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! -- Brian [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 _______________________________________________ Geocoding mailing list [email protected] http://lists.openstreetmap.org/listinfo/geocoding
