[OSM-talk] Zero point tag?

[Mike Collinson]

At 05:00 AM 15/05/2008, Francois De Ryckel wrote:
>Hello everyone,
>
>How would you tag the "zero point" of a country?
>
>Shouldn't be an important tag as distances in a country are measure from
>that point?
>
>Thanks for the advices.
>
>
>François de Ryckel

François,

I don't know if this will suit your particular requirements, but I've published a list of "country bounds" here which includes a centre lat/lon:

http://wiki.openstreetmap.org/index.php/User:Ewmjc/Country_bounds

This was generated from US government (public domain!) GNIS data.  This is a dataset of several million location points around the world conveniently categorised by country.  I simply calculated a bounding box for each country and then the centre point of that box.

I then generated about 80% of the OSM place=country tags using the centre point to locate the tag.  The OSM database should now have a tag for every country in the world (at least as defined by the US government).

There are some inaccuracies though and I am working on  a version two.  In particular, I included marine features which makes several boxes too large, and may throw the centre point to a strange location.  Once I have this sorted, I intend to add a lat_max ... lon_min or some such tags to the country tags.  You could then derive a "zero point" directly from the OSM database.

Mike