Will st_boundary() help? Perhaps in conjunction with st_buildarea() and / or st_polygonize()?
You may Roger André wrote: > So I have a partial solution, but it creates another problem for me. > I'm able to properly buffer all of the features in Papua New Guinea by > doing an ST_Dump and blowing apart the multipolygon, then buffering > the individual polygons: > > SELECT name, ST_Buffer((ST_Dump(the_geom)).geom, .12) AS the_geom > FROM coastlines WHERE iso_3_code = 'PNG'; > > However, now I need to reassemble the polygons and dissolve the > internal boundaries. Is that possible? > > Roger > -- > > > On Wed, Mar 25, 2009 at 4:20 PM, Roger André <[email protected] > <mailto:[email protected]>> wrote: > > Hi All, > > I'm having some problems with features that are being returned > from an ST_Buffer operation in PostGIS. When I try to buffer the > extents of Papua New Guinea, a large region in the middle of its > extents is omitted. You can see a visual representation of this > at > > http://lagerratrobe.blogspot.com/2009/03/problem-with-postgis-stbuffer.html > > If I just select the country itself, I get back all of the > features that I'm expecting. In the image I've posted above, the > black area indicates the results of that query. > > I am using postgresql-8.3.5, and postgis-1.3.3. My select > statements is as follows: > select name, Buffer(the_geom, .12) from coastlines where > iso_3_code = 'PNG'; > > I've tried this using both a free countries shapefile, as well as > an ESRI one, and get the same results. I'm a bit baffled, and > unsure if I have a problem with both data sets, or in my query, > or...? If someone else has had a similar problem in the past, and > can shed some light on it, I'd greatly appreciate it. > > Thanks in advance, > > Roger > -- > > > ------------------------------------------------------------------------ > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > -- Regards, Chris Hermansen mailto:[email protected] tel+1.604.714.2878 · fax+1.604.733.0631 · mob+1.778.232.0644 Timberline Natural Resource Group · http://www.timberline.ca 401 · 958 West 8th Avenue · Vancouver BC · Canada · V5Z 1E5 _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
