We had some confusion in the German community with the ele-Tag.
Is this the “official” definition of the ele-Tag?
http://wiki.openstreetmap.org/wiki/Key:ele
In Ireland it seems that the ele= tag carries the WGS84 altitude,
different from ele:local=
In Germany the ele= tags carry the local values (above sea level, N.N., NHN, DHHN92).
I think also the Wiki is not clear, because WGS84 knows two different altitude
systems:
- height above GRS 80-Ellipsoid
- height above EGM96-Geoid (corrected according to local gravity field)
So, what’s the correct definition?
As an example: NMEA defines altitude over EGM96 geoid in the
altitude field. There is a 2nd field with the geoidal separation, that
the ellipsoidal heigth can be computed easily.
We need an exact definition.