Same error. Tried both Polygon and Multipolygon. I'm not sure which the Tiger Data is.
On Tue, Jun 28, 2011 at 11:41 AM, Ben Madin <[email protected]>wrote: > Christian, > > My guess here is that because you've told the geometry to be a > MULTIPOLYGON, but you may have returned a POLYGON, you have indeed violated > the check constraint on the geometry type. > > try using st_multi() to get around it, as in : > > update public.tl_2010_us_cd111 set simple_geom = > ST_Multi(ST_SimplifyPreserveTopology(the_geom, 15)); > > > cheers > > Ben > > > > On 28/06/2011, at 11:23 PM, Christian Guirreri wrote: > > I get the following error: > ERROR: new row for relation "tl_2010_us_cd111" violates check constraint > "enforce_geotype_simple_geom" > SQL state: 23514 > > Here's my SQL: > select addGeometryColumn('public', 'tl_2010_us_cd111', 'simple_geom', 4326, > 'MULTIPOLYGON', 2); > update public.tl_2010_us_cd111 set simple_geom = > ST_SimplifyPreserveTopology(the_geom, 15); > > > On Mon, Jun 27, 2011 at 2:07 PM, Stephen Woodbridge < > [email protected]> wrote: > >> On 6/27/2011 1:37 PM, Christian Guirreri wrote: >> >>> I'm trying to do something fairly simple. I'd like to take the Tiger >>> 2010 Data - tl_2010_us_cd111 and tl_2010_us_county10 - and create shape >>> files that are considerably smaller and more simplified. In the past >>> I've just used MapShaper and been OK with that, but I was having trouble >>> uploading tl_2010_us_county10 into it and I've decided its time to learn >>> some GIS basics anyway. >>> >>> I've definitely successfully setup my environment - PostegreSQL 9 with >>> PostGIS. I've used the shp2pgsql wizard included with pgadmin to import >>> the data sets into their own databases, without the "Load Geography >>> column" checked. I've been able to export this data back to shp >>> using pgsql2shp and view the resulting shp in QuantumGIS and ACDSee >>> Canvas. >>> >>> But when it comes to simplification - I'm not sure where to even >>> start. I'm no database expert beyond some simple mysql so GIS is >>> especially overwhelming. I only know that I want to >>> use ST_SimplifyPreserveTopology() as I'm fairly certain a number of >>> things will disappear if I don't. >>> >>> Would love if someone could provide me with the SQL to make this happen! >>> >> >> First you should understand that ST_SimplifyPreserveTopology() works on a >> single geometry at a time and not on multiple geometries in a coverage. The >> difference is in a coverage the the polygons that share a common edge that >> is simplified would continue to have a common simplified edge. When polygons >> are simplified individually with knowledge of the adjacent polygons it is >> possible for gaps and overlaps to occur along the simplified edge. >> ST_SimplifyPreserveTopology() is designed to try and minimize these effects >> but there are no guarantees. >> >> You might try something like: >> >> select addGeometryColum('myschema', 'mytable', 'simple_geom', 4326, >> 'MULTIPOLYGON', 2); >> update myschema.mytable set simple_geom = >> ST_SimplifyPreserveTopology(**the_geom, >> <tolerance>); >> >> where <tolerance> is replaces by an appropriate value. This will depend on >> the some trial and error. The above assume srid=4326 which is probably not a >> good projection for doing simplification so you might want to project your >> data into some other UTM or Mercator projection depending on your coverage >> area and tolerance needs to be set with respect to those units. >> >> -Steve W >> ______________________________**_________________ >> postgis-users mailing list >> postgis-users@postgis.**refractions.net<[email protected]> >> http://postgis.refractions.**net/mailman/listinfo/postgis-**users<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 > >
_______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
