Which equation defines ellipsoid height h in GPS terms?

Which equation defines ellipsoid height h in GPS terms?

• A. h = N + H
• B. h = N - H
• C. h = H - N
• D. h = N * H

Answer: (A)

In GPS terms, the ellipsoidal height h is obtained by adding the height above the geoid (orthometric height) to the geoid’s offset from the ellipsoid (geoid undulation). So h = H + N. This means you take the height above mean sea level (H) and account for how far the geoid sits from the reference ellipsoid at that location (N) to get the height above the ellipsoid (h). If the geoid is above the ellipsoid (positive N), h increases; if the geoid is below (negative N), h decreases. The other expressions would not reflect this direct additive relationship.

In GPS terms, the ellipsoidal height h is obtained by adding the height above the geoid (orthometric height) to the geoid’s offset from the ellipsoid (geoid undulation). So h = H + N. This means you take the height above mean sea level (H) and account for how far the geoid sits from the reference ellipsoid at that location (N) to get the height above the ellipsoid (h). If the geoid is above the ellipsoid (positive N), h increases; if the geoid is below (negative N), h decreases. The other expressions would not reflect this direct additive relationship.