The correct answer is: D. All of the above
The height displacement on a vertical photograph is the difference between the elevation of a point on the ground and the elevation of its image on the photograph. It is given by the following formula:
$h = \frac{f}{H}(x – x_p)$
where:
- $h$ is the height displacement
- $f$ is the focal length of the camera
- $H$ is the flying height
- $x$ is the horizontal distance from the principal point
- $x_p$ is the horizontal distance from the principal point to the ground point
As the horizontal distance from the principal point increases, the height displacement increases. This is because the image of a point on the ground that is further from the principal point will be projected onto a smaller part of the photograph, and therefore the height displacement will be greater.
As the ground elevation increases, the height displacement also increases. This is because the image of a point on the ground that is higher up will be projected onto a higher part of the photograph, and therefore the height displacement will be greater.
As the flying height increases, the height displacement decreases. This is because the image of a point on the ground that is further away will be projected onto a larger part of the photograph, and therefore the height displacement will be smaller.