[OSM-newbies] Reverse geo coding

Michael Handerek osm at handerek.net
Thu May 28 10:06:51 BST 2009


Hi,

I am new to osm. I am currently developing a prototype of a reverse
geo
coding tool based on a local osm db. The input has to be a
latitude/longitude pair and the output a human readable address.

I already handled it to extract the street name and postal code of a
lat/long pair using the tags of a nearest-neighbor-node. To do this
with
a acceptable query time i use the k-nearest-neighbor algorithm
(http://www.bostongis.com/?content_name=postgis_nearest_neighbor_generic#130).

Now I have to get at least the country and city name. In order to do
this i see two possibilities.

1. Searching for the nearest city node, in order to extract the
information from his tags.

2. Creating geometries for each continent, country and city in order
to
check if nodes are within.

May someone know some better method to get the needed information,
feel
free to discuss.

The 1. possibility, also used by 'Where are they' 
(http://wiki.openstreetmap.org/wiki/Where_Are_They), for me, seems to
be
imprecise.

Regards,
Mic

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