[OSM-talk] Nominatim data and code updates

colliar colliar4ever at aol.com
Sun Aug 26 15:38:17 BST 2012


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On 26/08/12 15:49, Brian Quinion wrote:
> tl;dr: nominatim is updated (data and code), add wikipedia tags and 
> label/admin_centre relation member to improve search quality.
> 
> As some of you may have noticed Sarah (lonvia) has been busy updating the
> openstreetmap nominatim instance.  It should now be fully up to date and
> back running live updates, so, if anyone is still finding data that they
> have added is not included please let us know by email on the geocoding
> mailing list, via trac (select nominatim component) or on either the #osm
> or #osm-nominatim irc channels.
> 
> In the process of updating the data we also took the opportunity to release
> some code changes.  Probably the most visible changes in this update are
> modification in how address hierarchy is calculated, a new technique for
> calculating the importance using wikipedia articles and a new system for
> deduplicating place and admin areas.  As a result of these changes
> nominatim now supports a few extra tags that were previously ignored:
> 
> 'wikipedia' tag [1] and its variants. Adding this allows nominatim to have
> a far better value for how important a place is which helps with the
> ordering, for instance a search for "statue of liberty" now consistently
> returns the correct one [2] first rather than the on on a traffic island in
> the UK [3].  If you find a place where the ordering of results is still bad
> consider adding suitable wikipedia links to the osm elements to help
> improve scoring.
> 
> The new version of nominatim also supports both 'label' and 'admin_centre'
> relation members for boundary relations [4] which allows it to reduce the
> amount of duplicated data returned and produce a more consistent result
> set.  The 'label' member will be merged (name and tags), relation tags win
> if there is a conflict. 'admin_centre' member will be merged only if the
> names and 'rank' (effectively admin_level / place=*) match, but other than
> that same rules.  In both cases the node will also be added as the centre
> point of the polygon - i.e. the location that the map will centre on and
> this is returned in preference to the geometric centre of the polygon.  If
> no 'admin_centre' and 'label' members are present the code will try to 
> guess by looking for a node at the right admin level, name and approximate
> location - obviously explicit tagging is far better and more accurate.
> 
> Thanks to all those who help with this update, in particular Sarah Hoffmann
> who did by far the majority of the work!

I was realy surprised, yesterday, after nominatim finally returned the results
in much better order and without duplicates.

Thanks a lot, this is a major enhancement.

Cheers
colliar

> 
> [1] http://wiki.openstreetmap.org/wiki/Key:wikipedia [2]
> http://www.openstreetmap.org/browse/way/32965412 [3]
> http://www.openstreetmap.org/browse/node/355219404 [4]
> http://wiki.openstreetmap.org/wiki/Relation:boundary#Relation_members
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