[OSM-dev] country boundary polygons

[Andy Deakin]

Hi,

No major breakthrough here, but if anyone is interested in a quick and 
dirty 'what country is lat,lon in' I have created a simple method.

Lookups have been taking about 0.00002 seconds, and it involves a binary 
lookup file (25MB) at 1/20th of a degree resolution. Boundaries need 
further processing for an exact result. If you were only interested in a 
smaller area (e.g. Europe) then it could be made much smaller.

Details available here:
http://www.handyandy.org.uk/blog/2009/03/31/what-country-are-you-in/

Andy
>> Hi,
>>
>> I am looking for a simple answer to the question 'what country is 
>> lat+long in?', and for this I need the country borders as polygons.
>>     
>
> For the technical part, I had extremely good and fast (~0.1s) result with one 
> single postgres/postGIS query :
> echo "select osm_id,name,admin_level from planet_osm_polygon where way && 
> transform('SRID=4030;POINT(6.0333 45.7666)',900913) and 
> _ST_Contains(way,transform('SRID=4030;POINT(6.0333 45.7666)',900913));" | 
> psql gis
>  osm_id |     name     | admin_level
> --------+--------------+-------------
>   -7407 | Haute-Savoie | 6
>   -8655 | Rhône-Alpes  | 4
>  -74368 | Cusy         | 8
> (3 rows)
>
>