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FOSSGIS @amapanda@en.osm.townI've added a new feature to WaterwayMap.org: Loop/cycle detection!
It shows all places where `waterway`s (e.g. rivers) form a loop, and go around in a circle. Most of these are simple tagging mistakes. Please get mapping!
map: https://waterwaymap.org/loops/
#OpenStreetMap #WaterwayMapOrg #RiverMapping #QA
general discussion on the OSM Forum: https://community.openstreetmap.org/t/the-wonders-of-early-medieval-fore-abbey-and-osm-river-topology-today-i-e-waterwaymap-org-is-going-around-in-circles/107497
or github issue tracker: https://github.com/amandasaurus/waterwaymap.org/issues
This tool, unlike the main WaterwayMap.org maps, takes the *direction* of the underlying OSM way into account. Simple rivers being split around a island won't be detected
@amapanda looking forward to this finding the canonical Charybdis
@amapanda Sometimes a navigable waterway=link canoe=yes exists inside a lake around an island, like way 1171031305 and peers near 45.542294/-78.590579. Is the error here one of *way direction* only (reverse it), or boats should only travel on one side of the island (delete a way segment) or something else (change tags)?
@ellie I've fixed that by removing `waterway=link`.
There are several `waterway` tags that can go in cycles, e.g. `=ditch`.
@amapanda Removed waterway=link from the loop detection algorithm's consideration or removed from the ways? (I don't see edits on the ways so either cached or the former...)
[Looks like https://www.openstreetmap.org/user/scarapella/history/ has a lot of waterway=link tags added recently. Also I see https://wiki.openstreetmap.org/wiki/Proposal:Tag:waterway%3Dlink exists as of recently.]
@ellie the waterwaymap loop detection ignores waterway=link now
@amapanda cool beans
@amapanda This has led to me digging up a 5 year old changeset discussion and taking another stab at getting the loops out of this wetland area. https://www.openstreetmap.org/changeset/66725627#map=17/44.07445/-123.26166
@amapanda I wonder why this area and waterway=fish_pass is being flagged https://waterwaymap.org/loops/#map=18.15/50.716291/6.446711 Look good to me…
Update: Also https://waterwaymap.org/loops/#map=17.57/50.744427/6.40097
@tordans 1st one: The OSM Wiki for fish passes says that the linear way is the waterway=fish_pass. For the area (which will have a loop), one should use water=fish_pass.
So that's a tagging mistake
@tordans 2nd example: I think that should be another `water` tag, .e.g `water=pond` or `=lake`.