[Tagging] Waterway length

[André Pirard]

On 2019-02-17 12:55, Eugene Podshivalov wrote:
> вс, 17 февр. 2019 г. в 00:11, André Pirard <a.pirard.papou at gmail.com 
> <mailto:a.pirard.papou at gmail.com>>:
>
>     It's easy to make a script to total up all the segments of a
>     waterway or any way.
>
>
> It will work but only if the entire river from its spring to mouth is 
> drawn precisely enough, all relation roles are labeled properly and 
> nobody breaks the labeling by intent or mistake some day.
> The more side streams a river has the greater probabily is to break it 
> one day.
> Here is an example of such complex river which name means "a river of 
> a hundred waterways"
> https://www.openstreetmap.org/relation/5561722#map=13/51.4077/25.2271
>
> Cheers,
> Eugene
>
The method I describe has the advantage that the length written in an 
OSM relation would be the only, or almost, number that shows exactly 
what it measures instead of other measures said better than others for 
no explained precise reason. The relation makes a consensus of what the 
river is, the number is right, and anyone having another conception of 
the river can explain it and compute the length difference the same way 
as the relation does.
Imprecision is to be corrected, just as I'm spending much time using 
JOSM to improve to a 20 cm precision errors of 3 to 5 m or more made 
with other editors.
I saved as a GPX file the relations that I found for rivers Le Rhône 
<https://www.openstreetmap.org/relation/1075117>, La Meuse 
<https://www.openstreetmap.org/relation/1075197> and Байкал road 
<https://www.openstreetmap.org/relation/318461> (going to Иркытск where 
a guy tried to sell me confiscated material such as cranes, lorries and 
railway wagons).
Anyone can use JOSM to make routes and save them as *.osm and *.gpx 
files without modifying OSM.

I tried to upload them to RouteYou <https://www.routeyou.com/>, but it 
would limit the length.
I uploaded them to GPSies 
<https://www.gpsies.com/#10_50.6167_5.75_mapnik> but the lengths are 
bogus, apparently multiplied by a strange factor.

GPSies
	real
	×
	GPSies name (by PapoudeOSM)
12,275.62 	614 	18 	OpenStreetMap La Meuse 
<https://www.gpsies.com/map.do?fileId=qmstzmvbysegiyua> (FR+BE)
15,052.41 	812 	20
	OpenStreetMap Rhône 
<https://www.gpsies.com/map.do?fileId=udauuravtkrjjxhp>
33,926.12 	1 113 	30
	OpenStreetMap Байкал road 
<https://www.gpsies.com/map.do?fileId=ieubgcbhgjcgbxia>


(Turn off waypoint display)

Anyway, that's the idea.

All the best,

André.


> вс, 17 февр. 2019 г. в 01:18, Sergio Manzi <smz at smz.it 
> <mailto:smz at smz.it>>:
>
>     Sorry for the typo: of course Wikip_*a*_dia was meant to be
>     Wikip_*e*_dia!
>
>     On 2019-02-16 23:15, Sergio Manzi wrote:
>>     Then why don't you submit a paper to the CNFG (http://www.cnfg.fr/) and correct the Wikipadia articles?
>>
>>     Sergio
>>
>>
>>     On 2019-02-16 23:07, marc marc wrote:
>>>     Le 16.02.19 à 22:32, Sergio Manzi a écrit :
>>>>     A static value for a river length in OSM, without any information about
>>>>     its source
>>>     every tag you add into osm have a changeset with a source tag, isn't it?
>>>     so adding the lenght should/must also have a source (extrapolation (sum
>>>     of all way of a relation) of osm data is a source)
>>>
>>>     a few month ago, I have checked the length of Rhône [1]
>>>     the french wikipedia list 2 sources for the lenght... both are very fair
>>>     away of the lenght found after some work on osm data.
>>>     which one to choose? osm without hesitation. maybe it is not fair but at
>>>     least it is verifiable (everyone can load the relationship, see the
>>>     result and correct errors if necessary) while the other 2 sources
>>>     (including the official French source) are totally unverifiable.
>>>
>>>     unfortunately I did not send in osm the result of the cleaning because
>>>     it concerned partly errors in osm (mainly roles in the relationship)
>>>     but I started by purging everything that didn't interest me in the
>>>     relationship before fixing. it will have to be done again
>>>
>>>     [1]https://en.wikipedia.org/wiki/Rh%C3%B4ne
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