Question

For two ground points \(A\) and \(B\) at the same elevation on a vertical photograph, the photo scale is determined by the:

• A. Ratio of focal length to flying height only
• B. Ratio of ground distance to flying height
• C. Ratio of elevation to focal length
• D. Ratio of photo distance to ground distance between \(A\) and \(B\)

Hint:

For a vertical aerial photograph, \[ \boxed{ \text{Scale} = \frac{\text{Photo Distance}}{\text{Ground Distance}} } \] or approximately, \[ \boxed{ \text{Scale} = \frac{f}{H} } \] when terrain is level.

Answer 1

The Correct Option is D

Concept: The scale of a vertical aerial photograph is defined as the ratio of a measured distance on the photograph to the corresponding horizontal distance on the ground.

Step 1: Recall the definition of photo scale. If \[ d_p=\text{Photo distance}, \] and \[ D_g=\text{Ground distance}, \] then \[ \boxed{ \text{Photo Scale} = \frac{d_p}{D_g}. } \]

Step 2: Apply to points at the same elevation. Since points \(A\) and \(B\) are at the same elevation, \[ \boxed{ \text{Scale} = \frac{\text{Photo distance}}{\text{Ground distance}}. } \] Therefore, the correct option is \[ \boxed{(D).} \]