On Wed, Nov 02, 2011 at 10:26:08PM -0700, Elton Chan wrote: > Hi Sandro, > > I tried to run the two commands that you suggested. However, it returns some > empty layers only. (e.g. test.edge, test.face...). I check that there are > some warning message in the output pane.
Report the WARNING lines ? > I wonder if it is due to some geometry problem in the data set so that it > cannot generate the topology. Any kind of input should generate something, except the empty input. The only other reason I could think of would be an exception during processing. > Besides, I am thinking to use ST_SNAP to clear some gaps between polygons. I > have done some small test, it works. However, to apply the same for a layer > containing hundreds polygons, it requires to loop through all the possible > adjacent polygons respecting to each polygon. It will take a very very long > processing time. Any other idea? Any method to filtering those gaps first? I suggest you filter the gaps _after_ you create the topology. > Meanwhile, it seems ST_CreateTopoGeo is doing similar things as you describe > in the proposed toTopoGeometry. Correct me if I am wrong. It seems the > toTopoGeometry performance should be better than the ST command, right? While ST_CreateTopoGeo wants the _full_ input in memory, and wants to start with an _empty_ topology, the toTopoGeometry function would accept chunked input and _incrementally_ populate a topology. Moreover, the toTopoGeometry would _construct_ a TopoGeometry object representing the same space that was represented by the input geometry (only topologically). This would give you a value type which you can store in a table and thus associate with attributes. Such object would retain its shape while more components are added to the topology trough more calls to toTopoGeometry. --strk; () Free GIS & Flash consultant/developer /\ http://strk.keybit.net/services.html _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
