[OSM-talk] Zero point tag?

[Stefan Baebler]

It might be that François wasn't talking about geographic centre of
countries, but established (read: old) reference points from times
where each country / region had their own coordinate system, or not
even real coordinate system, just measuring road distance from that
defined point.

http://en.wikipedia.org/wiki/Kilometre_Zero

enjoy,
Štefan

On Thu, May 15, 2008 at 8:52 AM, Mike Collinson <mike at ayeltd.biz> wrote:
> 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
>
>
>
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