A Novel Detector for Adaptive Detection of Weak and Small Ships in Compact Polarimetric SAR

Compact polarimetric (CP) synthetic aperture radar (SAR) is now widely used for ship detection due to its excellent balance of data acquisition and resource allocation. In this article, a novel ship detector for weak and small targets is constructed using the CP SAR data of circular transmit linear receive mode. First, based on the X-Bragg model and circular anisotropy, a new feature DB is proposed to characterize the intensity of double-bounce scattering. Then, a new detector DBHw combining double-bounce scattering intensity DB and entropy Hw is constructed to characterize the difference in scattering mechanism and scattering randomness between ship targets and the sea clutter background. An adaptive constant false alarm rate (CFAR) detection method is implemented based on this novel detector and the generalized Gamma distribution (GΓD). Finally, experiments were conducted using CP SAR data simulated from L-band UAVSAR full polarimetric data. The signal-clutter ratio (SCR) values for strong backscattering and weak backscattering ships of DBHw are 9.4613 and 9.6705, respectively, and of g0 are 16.7497 and 2.2358, respectively, demonstrating the stability and superiority of DBHw regardless of the span of targets. The detection result of DBHw is 30 out of 32, and of DB, Hw, and g0 is 19, 20, and 11 out of 32, respectively, demonstrating the significant improvement of DBHw based on DB and Hw, and the superiority of power-independent detector DBHw compared with g0 in detecting weak and small ship targets. © 2019 IEEE.