[OSM-dev] Determining if two linestrings are "similar"
ppawel at fastmail.fm
Fri Jan 4 12:49:44 GMT 2013
Here's an interesting problem I'm trying to tackle now in OWL...
You have two linestrings and the task is to determine if they are
"similar" or not. Similar means spatially "the same" as looked at by
human eye at zoom level 18 on a slippy map :-)
Note that the two geometries are not equal in ST_Equals sense. They
don't have to intersect but can intersect or even be almost the same
save for one node slightly moved.
OWL right now shows some changes that in fact are non-changes - e.g.
using simplify way feature of JOSM changes way nodes but preserves (or
only very slightly changes) way geometry. It is not a change worth
processing and showing to the user.
I tried ST_HausdorffDistance from PostGIS but for now it does not
yield useful results or maybe I am misinterpreting them.
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