Which height is commonly obtained from GPS measurements?

• A. Ellipsoidal height h.
• B. Orthometric height H.
• C. Geoid height N.
• D. True height.

Answer: (A)

GPS measurements give the geometric height relative to the reference ellipsoid, known as the ellipsoidal height h. The receiver solves for position in a chosen ellipsoid model (like WGS84), and the height component is the distance above that ellipsoid along the normal. To get orthometric height (height above mean sea level), you’d add a geoid model and compute H = h − N, where N is the geoid height. Geoid height itself isn’t directly measured by GPS; it comes from gravity data and geoid models. True height isn’t a standard GPS output in geodesy. So the height most directly obtained from GPS is the ellipsoidal height.