On Thu, May 15, 2008 at 5:20 AM, George Silva <[EMAIL PROTECTED]> wrote: > Hello all again, > > I´m curious. I´ve said in qgis list and some other 'desktop' GIS software > lists that the biggest feature missing for OSGIS is something like the > 'auto-complete' polygon in ArcGIS,, that would make life much easier.
Indeed! > I´ve been reading some things, and i´ve seem people mentioning trigger based > topology (eg cut out the overlaping area of digitized polygons, or,maintain > only the overlaping areas of the digitized polygons, and other related > issues). I think the hard part is deciding how you want to do this exactly, since all approaches involve changing the data somehow; a lot of people are chary of automatically deleting gaps, for example, lest they aren't really gaps (consider the Vatican Republic in a map of euro nations...). > I imagine that would be a trigger using something like after insert update > the_geom. > > Can you guys with more experience give me a example, so i can build my own? > Best pratices? Some light around this subject? Have you ever written a non-geo trigger in postgresql? If not, I would practice using the docs; I am pretty sure you could just modify NEW with a geo operator/ function. If so, I think a larger scale project needs to be embarked on. The work so far seems to me to be quite low level without a grand plan, and I think a grand plan is needed. I would start with a bunch of functions for modifying a geometry based on its neighbors and some topology constraints, then maybe a schema to store topology information, and only then start implementing triggers. But this is armchair quarterbacking--hopefully someone with some real experience will say something... _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
