On Mon, Sep 14, 2009 at 10:10 PM, Ulf Lamping
<ulf.lamp...@googlemail.com> wrote:
> John Smith schrieb:
>> 2009/9/12 Sarah Hoffmann <lon...@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 .
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