Autonomous electro-optical framing camera system, unmanned airborne vehicle

An aerial reconnaissance system generates imagery of a scene that meets resolution or field of view objectives automatically and autonomously. In one embodiment, a passive method of automatically calculating range to the target from a sequence of airborne reconnaissance camera images is used. Range information is use for controlling the adjustment of a zoom lens to yield frame-to-frame target imagery that has a desired, e.g., constant, ground resolution or field of view at the center of the image despite rapid and significant aircraft altitude and attitude changes. Image to image digital correlation is used to determine the displacement of the target at the focal plane. Camera frame rate and aircraft INS/GPS information is used to accurately determine the frame to frame distance (baseline). The calculated range to target is then used to drive a zoom lens servo mechanism to the proper focal length to yield the desired resolution or field of view for the next image. The method may be performed based on parameters other than range, such as aircraft height and stand off distance.