Autonomous electro-optical framing camera system with constant ground resolution, unmanned airborne vehicle therefor, and methods of use

A method of autonomously imaging a scene with a reconnaissance camera system in a manner so as to continuously generate successive images of said scene meeting field of view, resolution, or image interpretability rating objectives for said images, said aerial reconnaissance camera system installed on board a reconnaissance vehicle and comprising a electro-optical imaging array, a zoom lens, and a camera control system for said array, comprising the steps of:

• a) generating first and second successive images of said scene with said electro-optical imaging array and storing said images in a sequential image processing circuit;
• b) supplying vehicle information to said camera control system from a navigation system on board said aerial reconnaissance vehicle and responsively correlating said first and second successive images to generate range information between said imaging array and said scene;
• c) retrieving information stored in said camera control system as to field of view, resolution, or image interpretability rating objectives for imagery to be generated by said imaging sensor;
• d) processing said information as to field of view, resolution, or image interpretability rating objectives, together with said range information derived from correlation of said first and second images and navigation information for said reconnaissance vehicle, to generate commands for a zoom lens drive system so as to adjust the focal length of said zoom lens such that said field of view, resolution, or image interpretability rating objectives are achieved;
• and
• e) exposing said imaging array to said scene to thereby generate a third successive image,
• whereby said third successive image achieves said field of view, resolution, or ground-resolvable distance objectives without real-time operator involvement, and while compensating for changes in attitude and altitude of said reconnaissance vehicle between initial expected values of said attitude and attitude during exposure of said array to said scene and the actual altitude and attitude of said reconnaissance vehicle when said array is exposed to said scene.

A method of autonomously imaging a scene with a reconnaissance camera system in a manner so as to continuously generate successive images of said scene meeting field of view, resolution, or ground-resolvable distance objectives for said images, said aerial reconnaissance camera system installed on board a reconnaissance vehicle and comprising a electro-optical imaging array, a zoom lens, and a camera control system for said array, the method comprising the steps of:

• (a) supplying navigation and range-to-target information to said camera control system;
• (b) retrieving from a memory information as to field of view, resolution, or image interpretability rating objectives for imagery to be generated by said imaging array;
• (c) processing said information as to field of view, resolution, or image interpretability rating objectives, together with said range information, to generate settings for said zoom lens so as have a focal length such that an image generated by said array will achieve said field of view, resolution, or image interpretability rating objectives;
• (d) adjusting the focal length of said zoom in accordance with step (c), and
• (e) exposing said imaging sensor to said scene;
• whereby said image achieves said field of view, resolution, or ground-resolvable distance objectives without real-time operator involvement and compensates for changes in attitude and altitude of said reconnaissance vehicle between initial expected values of said attitude and attitude during exposure of said array to said scene and the actual altitude and attitude of said reconnaissance vehicle when said array is exposed to said scene.

An unmanned aerial reconnaissance system capable of generating successive images of a scene meeting field of view, resolution, or image interpretability objectives without real-time operator involvement, comprising:

• A. a reconnaissance vehicle having a navigation system and a means of propulsion capable of flying said vehicle in a reconnaissance mission without on-board human operation;
• and
• B. an aerial reconnaissance camera system installed aboard said vehicle, comprising:
• an electro-optical imaging array comprising an array of pixel elements arranged in a plurality of rows and columns;
• a zoom lens system, comprising a zoom lens for imaging a scene external of said aircraft onto said imaging array and a drive system for adjusting the focal length of said zoom lens;
• and
• a camera control system for said imaging array and said zoom lens system, comprising:
• i.) a memory storing information as to field of view, resolution, or image interpretability rating objectives for imagery to be generated by said imaging array;
• and
• ii.) a camera control computer for receiving (a) aircraft navigation generated by said navigation system and (b) either range-to-scene information from a source of range information on board said aircraft or aircraft stand-off distance to said scene and aircraft height data,
• iii.) said camera control system further comprising a zoom lens adjustment circuit generating commands for said drive system for said zoom lens to adjust said focal length of said zoom lens in response to said either said range-to-scene information or said aircraft stand-off distance and aircraft height data, and navigation inputs received by said camera control computer and said information stored in said memory,
• iv.) said commands for said drive system for said zoom lens accounting for changes in attitude and altitude of said reconnaissance vehicle between initial expected values of said attitude and altitude during exposure of said array to said scene and the actual altitude and attitude of said reconnaissance vehicle when said array is to be exposed to said scene;
• said camera control computer, zoom lens adjustment circuit, zoom lens and electro-optical imaging array cooperating to generate an image from said imaging array meeting said field of view, resolution, or image interpretability rating objectives without regard to said changes in altitude or attitude of said reconnaissance vehicle,
• whereby said image having said field of view, resolution, or ground-resolvable distance objectives may be obtained without real-time operator involvement either on-board said reconnaissance vehicle or through an up-link to said reconnaissance vehicle.

A method for imaging a scene of interest with an aerial reconnaissance camera system installed in an aircraft, said system comprising a camera control computer having a computer memory, an imaging array and a zoom lens, comprising the steps of:

• a) storing in the camera control computer memory GRD (Ground Resolvable Distance), NIIRS (National Image Interpretability Rating Scale) or field of view objectives for imagery of the scene of interest;
• b) deriving information as to the aircraft height and position relative to the scene of interest;
• c) calculating a focal length setting for a zoom lens for the array to meet the GRD, NIIRS or field of view objectives for imagery of the scene from information as to the aircraft's position relative to the scene obtained in step b) and the imagery objectives for said scene;
• d) adjusting the focal length of the zoom lens in accordance with the calculations made in step c);
• and
• (e) exposing the array to the scene to generate an image of the scene of interest, whereby the image meets the objectives for the imagery.