I resume (first as a repeat to myself) what I've learned from the various email on the topic
Vectors can be: LEVEL 1: - no topology -> very limited use LEVEL 2: - unclean topology -> limited use - clean topology -> full support I previously thought that LEVEL 2 was only possible for clean topologies, and I was wrong... At the moment there isn't a tool to list the the uncorrect geometries from a topological point of view. v.build only checks some constraints, not all. The proposal is to extend it to check against all the rules that are required to consider a geometry topologically correct (an extended flag to v defaul.build maybe). v.in.ogr builds and cleans (by default). It would be useful to have the "clean" phase available to be launched independently. I mean, something like an "automatic" flag for v.clean, that would operate the same cleaning as during the import of a vector. Conclusions: the topological correctness isn't a constraint for the vector topology data structure. GRASS haven't all the topology rules hard-coded (... or yes?). Most of thems (all?) are defined inside the code of v.build and v.clean, but I suppose that there isn't an autonomous library/functionality that provide the semantics of a "correct topology". Am I wrong? Thanks everyone for the support ;) giovanni
_______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
