Question

What is the primary purpose of fiducial marks on an aerial photograph?

• A. To calculate urban land use
• B. To calculate atmospheric conditions during capture
• C. To establish a reference coordinate system on the photograph
• D. To measure valleys on the ground directly

Hint:

Remember: \[ \boxed{ \text{Fiducial Marks} \rightarrow \text{Reference coordinate system + Principal point} } \]

Answer 1

The Correct Option is C

Concept: Fiducial marks are fixed reference marks placed at the edges of an aerial photograph by the camera. They are used to establish the internal coordinate system of the photograph and accurately determine the principal point.

Step 1: Understand the purpose of fiducial marks. They help in
• Establishing the photo coordinate system.
• Locating the principal point.
• Performing photogrammetric measurements.

Step 2: Identify the correct option. Thus, \[ \boxed{\text{Fiducial marks establish a reference coordinate system on the photograph}.} \] Therefore, the correct option is \[ \boxed{(C).} \]