OpenStreetMap
I just found a huge dam missing in Germany. This surprised me as I thought Germany was more or less “complete”. It had been an untagged line (http://www.openstreetmap.org/#map=17/51.11237/7.89440) until I added a name and the tag “waterway = dam” to it today.
In its immediate vicinity there are things to be found like
- a vending machine for excrement bags http://www.openstreetmap.org/node/681507482
- 2 Webcams http://www.openstreetmap.org/node/2975537573, http://www.openstreetmap.org/node/2975537574
- a bench http://www.openstreetmap.org/node/2954092511
but nobody noticed the dam wasn’t on the map.
Discussion
Comment from SimonPoole on 5 December 2015 at 00:26
The actual body of water has been mapped since 7 years. I suspect we didn’t even have a tagging for the dam itself at that point in time.
When we refer to Germany as being complete this refers mainly to the road network and the larger cities, outside of those areas there are still lots of details to be mapped, not to mention things like house numbers (we should be crossing the 50% mark in Germany very very soon).
Simon
Comment from MarkusHD on 5 December 2015 at 00:58
The dam was already existing since more than 4 years, just without the name: https://www.openstreetmap.org/way/105671446
Now there are two dams, the one above and your new one, which enclosed nearly the whole lake (because the untagged way you mentioned was merely used as outer boundary for the lake relation) before your second edit correcting it: http://www.openstreetmap.org/way/353892535
Comment from BCNorwich on 5 December 2015 at 07:38
So, Way: 105671446 In changeset: 18556757 Tags: “waterway”=”dam” should be removed.
Comment from Ortsangabe on 5 December 2015 at 09:46
Hello, thanks for the comments. So the dam wasn’t missing after all! To tell the truth, I don’t know what the best practice for dams is (that’s exactly why I looked at this particular dam: I have been adding some dams in Afghanistan and I was searching for existing examples for guidance):
So, should there be a separate line (like https://www.openstreetmap.org/way/105671446) that can’t be found because it is in the same place as the shoreline?
or, should it be integrated in the shoreline (like I it did with way http://www.openstreetmap.org/way/353892535, and messed on my first try, you’re right MarkusHD ), so it’s not a separate feature in its own right anymore?
Maybe the best thing would be to model the dam as an area, but that is difficult and would require more research (as the only consistently visible thing is the crest, and one can’t know the exact extent of the building below water without looking at plans).
Comment from lyx on 5 December 2015 at 10:39
I usually map dams as an area, but cheating by omitting the underwater part. Recent example would be http://www.openstreetmap.org/way/384134161
Comment from Ortsangabe on 5 December 2015 at 16:24
The “official” topographic map has a little strip that indicates the slope, which is nice:
It doesnt show the underwater part either, so it’s not cheating apparently. I couldn’t find a direct link for it https://www.geoportal.nrw.de/application-geoviewer/start/index.php
Comment from MarkusHD on 5 December 2015 at 23:57
There is no consensus about which of the two kinds of mapping is preferred, it also depends on the specific case. Usually I draw these duplicated ways instead of splitting the way and having to create a relation (e.g. for a lake as in this case).
In enhanced OSM editors like JOSM you can find and select all ways sharing nodes with other ways using the middle mouse button. Maybe this is not possible in iD, I don’t know.