Hello, On my side, I often use st_buildarea(st_exteriorring((st_dump(geom)).geom)). And if I want to keep a single object for the original one, I union or collect them regarding their gid.
HTH Hugues. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom McCallum Sent: Monday, January 27, 2014 1:51 PM To: PostGIS Users Discussion Subject: Re: [postgis-users] Getting boundary of set of polygons St_MakePolygon does not take a multilinestring. ST_BuildArea looked possible, but it gives me back lots of little areas and not a single boundary for the whole set. It looks as though ST_Dump with ST_MakePolygon may be useful but am still trying to get the right form something like ST_MakePolygon( ST_DUMP( ST_BOUNDARY( ST_COLLECT( wkb_boundary ) ) .geom ) But it does not like the .geom bit. Any suggestions? On Mon, 27 Jan 2014 12:35:51 -0000, Nicolas Ribot <[email protected]> wrote: > Hi, > > You should try st_makePolygon, or st_buildArea depending on the result > you want (keeping holes or removing them). > > Nicolas > > > > On 27 January 2014 13:32, Tom McCallum <[email protected]> wrote: > >> Hello all, >> >> I am trying to get the boundary of a geometry(polygon) field in >> postgis (multiple polygons in this field). I have this so far: >> >> ST_BOUNDARY(ST_COLLECT(wkb_geometry)) >> >> which outputs MultilineString. I need to convert this to a polygon. >> I have tried all sorts of things from ST_DUMP to converting to text >> and then trying ST_BdPolyFromText but got nothing to work so far. >> ST_Convexhull gives me a polygon but unfortunately its not what I >> want. >> >> Could someone let me know what I should be calling. >> >> 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
