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 <dieterdre...@gmail.com> wrote: > 2016-01-08 12:11 GMT+01:00 Colin Smale <colin.sm...@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 > _______________________________________________ > Tagging mailing list > Tagging@openstreetmap.org > https://lists.openstreetmap.org/listinfo/tagging > -- Dominic Coletti President & CEO 3Dreams Design 205 Anamoor Dr Cary, NC 27513 (919) 463-9554 NOTICE: This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.
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