On Mon, Sep 14, 2009 at 10:10 PM, Ulf Lamping ulf.lamping@googlemail.com wrote:
John Smith schrieb:
2009/9/12 Sarah Hoffmann lonvia@denofr.de:
I dare say that most of the ele tags in Switzerland are taken from the hiking posts at the moment, so I'd keep the CH1903 data for consistency. Maybe we should add a note in the wiki somewhere?
Actually that would make the data inconsistent with the rest of OSM then, wouldn't it be better to do ele=* for WGS84 and ele:ch1903=* ?
Question is: Is the assumption that ele is based on WGS84 any good?
I mean, ele is not meant to replace SRTM or other sort of elevation models.
ele is used (at least be me?) to tag specific places (e.g. in the alps) that intentionally has an elevation information.
That might be a mountain_pass, summit or alike where you can find a sign saying: "Stilfser Joch / 2758m". At least to me it doesn't matter what that information is based on (it should only differ in a few meters anyway).
This information is what you find "on the ground".
The wiki says use WGS84:
http://wiki.openstreetmap.org/wiki/Key:ele
But in practice people will just add whatever they find.
Adding ele:ch1903 when we know that the original is in CH1903 will help with accuracy since you know the original values from which the ele=* is derived .