[Talk-us] administrative boundaries and Nominatim
openstreetmap at brian.quinion.co.uk
Wed Aug 1 00:42:49 BST 2012
>> Is it sensible to have a polygon for the boundary and also a node that
>> locates precisely the cultural/logical center? Does Nominatim ignore
>> the node when there is a same-named boundary? Or is there some way to
>> have a relation for a town that has both a polygon and a center?
> Apparently you can add a node to the relation with role admin_centre.
New version of nominatim supports both admin_centre and label relation
members although it will also have a go at automatically merging them
even if they are not explicitly tagged.
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
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. This is a
new property in the xml and json format and will be release with the
While doing this people may also wish to ensure that there is a
wikipedia tag  which is now used as a basis to calculate relative
importance of admin features. Adding this makes the ordering of
results far better.
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