[OSM-talk] Nominatim & US places

[Craig Wallace]

On 30/12/2010 20:33, Richard Welty wrote:

> Unclassified RoadBiittig Road, Sliters, Saratoga, 12018, ニューヨーク州,
> United States of America
> <http://www.openstreetmap.org/?minlon=-73.6051635742188&minlat=42.612548828125&maxlon=-73.5850830078125&maxlat=42.6175994873047>
>
> I'm not at all clear on why Saratoga is showing up at all. Saratoga
> County is a bit
> north and west of here; Biittig Road is in Rensselaer County (note that
> i did just
> fix some county border issues with Rensselaer County, it was mislabled
> Franklin County when it was imported, and the admin_level was missing
> from one segment. i need to go look at the eastern border with
> Massachusetts,
> i think that's wrong for Rensselaer County as well. i did these lookups
> before i
> made the corrections, and i don't know how rapidly changes like this impact
> Nominatim.)
>
> can someone involved in the Nominatim comment on this, and what needs to be
> done either on the map data side or the Nominatim side to get results that
> are more consistent with what an ordinary user-off-the-street might be
> expecting?

I'm not involved in Nominatim, but some comments anyway:
You can go to this page and search for a place: 
http://nominatim.openstreetmap.org/
In the results, click the little link for "Details", which will give 
more details of how Nominatim figured out the address. So for Biitig 
Road it gives this page: 
http://open.mapquestapi.com/nominatim/v1/details.php?place_id=14428803
As you can see from that page, it is using the place=county node for 
Saratoga. If counties etc are just mapped as nodes, then Nominatim has 
to guess which county a place is in, based on which node is nearest. And 
in this example, the node for Saratoga county is nearer to Biitig Road 
than the node for Rensselaer county.

So its much more useful to map counties as areas/multipolygon relations, 
and delete the place=county nodes. If you have now done this, and its a 
complete border, and tagged correctly, then Nominatim should use it for 
the address.
The same applies for cities/towns/villages etc - if they have defined 
boundaries, then its a good idea to map them instead of just a node.

Have you got a link for the way/relation for Rensselaer County? I could 
have a look at it, and see if its tagged correctly and complete.

Note that nominatim.openstreetmap.org page says its using data from 
2010/12/28, so newer changes won't show up yet.

Craig