Hi Daniel,
So you want to e.g. give the height of a bridge above the "mean high water spring" level of the river it crosses?
Yes.
use a qualifier. The unit would be meter
Yes.
The "elevation" property we have (P2044) is defined to refer to NN
It is not a good idea, to define 'elevation' like it is "defined" in P2044: there are hundreds of reference-levels (not only NN)...
NN was used from 1879 to 1992 in Germany.
Now in Germany we use NHN !
In other countries there are different reference levels changing in different epoches ...
you would need a more general "elevation" property, and a "reference level" property to use as a qualifier.
Yes, every elevation needs a reference level. (without a elevation measurement is not usable)
Then you could express something like "elevation: 28.3m;
In WD there is a confusion between altitude and elevation? (may be in American and British English? or geographic and aviation and astronomy?)
reference-level: Q6803625".
_reference-level_ could be: 'NN' 'NHN' 'LAT' 'MSL' 'MHWS' and a lot of others...
But this is a combination of unit and reference-level: 'm ü.M.'
We should not mix or confound this modellings...
What will be the WD-way? (you should discuss this with a geodetic specialist...!)
Additionally we need an expression for 'accuracy' and 'source': If the hight unit is 'meter' and the source value is in 'feet', the new value could have a lot more/less digits than the source, but no better/worse accuracy...
Bests, Markus
Am 27.09.2016 um 20:26 schrieb Markus Bärlocher:
Hallo Daniel,
nein, ich suche nicht einen WP-Artikel über MHWS, (diesen habe ich nur verlinkt als Erklärung)
sondern eine Einheit/unit, um MHWS als Bezugshorizont für geografische Höhen zu beschreiben.
MHWS wird verwendet, um Brückendurchfahrtshöhen über Wasser zu definieren, sowie für die geografische Höhe von Leuchtfeuern.
Mit herzlichem Gruss, Markus
Am 27.09.2016 um 19:28 schrieb Daniel Kinzler:
Am 27.09.2016 um 19:10 schrieb Markus Bärlocher:
I look for this: "Elevation in metres above 'mean high water spring' level."
Which means the geographic hight above MHWS: https://en.wikipedia.org/wiki/Mean_high_water_spring
By clicking on "Wikidata Item" in the sidebar of that page, I get to https://www.wikidata.org/wiki/Q6803625 ("highest level that spring tides reach on average over a period of time")
Is that what you need?