Norway Community consultation - straits (Omsundet vs. Rensviksundet)

Hello OSM Norway,

There is a strait called Omsundet (Relation: ‪Omsundet‬ (‪7792570‬) | OpenStreetMap), which encompasses a smaller one, Rensviksundet (Way: ‪Rensviksundet‬ (‪737954164‬) | OpenStreetMap).

I would like to inquire and consult the community if Rensviksundet should be “excluded” from the Omsundet relation. I’ve noticed an error during editing, possibly due to duplicated features or overlapping straits.

Thank you,

I perceive it as unproblematic that a bigger strait can encompass a smaller strait. There’s no difference between straits and bays that I can think of in this regard. It is also common for bigger bays to encompass smaller bays.

I take more issue with the collection of islands that haven’t been excluded from the bigger strait. Maybe there’s controversy about this, but I feel like a “strait” can only refer to water cover, and not land within said water cover.


Thank you @harahu
We will excule that since it was the intended focus of our edit. However, we encountered a JOSM validation error related to the covering straits.

I would recommend to just put a node in the middle of the strait, or an unclosed way along the strait. They are far easier to maintain.

I do not see any reason why a small strait cannot be “inside” a large strait.

Slightly off topic: Similar issues have previously been mentioned about bays, fjords, peninsulas, etc.
The issue is that if we replace it by a node or a single line, the importance/size of the strait/bay/fjord/peninsula is much harder to define.
When it is made as a polygon or multipolygon, you can quite easily calculate the (approximate) area of the feature and use the size to determine at which zoom level you should render the name and e.g. how large or dominant the name should be.

For an example, look at how Reitstøen managed to do that for the various parts of Jonsvatnet: Jonsvatnet (when you zoom in, names will appear for the smaller bays, straits and peninsulas).

Similarly, for Trondheimsfjorden and its multiple bays of various sizes: Trondheimsfjorden (Trondheimsfjorden and Strindfjorden appear at z8, Korsfjorden and Gaulosen appear at z9, but Ilsvika, Korsvika and Leangbukta appear first at z13 since they’re a lot smaller)

These relations do not have to follow the coastline perfectly, so for large features like Sognefjorden it can be a very simplified polygon instead of a very complex multipolygon. That reduces the maintenance issues.

Personally I’m a fan of doing the naming of e.g. woods and parts of woods in a similar way, with simplified multipolygons. Then the rendering engines can determine when, where and how to render the names of each area, such as Nordmarka and Østmarka in this example: Oslo
When you start zooming in, you will be able to discover Krokskogen, Lillomarka, Skimarka, etc. in smaller fonts than Nordmarka and Østmarka. This is automated.

I’m aware that some people disagree in how this is tagged.


A simplified polygone is fine. It is easy to edit in iD for most mappers.

The extent of bays and straits for nodes and ways/lines is determined based on the distance to the coastline.

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Thank you @NKA , @anderfo @harahu

As a final conclusion on the straits, it seems that it is more tending towards capturing them as polygons, so we can probably exclude the islands.

Yes, just exclude the islands.

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