[OSM-talk] Maritme borders

Jochen Topf jochen at remote.org
Mon Feb 9 23:33:49 GMT 2009

On Mon, Feb 09, 2009 at 08:01:12PM +0100, Gustav Foseid wrote:
> On Mon, Feb 9, 2009 at 7:01 PM, Jochen Topf <jochen at remote.org> wrote:
> > Simple rendering without need for the relation has been taken care of
> > in the comprehensive proposal by tagging the ways with admin_level. What
> > else do you need?
> You have taken care of the wrong part of rendering. It is easy to render the
> territorial waters border, but difficult not to.
> I have checked some widely used online maps (didn't bother to go digging
> through my paper maps):
> Google Maps: Does not render international maritime borders
> Mapquest: Renders baseline/internal waters at high zoom levels, land borders
> only at low zoom levels.
> Live Maps: Renders only land borders
> Yahoo Maps: Renders only land borders and (at low zoom levels) internal
> waters border between two countries
> Map24.com: Internal waters and land borders?
> Basically, it seems that most map makers prefer to treat maritime borders
> and land borders differently. I think taggin in OSM should make this well
> established practice easy, instead of making it easy to render the
> territorial waters and land borders the same.

Ok, I understand your point: You want to easily be able to only render
land based borders without looking at a relation. I can see one way of
doing this by rendering the border first and then the water, but thats
probably not the best idea as we don't have the water areas either. :-)

We could use maritime=yes on those borders. Makes more sense in my
opinion then boundary=maritime for those parts. If you are just looking
at rendering rules, both could be used.

But! There always is a but, isn't there. :-) When I look at popular
maps, a very common thing is to only paint part of the map boundaries in
the water. Normally only out from the coast for a few kilometers and
maybe between islands or so. Does that mean we have to tag those parts
differently? Maybe boundary=somewhat_important? Its nice to tag things
to make it easier for the renderers, but first we should tag them for
what they are. And the boundary out on the water is an administrative
boundary like all the others. So it should be boundary=administrative.
If you want to, you can add extra tags as hints to renderers.

Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298

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