Incorporation of atmospheric blurring effects in target acquisition modeling of thermal images

Abstract

Recent investigation of atmospheric modulation transfer function (MTF) in the thermal IR has shown significant spatial frequency dependence. This dependence is related to aerosol forward scatter as well as particulate absorption effects, shown to be primary contributors to blur in thermal imaging through the atmosphere. One of the primary models for target acquisition is the Institute for Defence Analysis variant of the Night Vision Laboratory (IDA/NVL) target acquisition model; in this paper, this model is revised to include atmospheric MTF spatial frequency dependence. It is shown how the target acquisition probabilities and, conversely, the range at which targets can be detected are changed by the inclusion of atmospheric effects. Under weak turbulence conditions target acquisition probabilities are better than predicted by the IDA/NVL model at shorter ranges. For very strong turbulence, as at midday on hot days, target acquisition probabilities decrease. Effects of real-time image restoration are discussed.