Since you are going to PostGIS anyway cleaning in PostGIS is possible. Here is the 2.0 PostGIS doc, http://postgis.refractions.net/documentation/manual-svn/ST_MakeValid.html
I think that this PostGIS 2.0 function grows out of an old contrib. I've used the contrib with great success in the past. Here are a few links on that, http://linfiniti.com/2010/07/cleaning-geometries-inside-postgis/ http://trac.osgeo.org/postgis/wiki/UsersWikiCleanPolygons Eli >>> On 4/27/2011 at 7:55 AM, in message <[email protected]>, >>> Stephen Woodbridge <[email protected]> wrote: > On 4/27/2011 10:36 AM, Elijah Robison wrote: >> Hey devs, is anyone aware of an OGR approach to validate/clean >> geometries, for instance, as they are being converted from SHP to >> PostGRESql? >> It's not uncommon to have a handful of invalid geometries (usually >> self-intersecting polygons) in a parcel dataset, and it's impractical to >> correct them manually. In most situations I use the "Clean Geometries" >> function in ArcGIS, which does fix the problem. However this one >> functionality is my main reason to retain Arc in my primary tool chain. >> >> I've never found a scripting approach by trolling the search engines so >> I thought I'd ask here. > > This would be an interesting tool and you might want to check the > postgis list as I think there have been some tools posted there to clean > check tables in the database. > > Since I use the shp2pgsql data loader, my standard check and clean is: > > update mytable set the_geom=buffer(the_geom, 0.0) where not > isvalid(the_geom); > > -- at this point anything that is not valid probably need to be looked > -- at or needs something like a dump the polygon as line segments and > -- then st_build_area() on the line segments. > > select count(*) from mytable where not isvalid(the_geom); > select gid from mytable where not isvalid(the_geom); > > But this is all postgis related and not GEOS related, but you might be > able to do the same thing directly in GEOS if you know what strategies > work in postgis. > > -Steve W > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
