[OSM-talk] Zero point tag?

[Francois De Ryckel]

Yes Stefan!  This is what I meant: how would you tag the Kilometre_Zero?
(nothing to do with the geographic centre of countries)

Cheers

Francois




Stefan Baebler wrote:
> 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,
> Å tefan
>
> 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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François de Ryckel