How is the scale (S) of an aerial photograph calculated?

The scale of an aerial photograph is calculated by taking the ratio of the camera height to the focal length. This method operates on the fundamental principle that scale in photography is a relationship between the distance in the photograph and the corresponding distance in the real world.

When considering aerial photography, the scale is defined as the relationship between the distance measured in the photograph (image distance) and the actual distance on the ground (real-world distance). The camera height represents how high the camera is positioned above the ground, while the focal length indicates the distance from the camera lens to the image sensor.

Thus, when you take the ratio of the camera height to the focal length, you effectively determine how much distance on the ground corresponds to a unit of measure in the photo. This ratio provides an accurate scale that indicates the level of detail captured in the aerial photo, as well as how to interpret measurements taken from it.

This understanding is crucial for making accurate calculations in survey work, enabling surveyors to translate measurements from the aerial image into real-world dimensions that can be utilized for various applications such as mapping or land use planning.