Stephen Hope (slh...@gmail.com) wrote:
I don't agree. This is a good general rule, but the general
convention on most maps is that the coast goes on the SEA side of
things like coastal swamps and mangroves. As a rule of thumb, if it
has plants growing though the water, it's land, not sea, even if it
happens to be wet.
Doing this your way looks OK at higher zoom levels, but as the
coastline way is used to make the country shapes for low zoom levels,
these ways are out of place. In most temperate areas, the difference
is so small you can't really tell, but this can be very important in
tropical areas where the mangroves can be many km wide. In these
cases, I've never seen a map that shows the coast on the inner edge,
and trying to do so is just wrong.
Stephen
So is there any consensus on where the coastline goes when you have
major areas of saltmarsh and/or mangrove? At the moment in OSM the
Abu Dhabi coastline follows dry land (i.e. above mean high water) and
there are huge expanses of mangroves and saltmarshes sitting in the
sea, e.g.:
http://www.openstreetmap.org/?lat=24.5191&lon=54.4942&zoom=13&layers=M
Google, however, has put the coastline around the outside of the
marshes and the result looks nothing like a good representation of
what's actually there:
http://maps.google.co.uk/maps?q=abu+dhabi&safe=on&ie=UTF8&hq=&hnear=Abu+Dhabi+-+United+Arab+Emirates&ll=24.521513,54.507294&spn=0.08215,0.241699&z=13 In fact, you can see island labels floating in the middle of apparently dry
land.
The trouble with putting the coastline around the outside of the
saltmarshes / mangroves is that it is very difficult to figure out
where this boundary is from aerial photography.
Dry land is usually easy to see. Obviously it would be better to
survey it in person, but given the shallowness of the water that would
be impossible unless you used a hovercraft or kayak.
--
Charlie
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