Add Island Names

[rami-dv]

Islands are important and often notable map features, and island labels should be included in the tiles.

With the island's geometry (if it's a multipolygon relation), it should be possible to infer a reasonable minzoom for the label point, such as done in the planetiler openmaptiles profile. In that profile, the multipolygons are set with a minzoom depending on their area, while all label points are added at zoom 12.

Currently, island name points are the only data that I've needed, other than a protomaps extract, in order to make a solid basemap. The logic used in the OMT profile seems solid to me, and I think the island label points would fit in just fine in the physical_point layer.

[nvkelso]

Great idea, can you assemble a PR?

[bdon]

The OMT code is licensed differently from this repo and not license-compatible, so we can't derive any code from that.

Otherwise it should just be as simple as deriving a rank from the area? @nvkelso since we are getting rid of physical_point, which Tilezen layer would islands go in?

[nvkelso]

There isn't a license issue referring to Tilezen (@bdon rightly points out the OMT issue).

Tilezen does much the same thing but varies the zoom a bit and does archipelago, island, and islet here:

https://github.com/tilezen/vector-datasource/blob/master/yaml/earth.yaml

[bdon]

Yep, it would be best to inspect an existing Tilezen Tangram style (like https://demo.tangram.city/) to compare the behavior and see how closely we can derive the logic from the Python/YAML Tilezen code.

[nvkelso]

Walkabout is most relevant, fully featured style:

https://tangrams.github.io/walkabout-style/#15/37.7926/-122.4003

[wipfli]

Note sure how relevant it is for the discussion here, but I use QRank for island labels on https://wipfli.github.io/swiss-map/#map=8.61/42.4284/10.2657

https://github.com/wipfli/swiss-map/blob/e9f69c8088e1d7ee307bae6c35904ca20933145b/planetiler/src/main/java/com/onthegomap/planetiler/examples/QRank.java#L123-L126

There are issues though. For example the island relation for Sardigna does not point to the wikidata object of the main island, which has high qrank, but rather to the wikidata item of the collection of islands of Sardigna and the small neighbors which has low qrank...

[bdon]

nice San Juan islands example from bubble-wrap: https://tangrams.github.io/bubble-wrap/#10.029166666666685/48.5077/-122.6431