Question

Select the CORRECT option(s). Aerial images are prone to external geometric errors due to random movements of the aircraft, which involve changes in ______.

• A. altitude
• B. attitude
• C. terrain relief
• D. focal length

Hint:

Think about which exterior orientation elements (position vs angular tilt) change due to aircraft instability, as opposed to ground-related or camera-related parameters.

Answer 1

The Correct Option is A, B

Step 1: Identify the source of the error.
The question asks about external geometric errors caused by random, unavoidable movements of the aircraft during flight (turbulence, wind gusts, pilot corrections), not errors caused by the ground/terrain or by the camera itself.

Step 2: List what random aircraft motion changes.
An aircraft in flight is never perfectly stable. Random motion changes two exposure-station parameters at the instant each photograph is taken: (i) the flying altitude, because the aircraft rises and dips due to turbulence, changing photo scale, and (ii) the attitude of the aircraft (pitch, roll and yaw), because gusts and corrections tilt the camera axis away from vertical, introducing tilt displacement.

Step 3: Why (C) is wrong.
Terrain relief displacement is a real geometric distortion, but it is caused by the elevation difference of ground points relative to the datum, not by the aircraft's movement; it is a ground-related error, unrelated to flight steadiness.

Step 4: Why (D) is wrong.
Focal length is a fixed camera/lens property chosen before the mission; it does not fluctuate because of aircraft movement, so it is unrelated to random flight-dynamics error.

Step 5: Conclusion.
Only altitude and attitude change randomly due to aircraft instability, directly introducing scale variation and tilt displacement respectively. \[ \boxed{\text{Correct options: altitude and attitude}} \]