I'm using GeoDjango (but I guess this is from the geos library). I have a set of polygons that compose a city surface and I want to merge them into a single one.
The code looks like this:
polygons = [zone.poly for zone in self.zone_set.all()]
poly = polygons[0]
for pol in polygons[1:]:
poly = poly.union(pol)
self.poly = poly
self.save()
The problem with this is I get a TopologyException after the first three mergings, stating there is a self-intersection
Shouldn't overlapping points be merged as a 'union'?