[OSM-dev] Nominatim and/or a fault-tolerant geocoder

Tom nominatim at tscholz.net
Mon Nov 28 23:03:35 UTC 2016


Hi everybody,

I’m in the quest for a geocoder for OSM that is fault-tolerant in regards of miss-spelled search terms.

The company I’m working for does different projects for customers in the logistics field. From every customer we receive several hundred thousand address-records, which we have to geocode in order to do different calculations. I started to use Nominatim for that (on an own installation), but it seems that Nominatim has not much of tolerance regarding miss-spelled street and city names. Especially on our last project in Russia it turned out, that street- and city-names often include abbreviations in different ways (like „street“, „str.“, „s“, …). Since we receive the address information from our customers, we have not much influence on the quality of the data. So there are not just these valid abbreviations, but also real spelling errors. Nevertheless we have to geocode as much of these addresses as possible. 

But right now, Nominatim throws out around 40% of the addresses, not finding anything, although the address is in OSM and could be found (just slightly different spelled). What I would expect is, that a geocoder gives me back some kind of answer for every question I ask, being it an exact match on the city or on the street, or only a „similar“ match. It should tell me if there was no 100%-match, there were several records found, matching my street or my city from e.g. 80% to 50%. So then I can decide later on which records I consider a match and which not. In any case the first row returned should be the best match available.

So I have a couple of questions here: 

Does anybody know of a geocoder for OSM-data that does this already? 
I found besides Nominatim there are several other geocoders. But I cannot test them all. Maybe some work already this way.

There is a Postgresql-module that seems to do just what I want: pg_trgm. It does not seem like Nominatim uses that right now.
Is there anybody already working on implementing this (or anything similar)?

If not, I would be willing to invest further time and effort into this, but I need some help on the internals of Nominatim, which I’m not firm with. 
Where would be the right place to integrate this into Nominatim? 
Does it make sense to try to put this into Nominatim?
Or would it be easier to use just osm2psql and build on top of that a new query-interface?


Thanks a lot for anybody who can help me getting forward with this issue!

Best regards,

Tom


PS: I put this on both mailing list, 'dev‘ and 'geocoding', since I’m not sure where it suits better. Please excuse me if this is wrong!
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