Opened 3 years ago

Last modified 3 years ago

#5240 new defect

Mittelgebirge has an address that is too specific

Reported by: floscher Owned by: geocoding@…
Priority: minor Milestone:
Component: nominatim Version:
Keywords: Cc:

Description

The Black Forest is tagged with natural=highlands and highlands=mittelgebirge (see the relation on OSM.org).

See Wikipedia for a description, what a Mittelgebirge is.

If I reverse-geocode the coordinate 48.9660° N 8.4482° E with zoomlevel 14 or 15, I get the following:
Black Forest, Kurzbach, Hausach, Verwaltungsgemeinschaft Hausach, Ortenaukreis, Regierungsbezirk Freiburg, Baden-Württemberg, 77756, Germany, European Union
with Black Forest as neighbourhood.
Link to the query for zoomlevel 14

The problem with that is, that the Black Forest (160km x 60km) is not a neighbourhood. And it is not located in Kurzbach (an isolated dwelling in the center of the Black Forest), so my coordinate is more than 100km away from Kurzbach and definitely doesn't have the postal code of Kurzbach.

Probably Nominatim finds, that the coordinate is located inside the Black Forest relation (which is correct) and then takes the center of the Black Forest, which is Kurzbach, and derives the informations from suburb to continent of the center of Black Forest.

In my opinion two things should be changed:

  1. For every reverse-geocoded coordinate the postal code of the given coordinate (not of the center of the found OSM-object) should be returned. Example: The Black Forest contains many different postal codes (see my Overpass Turbo query for postal codes in the Black Forest), so if the OSM object of the Black Forest is returned, one of those many postal codes should be chosen, not always the one of Kurzbach.
  2. A Mittelgebirge (probably also other highlands) should not be counted as neighbourhood (in the hierarchy below suburb and city), because normally these are much larger than a city.

Thank you in advance,
floscher

Change History (1)

comment:1 Changed 3 years ago by lonvia

  • Summary changed from Mittelgebirge != neighbourhood to Mittelgebirge has an address that is too specific

The core problem with the reverse lookup was that natural features like mountain ranges shouldn't show up in addresses at all. This has been fixed in dd18e74/nominatim. Due to the way reverse lookup is implemented, this means that the Black Forest will not show up on reverse lookups at all.

As for the address of the Black Forest itself, that is indeed far too specific. I'm thinking to remove all parts of the address whose area is significantly smaller than the object itself. But that is a more complex change. Title adapted to reflect this second part.

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