On Thu, Jul 01, 2010 at 09:43:33AM -0400, Stephen Woodbridge wrote: > 1. working with polygon coverages to maintain boundary coherence during > edits > 2. simplify adjacent polygons without leaving gaps between them. > 3. editing road networks and maintaining coherence of joined segments > and intersections > > While these are more high level application ideas and I guess at the > lowest level you could build a topology that would support any of these, > where did not seem to be support for any higher level functions that > would help support implementing these ideas.
Right, not very management function reach at this time... For (2) the simplification part it wouldn't be too hard to do. Currently, if you use ST_Simplify(TopoGeometry) you'd get an automatic cast from TopoGeometry to Geometry, and _then_ the Geometry would be simplified. A simple override of that function could instead _first_ simplify components and _finally_ polygonize them togheter to get you the Geometry. Would that meet your use case 2 ? For (3) I don't think topology is for you. SQL/MM defined another model which was "network". Networks have different characteristics from topology. For example you may have intersections which do not form nodes (think bridges). Case (1) is the whole point of keeping the representation of your data as a topology, but I'm not sure I understand what you mean by 'during edits'. Postgis topology does have a validation function you could run after edits, but I guess your edits would be on the app level. For instance QGIS itself does use some form of topological representation when doing edits. Would be interesting to see it cope directly with topology in the backend. --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
