A Method of Measuring Aircraft Height from the Ground Based on Image Matching

Abstract

The invention provides an image-matching-based method for measuring the height of an aircraft from the ground, using a camera visual sensor to acquire three real-time ground scene images from different angles, performing real-time image feature matching, and completing the measurement of the height of the aircraft from the ground according to the matching results. The altitude measurement of the aircraft is completed only by acquiring three real-time images of different positions, and does not require additional information such as the focal length of the camera, which reduces the demand for equipment and is applicable to a wide range of platforms. Through real-time image matching, there is no need to know what information is contained in the image in advance, and the environment applicability is better. Through the design of shooting tilt angle, the requirements for real-time images are reduced, and it also has better performance in dynamic environments.

Description

technical field [0001] The invention relates to the field of photoelectric distance measurement, uses a visual sensor to measure the height of an aircraft from the ground, is used for measuring the height of an aircraft such as an unmanned aerial vehicle, and can also provide technical reference for distance measurement of other visual platforms. Background technique [0002] Accurate measurement of aircraft altitude is crucial to flight control, and the commonly used altimeter is radar altimeter. The radar altimeter has a large volume and is easily affected by ground stray waves or radio interference, resulting in a decrease in accuracy, and it needs to continuously transmit radio waves to the ground, which is not conducive to the concealment of the aircraft itself. Therefore, it is necessary to find a simple, reliable, autonomous, and anti-jamming high-precision altimetry and ranging method. [0003] Visual distance measurement is to use a video camera or camera to captur...

AI Technical Summary

Problems solved by technology

The paper "Su Ang. Research on Altimetry and Attitude Measurement by Scene Matching of Aircraft [D], Changsha: National University of Defense Technology, 2011." proposed two altimetry methods based on scene matching, one is single-frame multi-point matching altimetry , this method of altimetry needs to match the captured real-time map with the reference map. In fact, the shooting time of the real-time map and the reference map may be far away, resulting in a large change in the imaging scene, and due to the influence of the attitude of the aircraft, the real-time map There are bound to be geometric distortions during imaging, and there are many error sources for height measurement, so the final measurement accuracy is not high; the other is inter-frame matching height measurement. This method does not need to match the real-time image and the reference image, and only needs two real-time images. Match the center point of the real-time image of the previous frame with the current frame to find its corresponding image coordinates on the real-time image of the current frame, and use the ratio of the image coordinate displacement of the center point of the real-time image to the ground coordinate displacement to obtain the current aircraft height, causing height measurement The errors mainly include the ground horizontal coordinate displacement error of the center point of the real-time map, the image coordinate displacement error, the equivalent focal length error of the camera, and the attitude angle error, etc. These error sources need to be calibrated when used across platforms, and the application occasions will be limited

Images