Question

The height derived or deduced directly from the GPS observations is referred as

• A. The sensitive height
• B. The plyometric height
• C. The variable height
• D. The ellipsoidal height

Hint:

GPS positions are computed with reference to a mathematical reference surface called the ellipsoid (such as WGS-84).

Answer 1

The Correct Option is D

Step 1: Recall the GPS reference surface.
GPS does not measure height from the sea. It works against a smooth mathematical shape of the Earth called the ellipsoid, such as WGS-84.

Step 2: See where the raw height comes from.
The receiver computes its position relative to this ellipsoid, so the height that pops straight out is measured from the ellipsoid.

Step 3: Name that height.
A height taken perpendicular to the ellipsoid is called the ellipsoidal height.

Step 4: Check the other options.
"Sensitive", "plyometric" and "variable" height are not standard survey terms, so they are wrong.

Step 5: Note the contrast.
The everyday height above mean sea level (orthometric height) is different and must be found by adding a correction.

Step 6: Conclusion.
The height got directly from GPS is the ellipsoidal height.
\[ \boxed{\text{The ellipsoidal height}} \]