lionel.giard at gmail.com
Thu Jul 19 12:19:12 UTC 2018
I would also add that "water=reservoir" is a sub-tag of "natural=water";
while "landuse=reservoir" is a tag that can go alone by itself. The main
thing is that the second scheme is older than the first, and thus still
Looking at the proposal to "simplify water tagging" that was approved a few
years ago (
https://wiki.openstreetmap.org/wiki/Proposed_features/Water_details ), the
new scheme is to use *natural=water + water=** on most of the water related
For the reservoir/basin that don't always contain water (*especially for
storm water retention !*), we already have another tag : "landuse=basin"
that is for *" An area of land artificially graded to hold water." * so it
already cover this part and the sub-tag here are clearly made to describe
storm water retention/infiltration and some other artificial uses like that.
Thus, the landuse=reservoir tag is mostly an older scheme that still exist
and evolve as there are a lot of use in the database. Maybe should it be
discouraged to simplify the water tagging ? At the end, it doesn't really
matter that much for data users as it is only two schemes that say exactly
the same things (with the same sub-tag "reservoir_type=*"), it is more a
complexity in the database that could probably be avoided.
2018-07-19 10:08 GMT+02:00 Warin <61sundowner at gmail.com>:
> On 19/07/18 16:53, Mateusz Konieczny wrote:
> 18. Lipiec 2018 16:02 od eric at eric-poehlsen.de:
> The present OSM meaning of landuse=basin is "An area of land artificially
> graded to hold water."
> This does not distinguish it from water=reservoir
> OSM defined as "A reservoir or artificial lake used to store water."
> I think it should have the word "temporarily" add to read
> "An area of land artificially graded to temporarily hold water."
> I see it as similar to the bathroom basin - it holds water, but not all
> the time.
> Have you checked what is mapped? If mappers use both tags in the same way
> redefining them on wiki without resurveying most of them is pointless.
> I have not 'refined' them. I have simply stated the usual configuration.
> It is done to help mappers differentiate between them.
> As both are rendered the same the effect is negotiable.
> Dams are usually seen in imagery. And the larger of them are mapped. So
> that can confirm that no reservoirs are mapped as basins.
> I would expect reservoirs have been mapped for some time in OSM and basins
> only recently so there will be a fair few basins mapped as reservoir.
> This is a practice of 'best fit' and at worst 'tagging for the render'. I
> possibly have a few of them...
> If future renders distinguish between them then mappers will have
> motivation to correct any errors.
> At the moment that motivation is very small.
> Where someone has used both tags on the same object there is a problem...
> which is it?
> In that case I would first consult the history - what was it originally
> tagged, and then look at imagery for possible confirmation.
> If the imagery is poor then I'd go with the original mapper. Contacting
> the relevant mappers is also a possibility.
> Tagging mailing list
> Tagging at openstreetmap.org
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