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
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