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Should islands/islets be the inner border of natural=bay areas?

Recently, Gulf of Bothnia ( between Sweden and Finland was changed from a single node into a huge multipolygon area. This has lead to some problems on several map services. For example both Mapbox and Wikimedia Maps seem to treat natural=bay as a water area, resulting in all of the islands turning invisible on their maps.

Due to the sheer amount of islands, to me it seems almost impossible to add all of them as inner boundaries of the natural=bay area.

I am familiar with the concept of "don't tag for the renderer", so I wonder what is correct mapping in this case? Should Gulf of Bothnia be changed back into a node or should it stay as an area?

asked 15 Sep '18, 19:10

Milwen's gravatar image

accept rate: 0%

edited 15 Sep '18, 19:22 says:

"There is currently no definitive rule if small islands within a bay should be mapped as part of the bay or if they should be excluded of the bay area as inner rings of the corresponding multipolygon relation."

Hence, I doubt we will get a good "answer" here. I can think of pro and con for each solution. I think this question should rather be discussed in the forum or mailing list or wiki talk page. If you take this discussion elsewhere, please mention a link here.

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answered 15 Sep '18, 20:35

aseerel4c26's gravatar image

aseerel4c26 ♦
accept rate: 18%

edited 15 Sep '18, 20:37

The answer is an obligatory YES no matter whether a related discussion is going on or on which forum the question has been asked. In the mentioned example there are over 3120 islands missing in the uploaded bay/fiord feature in an MP format like here (when clicking, please wait, it is a huge MP to render) Rendering this object will cause a serious damage to a map like here even if it is used only in lower scales. Besides the missing islands there are other bad side effects like here roads over water, strange stripes like here probably caused by unsynchronized generalisation, and so on. To get a correct map, most of the map-makers ignore the bay feature but then we just have a huge data redundancy in the OSM source database. By the way, if a user insists on the fiord area feature, it could be resolved by only two nodes. A program can create the perfect MP area on-the-fly in no time, just like I did to detect the mentioned missing islands.

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answered 29 Sep '18, 09:51

sanser's gravatar image

accept rate: 5%


meta: could you please not use the shorted URLs but full URLs? Use [foobar]( markdown's link formatting (→ foobar). Helps keeping the links working forever and avoids tracking by the link shortening service.

(29 Sep '18, 10:33) aseerel4c26 ♦

Thanks. I will.

(29 Sep '18, 12:54) sanser

Please, sanser, I want help with a related question I asked on the openstreetmap forum :

(26 Apr '20, 20:52) PhilippeC20

"Because it will break some map" isn't a good reason to suggest not mapping things in a certain way. Unfortunately here it's not really clear what is "correct" (my preference would be a single node for the bay, but that's not really relevant here).

(26 Apr '20, 21:54) SomeoneElse ♦

@PhilippeC20 - I provided an answer to your forum question just now.

This was meant to be a comment under sanser's reply but it ended up here. Sorry.

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answered 27 Apr '20, 01:39

AlaskaDave's gravatar image

accept rate: 16%

edited 27 Apr '20, 01:42

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question asked: 15 Sep '18, 19:10

question was seen: 2,126 times

last updated: 27 Apr '20, 01:42

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