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I hope you can help me. How do you differentiate between geographical borders and political boundaries?

For Example: Relation 3028095 is a political border. It's not a coastline. Relation 27335 is a geographical boundary. As you can see in osm, it is exactly the coastline.

But the tags which are used don't indicate it. So how do OSM know if it has to display the relation as landmass or not?

Thank you very much

asked 03 Aug '15, 12:00

Xiakitl's gravatar image

accept rate: 0%

edited 03 Aug '15, 12:04

escada's gravatar image


as far as I can see both are administrative boundaries (type=boundary, boundary=administrative, admin_level = 4). Don't know why you think one of them is a coastline. See Coastline for more information about the coastline tagging

(03 Aug '15, 12:05) escada

Not sure what your question has to do with the first relation, it doesn't match any coastline.

The second relation is just an administrative border. For the coastline there is another relation which you seem to have missed.

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answered 03 Aug '15, 13:12

scai's gravatar image

scai ♦
accept rate: 23%

I'm not sure what you're asking. There isn't really any "coastline relations". For drawing the map, and showing land or water, a separate file is used that is updated almost daily. Read more here: Coastline.

Often coutries are drawn with their administrative borders including the surrounding waters. Some lower admin levels aren't, which explains how you see two relations one which has sea, and the other which doesn't.

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answered 03 Aug '15, 12:52

rorym's gravatar image

accept rate: 11%

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question asked: 03 Aug '15, 12:00

question was seen: 3,746 times

last updated: 03 Aug '15, 13:12

NOTICE: is no longer in use from 1st March 2024. Please use the OpenStreetMap Community Forum