Finding the range to a distant object near the sea surface

摘要

Within the marine atmospheric surface layer it is possible for a single camera to deduce passively the range to a point target. Although this range determination would appear impossible at first glance, such a measurement exploits the common occurrence of sub-refractive propagation conditions in the marine environment. A calculation of the range to an object utilizes a geometric optics determination of slight angular differences between two different ray trajectories to the object. This is most commonly done with the assumption of Euclidean or 'free-space' conditions. In this paper we utilize the phenomenon of inferior mirages to provide two different ray-paths to an imaging sensor. The primary assumption is that the environment containing the path from camera (or eye) to target is homogeneous (but not isotropic).