CH Geodesy & Coordinate Systems 2

Question 1

Which ellipsoidal parameter defines the degree of flattening of a reference ellipsoid?

Accepted Answer

Inverse flattening (1/f)

Answer

Inverse flattening (1/f) directly expresses how much the ellipsoid departs from a perfect sphere, and is a defining parameter for datums like WGS 84 (1/f ≈ 298.257).

Question 2

In the context of hydrographic surveying, what does the term 'geoid undulation' (N) represent?

Accepted Answer

The difference between ellipsoidal height and orthometric height

Answer

Geoid undulation N = h − H, where h is ellipsoidal height (GPS) and H is orthometric height (leveling), and it varies globally from about −105 m to +85 m.

Question 3

A hydrographer converts UTM coordinates to geographic coordinates. Which projection property is preserved in UTM?

Accepted Answer

Conformal (angle-preserving)

Answer

UTM is based on the Transverse Mercator projection, which is conformal, meaning small shapes and angles are preserved locally.

Question 4

What is the central meridian scale factor (k₀) used in the standard UTM projection?

Accepted Answer

0.99996

Answer

The standard UTM k₀ = 0.99996 reduces distortion so that scale error stays within ±0.04% across the 6° zone width.

Question 5

Which geodetic coordinate is measured as the angle between the equatorial plane and the normal to the ellipsoid at a point?

Accepted Answer

Geodetic (geographic) latitude

Answer

Geodetic latitude is the angle between the equatorial plane and the ellipsoidal normal at the point, which differs from geocentric latitude except at the poles and equator.

(CH) Certified Hydrographer Practice Test

(CH) Certified Hydrographer Practice Test

CH Geodesy & Coordinate Systems 2