Hi all,

I'm using Nominatim and overall it works great and gives mostly accurate results. But for some reason it consistently gives inaccurate results of reverse geocoding specifically for Dublin city center.

I created minimal reproduction environment of the issue:

https://nominatim-reverse-geocoding.stackblitz.io

When you click on the map it'll put a marker on the selected place and a second marker pointed on the result of it's geocoding. Most of the time it'll be couple of streets away or even further with wrong address name.

Oddly enough, when you get farther from the city center, the results become more accurate. First I thought it's the issue with lack of poi data across Ireland, but Galway or Cork, for example, do not suffer from this problem.

asked 21 Feb, 16:11

tim-k's gravatar image

tim-k
31113
accept rate: 0%

2

At least one of your problems is that you are including historic boundaries such as this one https://nominatim.openstreetmap.org/details.php?place_id=250604683

(21 Feb, 16:52) SK53 ♦

@SK53 what exactly does this mean and how not to include them when doing the request to Nominatim? Thanks.

(21 Feb, 17:04) tim-k

These are getting treated as current areas; they need to/should be filtered out before loading into Nominatim (e.g., using osmosis with tag-filter, osmfilter, osm2pgsql LUA scripts or the osm2pgsql style file). This might not be everything because the Irish OSM communities server returns better (but still not v. accurate) results https://nominatim.openstreetmap.ie/reverse.php?format=html&lat=53.34442437807821&lon=-6.2667801617031245&zoom=18.

(22 Feb, 12:42) SK53 ♦

Looks like an issue with the Nominatim software. As @SK53 said Nominatim seems to return historical boundaries (address rank 29) while those should be ignored in the search. https://nominatim.openstreetmap.org/reverse.php?format=html&lat=53.34442437807821&lon=-6.2667801617031245&zoom=18 Can you add that to https://github.com/openstreetmap/Nominatim/issues ?

permanent link

answered 21 Feb, 17:33

mtmail's gravatar image

mtmail
2.6k644
accept rate: 26%

Will do. Thanks.

(22 Feb, 10:14) tim-k

I've raised a new issue on the tracker https://github.com/openstreetmap/Nominatim/issues/1313

(22 Feb, 11:36) tim-k
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question asked: 21 Feb, 16:11

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last updated: 22 Feb, 12:42

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