Research On Shadow Detection And Tracking Technology Of Video SAR Based On Tracking Before Detection

Moving target shadows appear continuously in the sequential high-resolution images produced by video synthetic aperture radar(Vi SAR).Tracking moving targets by moving target shadows in images belongs to the problem of dim target detection and tracking in complex background,and the dynamic programming-based track before detection(DP-TBD)algorithm is suitable for such problems because it can realize the incoherent accumulation of target energy.To detect and track multiple strong maneuvering targets in the video SAR image sequence,this paper proposed a joint processing strategy-based DP-TBD(JP-DPTBD)algorithm.Benefiting from both of the location and radial velocity information of the targets in the video SAR image and range-Doppler(RD)spectrum,the JP-DP-TBD algorithm can screen the state candidate region and retain more states that conform to the motion law of the target.Meanwhile,we adopt a dual-frame close-range matching mechanism to complete the automatic initialization of the candidate target state,whose validity has been verified on the real video SAR data.Experimental results on simulated data demonstrate that the proposed algorithm has better detection ability and fewer false alarms in comparison with other TBD algorithms.The JP-DP-TBD algorithm first transforms raw echo data of radar into continuous video SAR images and corresponding range Doppler(RD)spectra,then we adopt a dual-frame close-range matching mechanism to automatically extract the initial state of candidate targets,so as to integrate the whole detection process.Next,all the target states of the previous frame are transferred to form the candidate region of the next frame,and the candidate region is screened by combining the information on video SAR image data and RD spectra.The main contributions of this article can be summarized as follows.We propose a JP-DPTBD algorithm to detect and track multiple strong maneuvering target shadows in video SAR.Different from the previous methods,the JP-DP-TBD algorithm extract useful information out of the echo signal of radar,its core idea is to jointly utilize position information in the image sequence and the velocity information in the RD spectrum so as to screen the target states.Compared to the conventional DP-TBD and ES-TBD algorithms,the proposed approach exhibits better detection performance of moving targets with fewer false alarms.Moreover,Under the premise of only using video SAR image data,we also propose an initialization algorithm based on the dual-frame close-range matching mechanism to solve a primary problem of the automatic extraction of the initial state in video SAR,which contributes to a good foundation for the subsequent detection and tracking.