On Fri, Nov 07, 2014 at 01:14:31PM -0800, Guillaume Drolet wrote: > I finally finished cleaning my topology, using a mix of SQL commands, > functions, and also using Sandro's QGIS topology editor plugin.
Congratulations! > In parallel, I also tried going the GRASS route, importing my original > shapefile in GRASS and applying the cleaning function (v.clean ...) as > suggested by Remi. I injected the result into PostGIS and created a > topology. Most of the 23 slivers were there in the topology so one of two > things: 1) GRASS didn't fix them (maybe I didn't choose an appropriate > tolerance) or 2) they were created by PostGIS when building the topology. I can't help here as I've never used GRASS for that yet. Would be interested in knowing more though. Maybe Remi can help there. > I'm gonna ask you one last thing if I may: I want to replace the original > geom column (i.e. that used to build the topogeom) with a topologically > correct one, and keep all the associated ecological attributes. Is this the > right way to do it: > > UPDATE syshiera.de_20k SET geom = topogeom::geometry; ? Yes, that gives you a topologically correct "snapshot" of current topology state (assuming you have no more unassigned or multiply-assigned faces). Note that there might still be cases in which the universal face enters between two faces creating small gaps. I guess a way to check that would be by computing angle between edges around each node and ensuring none is below a given threshold (just ideas for more development to improve coverage of useful functions ;) --strk; () Free GIS & Flash consultant/developer /\ http://strk.keybit.net/services.html _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
