With an ellipsoid height for a point derived by GPS of 567.4 ft and a geoid separation of 123.8 ft, what is the orthometric elevation for the point?

With an ellipsoid height for a point derived by GPS of 567.4 ft and a geoid separation of 123.8 ft, what is the orthometric elevation for the point?

• A. 300.2 ft
• B. 443.6 ft
• C. 520.0 ft
• D. 567.4 ft

Answer: (B)

Geoid height is used to convert GPS ellipsoidal height to orthometric height. The orthometric height H equals the ellipsoidal height h minus the geoid height N: H = h − N. Here, h = 567.4 ft and N = 123.8 ft, so H = 567.4 − 123.8 = 443.6 ft. Therefore, the orthometric elevation is 443.6 ft.

Geoid height is used to convert GPS ellipsoidal height to orthometric height. The orthometric height H equals the ellipsoidal height h minus the geoid height N: H = h − N. Here, h = 567.4 ft and N = 123.8 ft, so H = 567.4 − 123.8 = 443.6 ft. Therefore, the orthometric elevation is 443.6 ft.