How to create an Island in an ocean?

Help and support
1

Ive had a search and couldnt find anything relevant, I do know how work with groups inners/outers etc.

Ive tried to create small islands off the western coast of British Columbia, however, the coastline group it would need to be in, doesnt appear in the drop down list.

Could someone have a look at OpenStreetMap and tell me what I need to complete this?

2

Looks like reasonable tagging. A counter clockwise way with natural=coastline is all that is needed for an Island.

Geometry looks a bit off, from the aerial imagery I have available. Coastline in OSM follows mean high springs, and these smallet islets seem to include areas covered at regular high tide.

You’ve grouped these islets into a place=islet multipolugon, which is not unusual for collectively named rocks.

But having that relation as a member of the Brown Passage relation is not correct, use the coastline ways as inner members instead.

3

Thanks, I’ll give that a try.

They were previously just tagged as natural wood from a previous canvec import a long time ago, so I was trying to fix it.

4

Its intresting OSM is using MHWS for coast line, instead of chart datum - Lowest Astronomical Tide, as it would increase the chance of going aground, not that a professional mariner would use OSM for navigation.

5

Re: this point specifically, the iD editor (at osm.org) shows relations for which some member has been downloaded. So for example:

  • The vast majority of the time, the relation for the enclosing country boundary will not appear, unless you are editing close to the border (iD will download border geometry and then show the relation if you are close enough.)
  • Nearby turn restriction relations will typically be shown since the roads are likely downloaded and nearby
  • Smaller multipolygons will typically behave as expected since some nearby member geometry will be loaded still.

Just one of the quirks created as artifacts of tradeoffs the developers made between usability, performance, discoverability, and so on. :slight_smile: