Warn about waterway=canal as areas

[naoliv]

I saw some closed areas tagged as waterway = canal
​https://wiki.openstreetmap.org/wiki/Tag:waterway%3Dcanal says that it's a linear feature only (ie, we should not use it on areas)

If I did the right math, we have 2243 canals as areas in OSM

Is it a worth test?

area:closed[waterway = canal] {
        throwWarning: tr("{0} should not be used on areas", "{1.tag}");
        suggestAlternative: "width";
        suggestAlternative: "waterway=riverbank";
}

[Klumbumbus]

Replying to naoliv:

If I did the right math, we have 2243 canals as areas in OSM

How did you calculate it?

[naoliv]

I did with the stupid way: downloaded every waterway=canal and validated it :-/

[Klumbumbus]

Do you still have this data availible? Can you extract all the suspicious objects (double click on the group in the validator tree to select them all) and attach the osm file here?

[Klumbumbus]

This test could be extended also for waterway=stream|ditch|river|drain.

I wonder if it could produce false positives. canal doesn't imply a flow direction, so closed ways could be possible. Also I wonder if the 4 canals at ​https://www.openstreetmap.org/#map=17/52.48587/13.49096 are corretly tagged as canal.

[naoliv]

The correct number is 2305 (I forgot to also test the relations before).

Without #13884, #13885 or #13887 I can't see an easy way to filter only the affected objects.

I can copy them in another layer, but they won't keep their OSM ids (#13885)
I can select all the ways and purge the rest, but for this I also need a way to select their nodes (#13887)

Do you know any other option?

One area with real examples: ​https://www.openstreetmap.org/way/374711923

[Klumbumbus]

Replying to naoliv:

I can copy them in another layer, but they won't keep their OSM ids (#13885)

Thats not important for this use case here (as long as you paste them at the source position). I just would like to check if I can find false positives in this dataset.

[Klumbumbus]

Replying to naoliv:

Do you know any other option?

I did't think about relations, but for ways you can do:

• select all affected ways
• add the tag xxx=yyy to the ways
• select all waynodes (I think requires utilsplugin2)
• add the tag xxx=yyy to the waynodes
• search for xxx=yyy
• invert selection by searching for -selected
• purge

[skyper]

+1

Waterways=river;canal;stream;drain;ditch only belong to unclosed ways and relations type=waterway. We uses different tags for water bodies like natural=water or waterway=riverbank.

[skyper]

Replying to Klumbumbus:

Replying to naoliv:

Do you know any other option?

directly download with overpass (no need to filter/purge)

I did't think about relations, but for ways you can do:

• select all affected ways
• add the tag xxx=yyy to the ways
• select all waynodes (I think requires utilsplugin2)
• add the tag xxx=yyy to the waynodes
• search for xxx=yyy
• invert selection by searching for -selected
• purge

Way to complicated !

1. create another empty layer
2. select objects
3. merge selected to empty layer

[naoliv]

Replying to skyper:

directly download with overpass (no need to filter/purge)

How can I select only the closed canals in overpass?
I am already using it (but downloading every canal)

I will try the merge selected option later.

[Klumbumbus]

Replying to skyper:

directly download with overpass (no need to filter/purge)

How do you select only closed ways in an overpas query? (The goal was an osm file with all closed ways (+relations) with waterway=canal with their current id)

1. create another empty layer
2. select objects
3. merge selected to empty layer

Yes, thats easier. I never used "merge selected" before :)

[skyper]

Replying to Klumbumbus:

Replying to skyper:

directly download with overpass (no need to filter/purge)

How do you select only closed ways in an overpas query? (The goal was an osm file with all closed ways (+relations) with waterway=canal with their current id)

Sorry, probably mixed up different search/filter.

Still found a solution with purge:

1. download all ways with waterway=canal (probably can only download from land mass)
2. search/select all unclosed ways
3. purge
4. download relations type=multipolygon waterway=canal

[naoliv]

Merge selected did a better job here.
Selecting -closed and purging them also removed the closed ways.

edit: I should have used type:way -closed, of course :-)

[Klumbumbus]

OK, we should exclude objects with area=no and or attraction=* to avoid false positives like ​way/175034247 or ​way/192657911. However it seems we can't avoid a few false positives for e.g. ​way/114691942 or ​way/225105909. (The last example is actually mapped wrong, but it could be a false positive if the multipolygon wouldn't be present.)

[naoliv]

Aren't ​way/192657911 and ​way/114691942 missing area=no?

[Klumbumbus]

You can add it, however this is not mandatory as far as I know.

[Klumbumbus]

...because waterway=canal is a linear feature only and not an area feature

[naoliv]

Then it won't be possible to distinguish this wrong canal ​way/230145073 from ​way/114691942, for example.

[Klumbumbus]

Yes thats what I was trying to say with "However it seems we can't avoid a few false positives for e.g. ​way/114691942 or ​way/225105909."

You can only know whether they are right or wrong from knowing the context. Both should be interpreted as linear ways. osm-carto fails there when it draws closed ways with waterway=canal as area by default. If it would draw it as linear feature we would probably have less wrongly as areas mapped waterway=canals :)

[naoliv]

I am opening a ticket in openstreetmap-carto

[naoliv]

At ​https://github.com/gravitystorm/openstreetmap-carto/issues/2424

I guess it's not possible to anything in JOSM then, right?

[Klumbumbus]

Replying to naoliv:

I guess it's not possible to anything in JOSM then, right?

I think we should add the test anyway. The relative and total number of false positives is very low. (This may change in the future, though.)

[Klumbumbus]

file from naoliv but with downloaded members of the multipolygons

[Klumbumbus]

In 11232/josm:

• fix #13877 - warn about linear waterway tags used on areas (modified patch by naoliv)
• fix #13879 - warn about values of tracktype other than grade1|grade2|grade3|grade4|grade5

[Don-vip]

Milestone renamed

[Klumbumbus]

Replying to naoliv:

At ​https://github.com/gravitystorm/openstreetmap-carto/issues/2424

This issue was just fixed.