1. A method of distinguishing, from a moving platform, stationary objects from moving objects, the method comprising: using a first detector mounted to said moving platform to obtain at least a first output representative of a target area; advancing the moving platform relative to the target area; using a second detector mounted to said moving platform to obtain at least a second output representative of said target area; and making at least two comparisons of said first and second outputs for said target area at least two different time intervals, to distinguish, in said target area, stationary objects from moving objects.