[OSM-talk] Tagging Seamarks

Malcolm Herring malcolm.herring at btinternet.com
Tue Aug 17 10:42:53 BST 2010

The data models specified in:

(more will follow as we progress)

are all part of the OpenSeaMap project. They define a namespace with
tags beginning "seamark:". These tags are rendered in the OpenSeaMap 
overlay by that project's tile server with its own stylesheet. They were 
not intended for use by the OSM or other renderers, though of course, 
anyone is free to make use of them.

The rationale behind creating this distinct namespace is that they are
rigorously structured on the object and attribute catalogue of the IHO
S-57 standard. As they then have a one-to-one correspondence with that
catalogue, they can easily be converted into the S-57 interchange data
format, which is used by marine chart plotters and other navigation
equipment and databases.

The freietonne project, which is mainly oriented on inland waterways, 
have their own tagging scheme that they have designed for their 
particular needs. Our two interests overlap, particularly in river 
estuaries, so nodes with both types of tagging are to be found. This 
does not present a problem to either project, so the result is that we 
can share survey data (i.e. the longitude/latitude of nodes), but each 
can tag for their own needs.

Since these tags relate to nodes not used by OpenStreetMap, "we" (i.e. 
the OSM community as a whole) do not have to decide on one scheme or 
another since it has no impact on the map. Therefore the proposal & vote 
are moot.

Malcolm Herring

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