Surface effect subtraction for airborne underwater target identification

Surface reflection is an impediment to effective optical detection of underwater targets for two reasons. It obscures targets by interfering with the line of sight and it can cause anomalous detections that increase false alarm rates. The first step in improving airborne underwater target detection is selecting a proper polarization filter that selects light that is returning from sub-surface objects. This reduces line of sight problems and reduces false alarms. Remaining false alarms can be reduced in number by utilizing the surface returns that were rejected in the first step. Detection processing of a different polarization filter that gives mostly surface related detections can be used to filter the final detection list.