Key:ele:wgs84

This is a tag for explicitly tagging a ellipsoidal height in the wgs84 system (World Geodetic System, Revision 1984). A well known problem of the values in the generic ele=* tag is that despite the definition, the reference isn’t homogeneous.

If used on areas and linear ways, the elevation must be true for the whole object. Otherwise use the tag on nodes.

Common errors

It used to be very vague whether this tag specifies a geoid height (using one of the EGM geoid models tied to WGS84's many revisions) or an ellipsodial height, until the altitude page has kind of clarified (but with great conflict with the other pages). The two values can be very different, on the order of tens of meters.

Generally, if the value you find on this tag is very similar to any mean-sea-level height, there's a good chance someone is doing it wrong. Look up the EGM96 geoid height over the area to make sure it's really not because the geoid happens to be near the ellipsoid, then move it to ele=*.

See also

• ele=* a generic ground elevation tag
• man_made=survey_point
• Proposed_features/ele:regional - a proposal to tag ele in the regionally common system and units
• layer=* - used to mark layering of map elements
• height=* - used to mark how tall a map object is
• alt=* - Proposal to mark exact altitudes concerning to the reference system of heights. Deprecated.
• ele:local=* unclear meaning
• World Geodetic System in Wikipedia