Photogrammetric rotations: Rotation of the camera at exposure about a horizontal axis perpendicular to the line of flight is called what?

Introduction / Context:
In aerial photography, the attitude of the camera at exposure is described by three small rotations. Correctly naming each rotation helps diagnose image tilt and plan block adjustments.

Given Data / Assumptions:

• Flight direction defines the longitudinal axis.
• Axes: vertical (yaw/swing), along flight (tilt/omega), and across flight (tip/phi).
• Small-angle approximations apply for near-vertical photos.

Concept / Approach:
Common terminology maps to photogrammetric angles: swing (or yaw, κ) is rotation about the vertical axis; tilt (ω) is rotation about the axis along the line of flight; tip (φ) is rotation about the horizontal axis normal to the flight line. The question specifies the last case, hence “tip.”

Step-by-Step Solution:
Identify axis: horizontal and perpendicular to flight → across-track axis.Match to photogrammetric term: rotation about across-track axis is “tip.”Therefore, select “Tip.”

Verification / Alternative check:
Many texts denote ω (tilt) about the flight axis and φ (tip) about the cross-flight axis; κ (swing/yaw) about vertical.

Why Other Options Are Wrong:
Swing/Yaw: vertical-axis rotation.Tilt: along-flight horizontal axis, not across-flight.None: not applicable because a standard term exists.

Common Pitfalls:
Using “tilt” generically for any non-vertical rotation; precise axis matters in block aerotriangulation.

Final Answer:
Tip.