[OSM-dev] Topologicial correctness in OSM

Nick Black nickblack1 at gmail.com
Wed Jan 17 17:19:53 GMT 2007


Whilst trying to produce .osm from the brazillian TABs, I've run into
a problem, in that the output I can produce output in OSM XML, but it
is topologically incorrect, as it duplicates nodes at intersections.
My process is:

TAB > Import to PostGIS usign ogr2ogr > Script to talk to PG, and
input data to OSM MYSQL via dao.rb .

One solution to the problem is to go through mysql and compare each
lat and lon value to each other, identifying the duplicate nodes and
then deleting one set and correcting their parent segment - this seems
a rediculous way to do it though.

Does anyone have a better idea how to go about it?  I cant see how
PostGIS maintains topology, but it obviously does somehow.

Nick Black

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