[OSM-talk] National borders - mapnik

Thu May 29 10:35:13 BST 2008

Steve Chilton wrote:
>Sent: 28 May 2008 10:01 PM
>To: Beau Gunderson
>Cc: talk at openstreetmap.org
>Subject: Re: [OSM-talk] National borders - mapnik
>
>See example from UK: http://dev.openstreetmap.org/~steve8/borders.jpg
>Border between countries England and Scotland is one way (actually probably
>several ways), tagged admin_level=2.
>Border between counties Cumbria and Northumberland is another way/s, tagged
>admin_level=6.
>Implicitly the country border is part of the collection of ways that make
>up the Cumbria county border.
>There is only one border there, and there only needs to be one "way".
>NB: If you want polygons for areas you probably have to post-process the
>data to compile them or use relations to group them.

This issue comes up with quite a lot of tags. Bus routes for instance where
you have more than one route reference running along the same way. In that
instance I use a "|" between each route reference, could we not do the same
for admin_level data? ie add all the numbers that are relevant, because in
some cases perhaps lower ones do not exist for the location.

Cheers

Andy

>
>Cheers
>STEVE
>
>	-----Original Message-----
>	From: blodulv at gmail.com on behalf of Beau Gunderson
>	Sent: Wed 5/28/2008 9:14 PM
>	To: Steve Chilton
>	Cc: talk at openstreetmap.org
>	Subject: Re: [OSM-talk] National borders - mapnik
>
>
>	Please clarify one thing:
>
>	   "any border that is both a state and national border should be
>tagged at the highest level (in this case national, admin_level=2)"
>
>	To me this sounds like there is just one way for the state/national
>border... but...
>
>	   "and the state borders will come in too, with their appropriate
>style."
>
>	This sounds like there are two ways, one for the state border and
one
>for the national border.
>
>	This seems to make the most sense to me given the second sentence
>quoted above.
>
>
>	Beau
>
>
>	On Wed, May 28, 2008 at 2:06 PM, Steve Chilton
><S.L.Chilton at mdx.ac.uk> wrote:
>
>
>		Logically, any border that is both a state and national
border
>should be tagged at the highest level (in this case national,
>admin_level=2).
>		Similarly in UK any border that is both county and country
>should be tagged at highest level (country, admin_level=2).
>		That way all the country borders will show at designated
zoom
>levels. When you move to a level that state (or whatever) comes in the
>country border will already be there (in its appropriate style) and the
>state borders will come in too, with their appropriate style.
>		Currently there is an /Else filter which picks up borders
that
>have no admin_level set, but it necessarily doesn't come in till higher
>zooms, which appears to the case for your example below.
>
>		Cheers
>		STEVE
>
>
>		-----Original Message-----
>		From: blodulv at gmail.com on behalf of Beau Gunderson
>		Sent: Wed 5/28/2008 8:42 PM
>		To: Steve Chilton
>		Cc: talk at openstreetmap.org
>		Subject: Re: [OSM-talk] National borders - mapnik
>
>
>
>		       The US national border with Canada is all tagged with
>admin_level=4, border_type=state, border=administrative... It also has the
>left/right countries (at least the bit I looked at in WA did).
>
>		       How should state borders that are also national
borders
>be tagged?
>
>		       Does setting admin_level=2 fix the whole problem?
>
>		       As you can see, they're not currently visible at low
>zooms:
>
>		          http://www.openstreetmap.org/?lat=48.83&lon=-
>118.46&zoom=7&layers=B00FF
>
>
>		       Beau
>
>
>		       On Wed, May 28, 2008 at 1:21 PM, Steve Chilton
><S.L.Chilton at mdx.ac.uk> wrote:
>
>
>		               The latest mapnik stylesheet has the National
>borders moved from coming in at z10 to coming in at z7. Now zooms to z6
>show the borders as thin blue lines taken from the shape files, and then
>switch to OSM data at z7 using a slightly thicker purple line.
>		               Not all borders show, for one of two reasons
-
>either they are not digitised or are not tagged appropriately.
>		               So, it would be useful if folk have a look at
>their own country/area at z7.
>		               Does in show correctly?
>		               If not:
>		               1 - check whether it has been digitised. If
not
>- is there a valid, non-copyrighted source for putting in the border
>alignment.
>		               2 - check whether it is tagged
>boundary=administrative, admin_level=2. If not - change the tagging to that
>so that it may show.
>
>		               As a reminder, admin boundaries should be
tagged
>for the admin_level that they are (at the highest level). Country/national
>borders are always admin_level=2. Internal borders should be tagged
>according to the suggested schema for that particular country. Details are
>on the wiki at:
>
>http://wiki.openstreetmap.org/index.php/Key:boundary
>		               which also explains the accepted way to tag
for
>the countries on either side of the border.
>
>		               Cheers
>		               STEVE
>
>
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