What are the different methods of scale determination ?

There are three methods of determining the scale :

1. By establishing relationship between photo distance and ground distance : In this method if additional information like ground distance of two identifiable points in an aerial photograph is available it is simple to work out the scale of a vertical photograph.

2. By establishing relationship between photo distance and map distance : If a reliable map is available for the area shown on an aerial photograph it can be used to determine the photo scale.

3. By establishing relationship between focal length and flying height of the Aircraft

We can determine the photo scale provided the information about the focal length of camera and the flying height of the aircraft are known.