OpenStreetMap

Missing water=lake tags

Posted by pangoSE on 5 November 2019 in English (English)

I found a lot of lakes in Sweden which has natural=water but not tagged with any water= tags like water=lake. Most of them (est. 98%) are lakes.

I just wrote this https://josm.openstreetmap.de/ticket/18297#ticket

This resulted in one of my biggest changesets to date: https://www.openstreetmap.org/changeset/76657579

I have now found these tags missing on 3 continents Eurasia, Africa and South America.

Note: be careful with bays like this one as these are currently tagged with natural=water and no water tag because we have no suitable it seems. I add water=bay to these because they are not closed of like lagoons.

Note2: also be careful of riverbanks not tagged with waterway=riverbank.

Note3: My current workflow is this:

  1. download country or part of country (<100 mb) from geofabrik.
  2. use osmconvert and osmfilter to extract the natural=water and drop water= & waterway= tags. I use .poly files to extract smaller areas from the large country files. See https://wiki.openstreetmap.org/wiki/Osmconvert#Example_using_a_polygon_file_from_polygons.openstreetmap.fr for how to do that. An example command I use is: “osmconvert sweden-191107.osm.pbf -B=norrbottens-län.poly –complete-ways –complete-multipolygons -o=out.o5m && osmfilter out.o5m –keep=”natural=water” –drop=”water=” –drop=”amenity=” –drop=”waterway=” >out.osm”
  3. open the filtered .osm-file in JOSM
  4. inspect all elements to see if any are clearly reservoirs and add fixme tags to uncertain ones.
  5. search like this: “natural=water and -waterway=* and -water=* and -wetland=* and -sport=* and -landuse=* and -surface=* and -golf=* -fixme=* and (type:way or type:relation)” to filter out any strange water areas.
  6. add water=lake to the rest and source:lake=manual review based on MAXAR

Comment from Tomas Straupis on 6 November 2019 at 13:44

This is from russian water tagging scheme. Original OSM water tagging scheme does not require ANY water tags. Therefore please do not offer people to break good existing data (not all countries want to use russian water tagging scheme).

Comment from pangoSE on 7 November 2019 at 05:44

@Thomas Hi, as I see it adding a tag specifying which function a body of water has cannot be a lowering of quality, quite the opposite actually. I started this quest because I wanted to answer the question: how many naturally formed lakes (bodies of water surrounded by land) are there in Sweden? This question is hard to answer if any kind of water is tagged natural=water only. Could you link to resources backing up your claim?

Comment from Tomas Straupis on 7 November 2019 at 06:40

In original OpenStreetMap water scheme types of waterbodies are defined in main tag. Lakes - natural=water, reservoirs - landuse=reservoir, rivers - waterway=riverbank, and then all smaller types like landuse=basin. No need for any additional tag. Adding pointless tags automatically by a script does not give any value.

Your decision is based on existing tags only (not on local knowledge or other sources), this means you already have all information you need? Why adding new tags then?

Introduction of russian water scheme (where everything blue is natural=water) was a very unfortunate and unwise one. It makes no IT sense at all. It brakes current usage and provides absolutely no benefit as it will barely be possible to somehow make tag everything with natural=water, even with iD editor pushing it on newbies so much.

Comment from pangoSE on 7 November 2019 at 07:38

Oh, I was not aware of that. What about lagoons and bays? How do we tag that using the old scheme?

I’m not convinced that the old scheme was better as it seems like a bad idea to use a main tag like natural=water to only mean lake.

I will discuss this on the tagging mailing list before proceeding with more edits. I lean towards deprecating landuse=reservoir in favour of water=reservoir and adding water= to all elements tagged natural=water.

Comment from pangoSE on 7 November 2019 at 07:49

@Tomas did you see this? https://wiki.openstreetmap.org/wiki/Proposed_features/Water_details Overwhelming majority for this way of tagging then it seems. Unfortunately landuse=reservoir have not been deprecated which is confusing I think.

Comment from Tomas Straupis on 7 November 2019 at 07:50

Don’t know about lagoons and bays. Never though of them as separate waterbodies. Lake is a naturally formed waterbody - therefore natural=water. You can try tagging list, but there have been multiple attempts do “deprecate” original OpenStreetMap water scheme in favour of russian water tagging scheme, but the later one simple does not have any advantages over the original scheme. And water is a very prominent object, used in 99% of maps, so changing it is unwise in IT sense - anybody with at least a minimal IT expertise (coders are not “IT experts”) would say that changing tagging of such a prominent feature is a bad thing.

Comment from Tomas Straupis on 7 November 2019 at 07:54

https://wiki.openstreetmap.org/wiki/Proposed_features/Water_details <- this is the unfortunate russian water tagging scheme proposal. Made by at that time newby with no IT expertise. Unfortunately it was not noticed and overturned in time and it is now still bringing chaos into OpenStreetMap water tagging. Nobody noticed this schema until iD decided to force using it.

Note: Zverik (proposer) agreed at the time of proposal that his water scheme will not deprecate original (and still more popular) OpenStreetMap water tagging scheme.

Comment from pangoSE on 7 November 2019 at 09:04

@Tomas I don’t share your concerns at all. This approved water scheme enables you to qualify what type of object/function the body of water is. I found many natural=water that are swimming pools and industrial reservoirs that are clearly mistagged. This means that currently if you try to estimate the number of naturally formed lakes in the world from our data you have a lot of problems with mistagged elements.

We can do better. A MapRoulette challenge for every natural=water without water= or waterway= would probably be a good idea. :)

Comment from Tomas Straupis on 7 November 2019 at 09:41

If a pool is mistagged with natural=water you have to change it to appropriate tag like landuse=basin, not add another tag. You can tag anything you want with original OpenStreetMap water scheme, natural=bay or natural=lagoon can be your friends. You do not have to push a new scheme which has NO advantage over existing scheme. You can tag exactly the same types of waterbodies with new russian schema as with the original one.

Anybody thinking of changing such a prominent schema should think how THEY will spend THEIR time updating thousands of usages in maps, analysis, tests, documentation and how THEY will communicate this change to all users of OSM. Thinking that a lot of OTHER people would have to spend their time because of some geek idea is just selfish, irresponsible and IT-wise illiterate.

We need a MapRoulete challenge to find all water=* tags and correct them to appropriate tags like landuse=reservoir, waterway=riverbnak, landuse=basin etc.

Comment from pangoSE on 7 November 2019 at 10:28

I disagree. The tagging of swimming pool was changed to leisure=swimming_pool. See https://wiki.openstreetmap.org/wiki/Tag:landuse%3Dbasin

If you believe that introducing water= was a mistake I invite you to state it on the tagging mailing list and perhaps create a new proposal on the wiki to clean up the mess.

Comment from Tomas Straupis on 7 November 2019 at 11:28

A mess with water tagging was discussed a number of times in a lot of different places during those unfortunate years of existence of russian water schema :-(

Comment from pangoSE on 7 November 2019 at 12:13

@Tomas It sounds like you have given up. The only discussion I found on tagging was from 2011 but I did not search very thoroughly. Maybe you disagree about the whole subtags discussion as well? I like when we can agree on something and move forward. Sometimes I disagree with stuff but often I am convinced by the arguments.

I have one more example of unfortunate tagging with natural=water (that makes it render on the map but is data quality wise quite useless): https://www.openstreetmap.org/way/76372599 All the “water” = waterslides in there are tagged natutal=water ONLY. Can we agree that this is not optimal? Can we agree that when I want the number of lakes in cyprus and search for natural=water and gets these in return something is wrong? I believe that both iD and JOSM until recently lets this pass without complaining. In JOSM we just added a validation that would have catched this.

Comment from Tomas Straupis on 7 November 2019 at 12:40

The problem currently is in governance (in my opinion). There should be: a) restriction of change of prominent features (which would have prohibited change of original OSM water tagging scheme, it could prohibit in future changing say highway tagging, as there are a number of ideas how it could have been made better). This part could be easy. b) decision such as this is purely IT stuff, it must be done by people with actual IT experience, not by coders/geeks. This part is very problematic to implement for a number of reasons.

As for slides those are really nothing natural so cannot have natural=water tags. I would tag them with landuse=basin. So you can see that everything you want can be tagged with one tag. There is no point of introducing a scheme with pointless tag natural=water which says nothing, because you then need a second tag.

Important point: water scheme works now, you can already tag all different types of waterbodies. So there are no problems with original water tagging scheme -> no point of changing it, deprecating, introducing new schemes etc. There are much more useful thing to do.

Comment from pangoSE on 7 November 2019 at 15:21

I’m sorry but I disagree again. A quick search on the wiki brought this up: https://wiki.openstreetmap.org/wiki/Tag:attraction%3Dwater_slide which I think is a good tag for this thing. Basin is something completely different as you can see on the wiki.

I disagree with keeping the tagging scheme stale when it is clearly not detailed enough. As the database gets richer and richer and more and more detailed drone and orthography becomes available we will need to revise broken/cumbersome schemes.

I really like the water= tag because it is easy in an editor like JOSM to list the different values. That means I dont have to remember as many tags in total.

Comment from Tomas Straupis on 7 November 2019 at 16:12

Water slide tagging is not in my interest field, I’m not discussing about it specifically. My point is that for every water feature you have a tag to use without resorting to breaking huge amount of existing products.

I’m objecting to adding pointless water= tags semi-automatically and I’m also against usage of duplicate russian water tagging scheme in general.

How is original OpenStreetMap water scheme “stale”? What are you unable to map with it?

JOSM has a menu for water features and you can access all of them in one place, so no problem here as well.

Comment from pangoSE on 7 November 2019 at 16:50

You are suggesting, if I understand correctly, to change the definition of the following: natural=water = only “natural” water lakes is tagged with this landuse=reservoir = water surface not a lake, man_made landuse=basin = any water surface not covered and not a lake, not a reservoir

Is that correct? As I stated above this is very unprecise. I want a precise, well maintained geodatabase with a tagging scheme that helps adding more details. E.g. I invented water=bay for the specific purpose to tag bays (sv, da fjord) as that are mostly covered by land but connected to the sea, thus nor a lake nor a lagoon.

In my editing the last two days I found loads of riverbanks only tagged with natural=water. Do you know why? Because it shows up blue on the map. I think I am going to suggest to CartoOSM that they stop rendering elements only tagged natural=water to create an impetus for editors to be more precise.

Right now their meaning according to the wiki is:

natural=water * can be tagged along amenity=fountain (= not a lake) * can be tagged along water= tags * can be added along other tags specifying wasteplants etc. * if it has no other tags it is unclear what it represents

landuse=basin * An area of land artificially graded to hold water. Note that this definition includes also structures typically without water. Usually these features are made for man made water courses e.g. storm water, water treatment.

landuse=reservoir * Man made body of stored water. May be covered or uncovered. Usually formed by a dam over a natural water course, water then backs up into a natural valley or depression. Equal to natural=water + water=reservoir

As an aside JOSM adds the tags from the approved proposal we are discussing. I’m fine with that but I guess you are not. E.g. if you choose reservoir it adds natural=water + water=reservoir.

Comment from Tomas Straupis on 7 November 2019 at 17:28

Some very basics of IT: we are not creating a database from scratch here. There are already billions of objects and most importantly millions of different products created. Therefore doing a change which has a huge impact on those millions of products requires a very good reason and a clear benefit as such change will require months and maybe years of working time of many people to update their products.

You can imagine going to one of users of OSM and saying: - please change all you water code, we’re changing the scheme. They would ask: - why? what is a benefit of a new change? I will have to spend a lot of time to update. What would your answer be? “tags look prettier to me”?

You can tag all same classes of objects with original OSM water schema, so no benefit here. Names of tags is insignificant detail which is only important to geeks/coders - not important at all to final product (say high quality government geodatabases use codes like gc04 instead of human readable tags and then have comprehensive descriptions on what those tags mean). Therefore switching to new scheme provides NO advantage whatsoever.

In JOSM if I add reservoir from menu it adds landuse=reservoir. But there is another option which adds russian schema tags. JOSM gives mappers a choice. iD does not.

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