[postgis-users] Re: Feautures omitted from ST_Buffer operation
chris.hermansen at timberline.ca
Wed Mar 25 21:05:02 PDT 2009
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?
> On Wed, Mar 25, 2009 at 4:20 PM, Roger André <randre at gmail.com
> <mailto:randre at gmail.com>> 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
> 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,
> postgis-users mailing list
> postgis-users at postgis.refractions.net
Chris Hermansen mailto:chris.hermansen at timberline.ca
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
More information about the postgis-users