Photogrammetry (tilted photograph): if the swing angle of a tilted aerial photograph is 230°, what is the rotation angle for the photo?

Introduction / Context:
In tilted aerial photography, three angular elements describe orientation: tilt, swing, and rotation. Swing is the azimuthal rotation of the photo about the vertical, while rotation is the orientation of the photo axes relative to the flight line. For many exam conventions, the rotation angle r can be related to swing S via r = |S − 180°| when the other tilts are modest.

Given Data / Assumptions:

• Swing S = 230° (measured from a reference direction, typically flight line).
• Standard academic convention: rotation r = |S − 180°| for this problem style.
• Other tilt components are not required for this simple conversion.

Concept / Approach:
The rotation aligns the photo axes with respect to the principal directions. With swing exceeding 180°, the equivalent acute rotation is the excess over 180°, yielding a compact angle in [0°, 180°].

Step-by-Step Solution:
Compute r = |S − 180°|.Substitute S = 230° → r = |230° − 180°| = 50°.Thus, rotation angle equals 50°.

Verification / Alternative check:
Rotation must be less than 180°; taking the minimal equivalent rotation confirms 50°.

Why Other Options Are Wrong:

• 130° or 140° do not match the standard relation r = |S − 180°|.
• 25° is half of 50°, not supported by the given definition.

Common Pitfalls:
Confusing swing with yaw; forgetting to subtract from 180° when S > 180°.

Final Answer:
50°