[OSM-talk] Coastlines

[David Earl]

[I meant this to go to the list]

> -----Original Message-----
> From: talk-bounces at openstreetmap.org
> [mailto:talk-bounces at openstreetmap.org]On Behalf Of Artem Pavlenko
> Sent: 22 January 2007 11:16
> To: talk at openstreetmap.org
> Subject: Re: [OSM-talk] Coastlines
>
>
> Would it be more useful to join shorelines into polygons e.g
> create countries
> boundaries?
> Cheers,
> Artem


A good time to raise the issue again: the problem with coastlines is they
don't seem define which side is sea and which is land. And they don'talways
run in the same direction. So not only is it impossible to make islands or
land masses (not countries!), a renderer can't reliably locally render sea
as blue and land as white (or whatever), only draw a line.

The simple answer is to define sea as always on the right side and orient
all coastline segments appropriately; or if you must, then a separate tag to
say which side is which.

In many areas a renderer could heuristically guess which side is sea by the
density of land-based features to one side or the other of the coastline,
but that seems unnecessarily complicated.

Creating islands might be useful, but mst maps will be rendered at a scale
where you'll never see anything like the complete outline, so that in itself
woun't help local rendering.

David