[OSM-dev] country boundary polygons

[marcus.wolschon at googlemail.com]

Hello Andy.

Have you looked at how I did this in:
http://travelingsales.svn.sourceforge.net/viewvc/travelingsales/trunk/osmnavigation/src/org/openstreetmap/travelingsalesman/navigation/traffic/

it is documented here:
http://apps.sourceforge.net/mediawiki/travelingsales/index.php?title=TrafficRuleManager

"
For each country this test involves first to check with the bounding-box of
the country. If we are not within the bounding-box, we cannot be inside
that country.

Next we test if the node or way is tagged with "is_in:country" or "is_in"
and contains either the country-name (case insensitite) or the uppercase
ISO3166 -code of the country.

Next we load the prepared border-polygon of the country and cache it.
Loading the polygon take a lot of time but checks with it are fast. 
"

I'll add a fourth step to be taken if the distance to the simple polygon
is below it's simplification-threshold and use the OSM-ways that make up
the
border in that section then.

It never compares against the full OSM border of the country.

Marcus

On Tue, 31 Mar 2009 13:48:27 +0100, Andy Deakin <andy.deakin at pcmend.net>
wrote:
> 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