Just for completeness sake, if your input geom is really ambiguous with the precision you choose, it may be faster in both human and machine time to use grass 7 to import and clean the topology, then export from grass 7 to postgis topology with the built-in grass function.
I ressort sometime to this trick because grass cleaning functionality are very advanced. Cheers, Rémi-C 2014-11-03 17:04 GMT+01:00 Guillaume Drolet <[email protected]>: > Sandro Santilli wrote > >> I suggest you take a look at edges having face 1831 on either > >> the right or left edge. Do any edge exist ? > > > > edge 5187 has face 1831 as its right face > > > >> The correct procedure to drop those slivers would be to assign > >> those small areas to the (closest|biggest|leftmost|youpickit) > >> TopoGeometry object, to one and only one, and then, if you really > >> need it, drop the edge internal to the TopoGeometry. > > > >> I made a QGIS plugin which may help you do some of these things > >> manually, which is useful in some cases, mainly to understand the > >> issues. > > > > The plugin you made is a great tool (thanks). I will first try to get the > > number of slivers down to > > a manageable number, which I had with setting the tolerance at 2.0 m, and > > then apply the > > TopoGeometry approach above. > > > >> So the error was right about there being another edge attached to the > >> node: > > > >> ERROR: SQL/MM Spatial exception - other edges connected (3912) > > > >> I'm guessing 3912 and 3908 are the two parallel edges in the picture > >> you attached: https://dl.dropboxusercontent.com/u/5196336/example1.bmp > > > > You're right, they are the two parallel edges. And it's the same for most > > of > > the some 650 slivers I have. > > > >> Again, QGIS may help you getting more info out of the visual, enable > >> the DBManager core plugin, select your topology schema and select > >> Schema->TopoViewer from the menu. > > > > I didn't know about the TopoViewer tool. I was importing the topology > > tables (node, edge, face) > > like any other PG geometry tables. Will explore with this new tool. > > > > > >> It's probably easier to clean up nodes for an areal topology than to > >> clean up faces. With my QGIS plugin (PostGIS Topology Editor) you can > >> select all nodes and click on a button which will drop all the ones > >> that are safe to drop. > > > > You're right! I'll create my topology again but with the 2.0 m tolerance, > > then run > > my function for getting rid of nodes that are not at intersections and > > finally, > > I will use the approach you suggested of working with the TopoGeometry > > objects and the > > relation table to eliminate the remaining slivers. > > > > Will keep you posted on how it goes. Again, I really appreciate your > help. > > Thanks. > > > > Guillaume. > > > > > > -- > View this message in context: > http://postgis.17.x6.nabble.com/Topology-cannot-delete-slivers-or-gaps-tp5007250p5007266.html > Sent from the PostGIS - User mailing list archive at Nabble.com. > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >
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