On the Atmospheric Refraction in Aerial Photogrammetry

We present an alternative, and possibly more intuitive, method for deriving the equation for correcting the atmospheric effect in near-vertical aerial images. For near-vertical images a horizontally stratified atmospheric model is assumed to be sufficient because the amount of error at the image plane is relatively small. Our derivation utilises Snell’s law and models the apparent uplift of a terrain point due refraction along the path from the ground object to the image. We show the approximate equivalence with older results in the literature, especially for aerial mapping flight heights under 7 km.