Bigger islands which consist of several coastline segments
I've just tried tagging like this on an island which is encompassed with several coastline segments, and since it is categorised as an area tag JOSM complains. Should a single point rather be used in such cases or is JOSM wrong to complain?--Guttorm Flatabø (talk) 16:22, 17 July 2013 (UTC)
I think JOSM is wrong to complain. I think the problem is that no strict 'area' data type exists in osm. Some back ground in this video: http://vimeo.com/79429403 --Hawkeyes (talk) 20:09, 8 October 2014 (UTC)
Multipolygon and coastline tagging
Can anyone more experienced correct the following for group of islands?
"Mf Relation.svg add the natural=coastline into a multipolygon."
This does not seem to be true and contradicts with what is written under http://wiki.openstreetmap.org/wiki/Tag:natural%3Dcoastline "Do not tag nodes or relations with natural=coastline."
Island vs. Islet
The criteria listed on the main page are:
- "with max. area of 1 km²" - this could be easily calculated by the renderer, but it cannot be that easily estimated by a mapper. I just came across an island with about 1 km² and wondered which tag to use. This criterion does not make any sense to me.
- "only a few buildings (or none)" - what is "only a few"? 5? 10? Can't the number of buildings be determined by the renderer, again? And is it really intended that big islands within the polar circle or with military use - in which cases they might be unhabited but nevertheless important - shall be tagged as islets?
- "located near by a bigger island or to the onshore" - just as above, this can be automatically determined.
- "if an island is in the middle of the sea and far away of other islands, cause the prominent meaning..." - The word "prominent" tells it all. It's just the same as with peaks, villages etc. The calculation of prominence is a rendering task, not a tagging task! Otherwise we would need to invent tags like "peaklet", "houselet", "meadowlet", and maybe the other way too using an augmentative suffix like the Italian "-one".
Why natural=coastline for an island?
An island (or islet) boundary represents exactly a coastline.
natural=coastline is useful (and required) for really large territories and with several administrative divisions that demands many breaks on the land border with the ocean. And by its own definition natural=coastline is only applicable to ways and not for areas (closed ways) so the use of this tag should not be proposed as a complement for islands.
An island is semantically complete in itself, so asking mappers to include the tag natural=coastline just creates a redundancy and adds an useless complexity. -- 16 June 2016 ThiPv
- This tag can also be used for islands in fresh water bodies like lakes, where the way surrounding the island will be a part of a multipolygon relation representing the natural=water of the lake. In the ocean an island needs natural=coastline to show that it is land rather than part of the sea, since the natural=coastline ways are used to make polygons representing the oceans or land, used by most database users. --Jeisenbe (talk) 22:00, 14 January 2020 (UTC)
Islands which don't always exist
Is there any tagging appropriate for islands that spend some of the time completely submerged? Also islands which vary enormously in size due to routine water level changes? -- Zcapw15 08:01, 19 May 2018
- If the island varies in size with the tides or water levels in a lake, then you should map the coastline or edge of the water at the high water level, for example, the mean high water line at spring tide for the coastline, or the seasonal maximum lake level for a lake.
- If you want to map areas of beach or tidal flats around the island, but between the low water level (at low tide for example) and the coastline, you can map these areas with natural=beach+surface=* for sand / pebble beachs, or natural=wetland+wetland=tidalflat for tidal flats. Exposed bedrock can be mapped as natural=bare_rock
- Shoals and reefs in the ocean which are only exposed at low tide are usually mapped as natural=shoal for sand or gravel bars or natural=reef for rock or coral reefs. You can also use the tidalflat tags mentioned above if appropriate.--Jeisenbe (talk) 13:18, 10 August 2019 (UTC)
Islands with lakes
There seem to be a few islands with a lakes/ponds in them wehre the ponds are tagged as "inner" parts of a multipolygon. This seems wrong to me unless there is good evidence the inner portion 'finds the same level' as the body of water surrpunding it. Would this be a suitable modification ot the page i.e. "Do not add ponds or lakes on an island as inner to the island if their water level differs from that of the surrounding water" OWTTE. The current page only menitons the situaiton where the island 'is a hole in' a lake. --InsertUser (talk) 21:48, 14 January 2020 (UTC)