Calibration And Dim Small Target Detection Of Infrared Camera Array

Infrared imaging technology can detect the infrared radiation emitted by objects and has the advantage of passive detection throughout the day.It has been widely used in target detection and other fields.The existing detection system usually adopts the single camera imaging system.In order to improve the target detection performance,the infrared camera needs to adopt large aperture to obtain higher signal-to-noise ratio and resolution.However,the increase of the aperture will increase the volume,weight and cost of the camera.At the same time,the aperture of the camera in some application scenarios has approached the limit of the current physical manufacturing process,and it is difficult to make a fundamental breakthrough in performance,so it is urgent to find new solutions.The camera array has significant advantages by synthesizing multiple small aperture cameras to equivalent the imaging performance of large aperture cameras,so as to reduce the cost of system volume,weight and cost,and even break through the performance limit of traditional single camera imaging.However,the use of infrared camera array for dim and small target detection also faces technical challenges,mainly including the high-precision array calibration required for image synthesis processing of the camera array,and the detection of dim and small targets by the camera array requires the joint detection of array sub-cameras.Aiming at the above technical challenges of infrared camera array detection of dim and small targets,the main work completed in this paper is as follows:The experimental system of long wave infrared camera array is designed.The subcamera adopts the existing mature single camera.The camera array system is composed of parallel control and data acquisition software,and multi scene data acquisition experiments are carried out to provide the basis for subsequent research.The camera imaging geometric model,camera calibration object,single camera calibration principle and method are introduced.In the calibration of long-wave infrared camera array,the traditional visible light checkerboard is no longer applicable.In view of the difficulties in designing and manufacturing long-wave imaging radiation calibration boards,and the difficulty in achieving large-size calibration objects required for long-distance imaging calibration,this paper designs a circular hole array calibration board.The long-wave infrared radiation is realized by heating by the heat source,which has the advantage of being easy to manufacture larger size calibration plates.In the calibration method of long-wave infrared camera array,this paper proposes a high-precision relative calibration method for the camera array.Based on the calculation of the internal parameters of the camera,the high-precision geometric position and posture of the camera between the sub-cameras can be obtained through the conversion of the unified coordinate system.Experimental results show that the proposed method can obtain sub-pixel-level array calibration accuracy,and can support subsequent camera array synthetic aperture imaging and joint weak and small target detection.In the aspect of infrared camera array detection of dim and small targets,this paper proposes a joint detection method for dim and small targets of infrared array based on the probability estimation module.On the basis of the single-camera pre-detection results,the spatial correlation is carried out according to the calibration results of the camera array,and the multi-camera fusion detection judgment is realized,and the optimal strategy of fusion detection is deduced.The experimental results of the infrared camera array show that the method proposed in this paper can significantly reduce the false alarm rate while maintaining the detection probability.