. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom McCallum Sent: Tuesday, January 28, 2014 3:25 PM To: [email protected]; PostGIS Users Discussion Subject: Re: [postgis-users] Removing tiny polygons Yes I just want the largest polygons. The problem being that when I simplify the polygon it appears to need a lot more simplification due to these islands rather than if it just did did one mainland polygon ( asGeoJson comes in at 437 polygons rather than 1 polygon). Not sure why GeoJson can split it into multiple polygons but Dump[] just hands me one. Was hoping to use ST_Area but currently cannot break down the single polygon. Interestingly QGIS can, if I do single to multipart it can break down into main landmass and islands. What might be an equivalent postgis method for doing this? On Mon, 27 Jan 2014 19:15:18 -0000, Morten Sickel <[email protected]> wrote: > It depends on what you mean with "remove" - do you want to just have > the large polygons without the area that is covered by the small ones > or do you want to add the area of the small polygons onto one or more > of the larges? (e.g. how one typically wants to handle shiver > polygons) > > In the first case it is as easy as a query like > > select the_geom where ST_area(the_geom) > ... > > Morten > > > Tom McCallum skrev: >> Hi all, >> >> If I have a polygon geometry field which seems to be made up of a >> large number of tiny polygons and some larger ones, what is the best >> way to remove polygons below a certain size? Would I need to >> preprocess this and save in a new table/record or can I dynamically >> do it? >> >> Thanks >> >> Tom >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >> > > > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
