Describing an elevation or height measured vertically from the geoid, which approximates mean sea level. Orthometric heights account for the Earth's curvature and local gravity variations, making them the standard for topographic maps and civil engineering projects where water flow is a primary concern.
Heard on the job
The GPS gives us an ellipsoid height, so we need to apply the geoid model to get the orthometric elevation.
Insider tip
GNSS receivers natively measure ellipsoid height. A surveyor must apply a local geoid model to convert this into a usable orthometric height.