Study On Detection Method Of Near Space Infrared Target In Space-based Platform

Near-space vehicle is a new type of aircraft, which flies in near space and completes a specific task. The detection of near-space vehicle has become one of the hotspot and difficulty in the military field. By analyzing the infrared radiation characteristics of near-space target and the environment, and combining with the sparsity of the infrared image, the detection problem of near-space infrared target in space-based platform is studied. The main work and achievements of this paper are as follows.(1) The application and difficulties of the near space targets detection in space-based platform was introduced. The detection of near space infrared target in space-based platform is equivalent to the detection of infrared dim small target because of the long detection distance, the small target and the complex environment. The research situation at home and abroad of infrared dim target detection is analyzed.(2) The imaging mechanism and characteristics of infrared image are analyzed; the infrared small target image model is established; and the characteristics of near space target, background and noise are studied. The performance evaluation index of the infrared dim target detection method, such as the signal-to-clutter ratio, the signal-to-clutter ratio gain, the background suppression factor and the ROC curve, are presented to evaluate the performance of different detection methods.(3) The basic principles and characteristics of non-subsampled shearlet transform and spectral graph wavelet transform, the new multiscale geometric analysis method, are studied. The realization principle and the theory basis of the random projection method are studied and analyzed in detail. This chapter is the theory foundation for the study of the following detection methods.(4) For the background suppression problem of near space target detection in space-based platform, an infrared dim and small target detection method based on multi-scale random projection is proposed. First, the original infrared image is decomposed by non-subsampled Pyramid. Then, the Mahalanobis distance of the high frequency subbands are calculated in the random projection domain to suppress background and enhance target simultaneously. Finally, the target is detected by using the adaptive threshold segmentation. The simulation experiment results show that the proposed method can detect effectively the near space infrared dim and small target in space-based platform and has the better background suppression ability and real-time performance.(5) For the background suppression and noise problem of near space target detection in space-based platform, a moving target detection method combined the sparse decomposition with random projection is proposed by utilizing the continuous motion and the gray stability of target in image sequences. First, the image is decomposed by the morphological component analysis method based on non-subsampled shearlet transform and spectral graph wavelet transform to separate target and background clutter. Then, the target image sequence is randomly projected to reduce the interframe redundancy. Finally, the moving trajectory of the target is obtained by using the RX filtering method. The simulation experiment results show that, the proposed method can effectively and robustly detect the near space infrared dim and small target in space-based platform.