Ship target detecting and discriminating method in SAR image with complicated background

Abstract

The invention belongs to the technical field of radar image processing, and particularly relates to a ship target detecting and discriminating method in an SAR image with a complicated background. The method comprises the following main steps of (1), fine sea-and-land dividing; (2), performing high-efficiency detection on the ship target, wherein the step comprises large-scale CFAR and small-scale iteration CFAR, wherein a synthetic aperture radar image clutter statistics distribution model based on generalized Gamma distribution is used; and (3), performing nearshore target false alarm discrimination, wherein the step comprises a false alarm discriminating algorithm based on a maximal likelihood and a false alarm discriminating algorithm based on polarization information. The method can efficiently and accurately detect the ship target in complicated backgrounds such as nearshore and harbor, and furthermore can utilize the false alarm discriminating algorithm based on maximal likelihood and the polarization information for discriminating a false alarm target, thereby improving ship target detecting accuracy. The ship detecting algorithm provided by the invention is suitable for a random SAR image background and furthermore has advantages of high robustness, high real-time performance and good popularization prospect.

Description

[0001] field of invention [0002] The invention belongs to the technical field of radar image processing, and in particular relates to a ship target detection and identification method in complex background SAR images. Background technique [0003] Synthetic Aperture Radar (SAR) has all-weather and all-weather earth observation capabilities. SAR has been widely used in ocean monitoring and has exerted huge social, economic and military benefits. In recent years, a large number of multi-polarization and full-polarization satellites have been successfully launched, which can effectively obtain the polarization information of ground targets, and then can identify different scattering mechanisms and scatterers through polarization information. [0004] The constant false alarm rate (Constant False Alarm Rate, CFAR) ship detection technology is one of the most commonly used SAR image target detection. CFAR uses a pixel-by-pixel sliding window for target detection. The time complex...

AI Technical Summary

Problems solved by technology

However, due to the influence of coherent speckle noise in SAR images, the influence of land distribution, and the obvious influence of land light and shade, it is difficult to adapt to various complex land and sea conditions.

[0007] At present, the false alarm identification technology mainly used in SAR image ship detection is based on information such as the area, shape, and aspect ratio of the ship. Similar to this false alarm identification technology, there are two main problems: 1) it is affected by the ship It is difficult to accurately measure the area, shape and aspect ratio of the ship due to the influence of side lobe leakage, coherent speckle noise, ship wake, image resolution, etc.; 2) There are often many artificial false alarm targets in coastal waters, and they The backscattering coefficient is relatively large and the intensity is strong, and the shape is mostly "rectangular". It is difficult to distinguish it from the ship target by this method.

Images