[OSM-talk] Beaches at lower zoom levels

Stephen Hope slhope at gmail.com
Thu Aug 19 09:24:41 BST 2010


On 19 August 2010 17:27, Malcolm Herring <malcolm.herring at btinternet.com> wrote:
>
> The usual convention (Ordnance Survey for example) for land maps is to use
> "Mean High Water". (Marine charts usually use "Mean High Water Springs" as
> their dry land datum.)

There are exceptions.  If a given area is covered in vegetation (eg
salt marsh, or mangrove swamps) then it is usually put on the land
side, even if it is technically below the high water mark.  Otherwise
you get situations where hundreds of meters of tangled plant growth
are treated as sea, which just seems totally wrong. I've never seen a
paper land map which listed a mangrove swamp as outside the coastline,
though some of the PGS data does list them that way. (I don't know
what marine maps do).

Stephen



More information about the talk mailing list