Maniphest T199469

Islands and other map features hidden by bays
Closed, ResolvedPublic
Actions

Assigned To

Authored By

	Haros
	Jul 12 2018, 6:43 PM

Description

In the OpenStreetMap maps imported to Wikimedia, bays can hide islands within them. An example of this is an island Gressholmen just outside Oslo, Norway. The island itself is not visible on the map, but zoomed sufficiently paths and houses on the island can be seen underneath the water. Links to maps below.

I asked about this on the Norwegian mailing list for OpenStreetMap, and learned first that this was probably because there was modelled a bay there. Later that this apparently is a common cause and that it is common that users of OpenStreetMap gets this wrong. However I was told that the community around osm2pgsql have a way to deal with it. The fact that this island is clearly shown on OpenStreetMap.org testifies to that.

There are other cases I managed relatively easily to find, eg. close to Stockholm.
I don't know if Tag:natural=bay is a unique case.

Example Gressholmen (Wikidata Q952279):

Wikimedia:

https://maps.wikimedia.org/?lang=nb#16/59.8837/10.7188

OpenStreetMap.org:

https://www.openstreetmap.org/?mlat=59.8824&mlon=10.7173&zoom=15#map=15/59.8824/10.7173

OpenStreetMap.org item for the island:

https://www.openstreetmap.org/way/4154441#map=16/59.8825/10.7187

OpenStreetMap.org item for the bay:

https://www.openstreetmap.org/relation/6812187/#map=11/59.8064/10.7206

Related Objects

Mentioned In: T198027: Problems with rendering seashore areas

Event Timeline

Haros created this task.Jul 12 2018, 6:43 PM

Restricted Application added subscribers: jeblad, Danmichaelo, jhsoby, Aklapper. · View Herald TranscriptJul 12 2018, 6:43 PM

I just came across an example that is worse than some small islands outside Oslo.

Look at https://maps.wikimedia.org/?#9/60.1798/19.5790 and then zoom in one step from level 9 to level 10 and you drown the home of nearly 30 000 people.

Haros mentioned this in T198027: Problems with rendering seashore areas.Jul 23 2018, 6:12 PM

I found a patch that may be relevant.
https://github.com/pnorman/openstreetmap-carto/commit/30c6383dd364a7bfbabdf3322407570dce8f4977

What made me think it is relevant is the problem it claims to fix:
https://github.com/gravitystorm/openstreetmap-carto/issues/164

We don't have the resources right now to work on this, and it is probably solved on the new maps styles.

Reflecting reality on the priority.

Please keep an eye on the community wishlist later this and vote for better map styles!

Pikne merged a task: T198027: Problems with rendering seashore areas.Dec 21 2018, 6:21 PM

Pikne added subscribers: Sturm, • Mholloway, Pnorman.

It seems that Gressholmen now displays as the surrounding bay area object has been edited to exclude it. However as per natural=bay wiki page it isn't required to exclude islands. I still see quite some missing islands overlapping bay areas (w648202691, r9048910) around Estonia.

Inspired by openstreetmap-carto patch mentioned above, I gave it a try:
https://github.com/kartotherian/osm-bright.tm2source/pull/69

@Pikne thanks for working on top of that, I will take a look! Were you able to test it? I am asking out of curiosity because I am working on a Docker-compose environment for Kartotherian.

In T199469#4841159, @MSantos wrote:

@Pikne thanks for working on top of that, I will take a look! Were you able to test it?

No. I hope that someone else can test it.

This is great, a nice Christmas present to us all.

I don't know how I could test it, but if you need a place that has not been changed and where the problem is still visible, try
https://maps.wikimedia.org/?lang=nb#17/59.33994/18.44622

Compare with
https://www.openstreetmap.org/#map=15/59.3411/18.4445

Or you can look at https://maps.wikimedia.org/?lang=nb#10/60.0587/20.1572 or https://no.wikipedia.org/wiki/Mariehamn where there are some problems with Åland.