Altitude

Please also see ele=* for tagging elevation data. Altitude is usually referred to as the height above ground.

Please translate de:Altitude.

Thanks, --Markus 06:27, 8 June 2009 (UTC)

Stuff

The main discussion before was about how different systems use different zero level, and why, and what chaotic system we do use. For proper altitude coding we have to know the zero level (reference), the height difference from zero and the measure used; also we usually ought to know the proper reference for the zero level, the geoid and the reference ellipsoid used. We hardly ever seem to do.

There is a detailed description about measurement methods: calculating from mean or reference sea levels, barometric measurement and such.

Attributes

The standard of OSM is measured in meters based on the WGS84 ellipsoid:

• alt:wgs84=####.#

Be aware that this is not the same altitude one usually encounters on maps or public signs!

However we may have other systems (all measured in meters), say:

• alt:msl =####.# (Mean Sea Level)
• alt:etrs89=####.# (European Terrestrial Reference System 1989)
• alt:evrs =####.# (European Vertical Reference System)

And national -German-speaking :) - ones like:

• alt:nn =####.# (Normalnull)
• alt:nhn =####.# (Normalhöhennull)
• alt:dhhn92=####.# (Deutsches Haupthöhennetz 1992)
• alt:müm =####.# (Schweiz: Meter über Meer)
• alt:müa =####.# (Österreich: Meter über Adria)