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Areal Photo Scale

Determining the aerial photograph scale based on an aerial photograph and the measured ground size of objects

Scale of an aerial photograph tells us how much the ground has been reduced to fit onto the photo.

👉 To find it, we need two things:

  1. The size of an object on the photograph (for example, a road or a building measured in centimeters on the photo).

  2. The real size of the same object on the ground (measured in meters or kilometers).

Formula:

Scale=Ground distance/Photo distance

Example:

  • A road measures 2 cm on the aerial photo.

  • The real road length on the ground is 200 m (which is 20,000 cm).

Scale = 2/20,000 = 1:10,000

So the scale of the photo is 1:10,000, meaning 1 cm on the photo = 10,000 cm (100 m) on the ground.


  • Measure on the photo.

  • Measure the same on the ground.

  • Divide photo size by ground size.

  • Express as a ratio (1:n).


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