Render the flow direction of waterways

[23cpo]

I think it would be nice to see the flow direction of waterways on the map.

I like the rendering from OpenMapSurfer (arrow after the river name): http://openmapsurfer.uni-hd.de/?zoom=17&lat=48.68466&lon=13.10254&layers=B00000FFFF

[matthijsmelissen]

See also https://trac.openstreetmap.org/ticket/3198 - there we decided not to implement it, but we could reconsider that.

[imagico]

Having this shown would certainly greatly improve the quality of the waterway data in the long term, i.e. it would be good for use of the map as means of verification for the mapper (currently probably about 1-5 percent of the waterways are wrong in orientation). Since relief is not rendered in the standard style it would also be quite useful for normal map viewers.

The reason given in trac for closing is not convincing, the long term flow direction is nearly always clear, short time tidal reversals notwithstanding - unless of course the course of the waterway itself is rapidly changing which is a completely different problem.

[dieterdreist]

2014-06-12 0:16 GMT+02:00 schropps notifications@github.com:

I think it would be nice to see the flow direction of waterways on the map.

+1

[matkoniecz]

Reason for closing on track is rather strange and I completely disagree with it. I am neutral about rendering arrow - nice information and feedback but also even more clutter.

[matthijsmelissen]

I think it would be nice to see the flow direction of waterways on the map.

The problem is, do we think that way direction in itself is sufficient to derive flow direction from?

[Rovastar]

Yes, that is the correct way to map a river with the flow. http://wiki.openstreetmap.org/wiki/Tag:waterway%3Driver My only concern was if we wanted to render it. Probably yes if done without to much clutter and was subtle

[dieterdreist]

Am 16/giu/2014 um 00:49 schrieb math1985 notifications@github.com:

The problem is, do we think that way direction in itself is sufficient to derive flow direction from?

IMHO it is, this has been a convention since the early days.

[RobJN]

I agree that this would be a nice thing to add as it gives mappers the feedback required to check that the river has been mapped in the correct direction (according to the tagging rule). I'm not sure if there's a QA tool for checking for errors, but it should be relatively easy (water flowing uphill anyone?).

This has been shown on Ordnance Survey's historic "County Series" maps as a feathered arrow: http://www.british-history.ac.uk/image.aspx?compid=40955&filename=fig05.gif&pubid=271

[astoff]

Another thing that can be looked at when this is implemented is the name of rivers. They are tiny, even when the river banks are wide enough to fit a bigger label. (By the way, it seems that lakes and the like don't have their names displayed at all.)

[matkoniecz]

The problem is, do we think that way direction in itself is sufficient to derive flow direction from?

What about waterway=canal =drain =ditch? How canals, drains, ditches with no flow or with flow that changes are tagged?

Wiki at http://wiki.openstreetmap.org/wiki/Tag:waterway%3Dcanal seems to assume that canals have flow and its direction is constant ("Create a simple way in the direction of flow of the canal").

[RobJN]

Well they will have a flow (albeit very slow, and in the case of canals, dependent on locks being in constant use), but we can opt to only show flow direction on rivers and streams.

[kocio-pl]

What is the conclusion? Do we still want this feature?

[pnorman]

What is the conclusion? Do we still want this feature?

We've never decided if we want it or not.

[matkoniecz]

Having this shown would certainly greatly improve the quality of the waterway data in the long term, i.e. it would be good for use of the map as means of verification for the mapper (currently probably about 1-5 percent of the waterways are wrong in orientation).

I think that we are rendering rather too much and adding even more things is a bad idea. Also, if we still have so many waterways in wrong direction - it fits rather some QA tool.

Since relief is not rendered in the standard style it would also be quite useful for normal map viewers.

I am not convinced that it will outweigh even more clutter.

[imagico]

I still think this would be positive to add (and could be done in a subtle way without much clutter at least at the high zoom levels) but i also meanwhile think there are other aspects of waterways - intermittency (which we added after this issue was opened) and artificial vs. natural (which is not currently rendered) and showing all of this and flow direction could be too much and the semantics are more useful to show in the map because they can much less easily be analyzed through QA tools.

[mmmbai]

This feature is very useful. Please add it then we can see river flow direction.