[Tagging] Elevation and height on vertical features

[Dominic Coletti]

I've always thought of ele representing the lower part, which is clear for
man made features like buildings or obelisks (elevation of the ground, then
add height for the highest point at that spot). Now when it comes to
vertical elements like cliffs, where you have ground on both ends, it
admittedly becomes ambiguous, but my suggestion would be to define to use
the lower end also in these cases for simplicity/uniformity.

+1

On Fri, Jan 8, 2016 at 6:37 AM Martin Koppenhoefer <dieterdreist at gmail.com>
wrote:

> 2016-01-08 12:11 GMT+01:00 Colin Smale <colin.smale at xs4all.nl>:
>
>> Where do we go from here? Maybe we should encourage an explicit reference
>> to the datum used, such as ele:wgs84=* or ele:osgb=*?
>>
>
>
> this is what some people are already doing (not so few, but few compared
> to the total number of ele-tags):
> http://taginfo.osm.org/search?q=ele%3A
>
>
>> Or should we heuristically assume that no mappers will have translated
>> elevations to wgs84 anyway, and change the wiki to make the definition
>> into "national standards"?
>>
>
> -1
>
>
>> According to wikipedia [1] the differences between the datums can be up
>> to 100m.
>>
>
> that's the maximum, can you say something about the average/typical
> difference?
>
> This article suggests that the differences between the official European
> systems is (in case of Belgium almost) neglectible (see the comparison
> table):
> https://de.wikipedia.org/wiki/H%C3%B6he_%C3%BCber_dem_Meeresspiegel
>
> I didn't find a simple statement about the differences between WGS84 and
> DHHN92 (german system), but I found this talk in German that goes into the
> very details of the argument (posting it in case someone is really
> interested in details of the topic):
> http://www.lv-bw.de/lvshop2/Produktinfo/wir-ueber-uns/links/vortraege/DVW_Artikel_Normalhoehen_in_BW.pdf
>
> Cheers,
> Martin
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-- 
Dominic Coletti
President & CEO
3Dreams Design
205 Anamoor Dr
Cary, NC 27513
(919) 463-9554

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