Exporting all the bodies of water for a Wiki photography competition

General talk
1

Hi all

I’m considering starting a Wiki Loves Earth photography competition (WLE is a very large open license photo competition run by Wikipedia volunteers) for bodies of water (seas and oceans + possibly bodies of water within each country).

I’ve got some experience working with Carto to import data to create the competition page using external data.
http://www.wikilovesearth.bio/english

I’m wondering how viable and technically complex it would be to extract the shapes from OSM to create a map for the competition? Does anyone know if there are any examples where something like this has been done before? I’m an occasional contributor to OSM so many guess is that the shapes could be filtered by type but beyond that I don’t understand.

Any and all suggestions very much appreciated.

Thanks

2

It’s fairly easy to extract shapes from OSM via Overpass Turbo (example for the Schaalsee nature reserve: https://overpass-turbo.eu/s/yux (just requires some familiarity with OSM tags etc.). Note that your poi for Schaalsee appears to be off by about 30 km and that Schaalsee isn’t even visible on your map.

Note that not all POI’s on your map are mapped in OSM, so you may need to put in some work to correct this where needed.

3

Thanks very much, this is really helpful. Do you know what the main types of tags I would have to include to make sure every type of body of water was captured?

4

Well, lakes are almost always tagget natural=water, but among the POI’s on your map I have also spotted islands as well as “archipelago’s” both in lakes and in the ocean. The latter is where things start to get somewhat trickier (With a few exceptions most ocean archipelagos probably isn’t mapped as archipelagos in OSM yet). There are also coastal areas for which you’ll probably have to make your own polygons

5

Wondeful, thanks very much, I’ll try and work it out and come back to you

6

OK, I’ve tried to run a query but I’m pretty stuck

  • How do I search for multiple types of area at the same time?
  • Clearly this is a really big query, can I just run it for the whole world and it just takes ages or is there some kind of limit on time or size of query?

Thanks

7

You want all lakes etc in OSM or just those concerning your POI’s / competition?

The various public Overpass servers tend to limit the amount of resources used per query, so complex queries will usually work for small areas only.

8

All lakes, rivers, seas, oceans etc for the whole world…

9

You might also need landuse=basin, though it’s not clear to me:

https://wiki.openstreetmap.org/wiki/Tag%3Alanduse%3Dbasin

10

Just for the record, there are about 8 million “natural=water” in OSM: https://taginfo.openstreetmap.org/tags/natural=water . Depending what you want to do with it you might need a very large server indeed…

11

Oh dear…

12

It’s a different question, but https://help.openstreetmap.org/questions/63484/find-features-eg-man_madechimney-exceeding-a-certain-size-limit which has just popped up on the help site is similar and an answer there (using overpass) might help you too.