[OSM-dev] Advice sought on polygon-with-hole drawing

Andy Robinson (blackadder) blackadderajr at googlemail.com
Fri Mar 14 09:01:18 GMT 2008

I'll admit and apologise that I haven't been following this thread too
closely, but from skimming over the surface wanted to make a couple of

The way we currently draw coastlines, as a boundary between the landmass and
a body of water sitting within the landmass is no different from the
position with lakes. If we think of the world as essentially a solid land
and that we have seas, oceans and lakes suck into it we can perhaps remove
some of the complexity of what is being discussed.

If we were to say that the boundary between land and a water body,
regardless of type, was to be treated in the same way that we now treat
coastlines, would we not have a straightforward method of tagging for

That leaves the issue of rendering order so that land that pokes through an
enveloping body of water gets rendered last. Surely the layer facility deals
with that?

I appreciate that some will wish to associate all the different edges of a
water body (outer and multiple inners), but we have relations for that.

If I've got this all wrong then someone point me to better understand the



>-----Original Message-----
>From: dev-bounces at openstreetmap.org [mailto:dev-bounces at openstreetmap.org]
>On Behalf Of 80n
>Sent: 14 March 2008 8:49 AM
>To: dev at openstreetmap.org
>Subject: Re: [OSM-dev] Advice sought on polygon-with-hole drawing
>What we need is some decent test data.
>Anyone fancy a mapping party in Luzon?
>On Fri, Mar 14, 2008 at 6:45 AM, bvh <bvh-osm at irule.be> wrote:
>	On Fri, Mar 14, 2008 at 02:06:04AM +0100, Frederik Ramm wrote:
>	> > Merkaartor fully supports them (both in editing and rendering)
>	> Good to know. So for a lake with an island, Merkaartor only
>	> tags on the relation, and neither on the lake circumference way
>	> the island circumference way?
>	Yes. And when an operator uses the 'create area' tool to make
>	such constructs, this actually his how merkaartor will suggest
>	tagging.
>	cu bart
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