[OSM-talk] Placenames in Iceland - upcoming bill

[Martin Koppenhöfer]

Am 12.01.2013 um 02:21 schrieb Svavar Kjarrval <svavar at kjarrval.is>:

> What do you think?


Great news if they'd release the data for all these geographic place names.

From a practical point of view if they'd do so tomorrow we would probably not be ready to import it. There is no established tagging scheme for this kind of objects (mostly), and in some circumstances (very big areas) we might not even have an adequate data model. The bigger the areas get, the less precise (sharp) are usually the borders (if its not a coastline or a river), often these areas fade one into another. So it might be better suited to have a separate shape file with rough area limits instead of having the same areas in the OSM db. Of course point data could be an alternative for osm ("somewhere here is a valley called foo") but obviously nodes would be rather suboptimal to represent huge areas. The well established tags for these type of objects are natural=peak and bay and place=locality in wider use, and there is a proposal for features in mountainous areas (ridge, mountain range, …) all the rest would have to be invented and established.

The main reason why this wasn't done until now is IMHO what I wrote above: our current geometric representations are not very suited for this kind of information. Some time ago we had a discussion about this on the German ML and there was the idea of an additional datatype, a relation, which contained some objects like existing ways and nodes, and thereby described a rough area without explicitly delimiting it (you'd compute the actual area in preprocessing by drawing a hull around the members). This kind of object would be quite stable (if there are enough members in it), and it would weigh little in the db. As a variant you might also have roles like in and out to have the possibility to state that something is still or not any more part of the area.

cheers,
Martin