Second, nonlinear detectors based on fractal characters were proposed, but the single detection feature fails to make full use of the return information. First, some modified adaptive detectors were proposed, such as sub-band adaptive detectors. To find small fluctuating targets in sea clutter, some new detectors have been designed. So, the detection performance of the above method for the fluctuating characteristics of multi-targets under a low SCR will drop drastically. Because the above methods are usually used in a single frame target detection, the SCR of the fluctuating characteristics target is unstable and can easily be submerged in the clutter. Therefore, the research into the flickering characteristics of multi-target detection methods under a low signal-to-clutter ratio (SCR) is of prime importance. This significantly increases the risk of shipping accidents. Owing to the discontinuous scattering of targets, the joint integration result of multiple frames cannot exceed the detection threshold, leading to missed detection.
These targets cannot be effectively detected by navigation radars in some frames.
With the influence of varying wind, waves, and sea conditions, the sea clutter appears as a sea spike, which may cause targets to display flickering characteristics in radar images. The detection of targets with smaller volumes and weaker reflections has become a new challenge, such as ice floes, buoys, and small boats. Local variance weighted information entropy (VWIE) has been applied to detect targets from SAR images and proved to be a simple and effective method for relatively complex background detection tasks. utilized a multi-scale window to calculate multi-scale local contrast measure (LCM), measuring the difference between the target area and its surrounding area, which is effective in dealing with small targets in a complex background. adopted a CFAR algorithm to detect targets with a threshold determined by the pixels’ amplitudes in background windows. introduced a bilateral CFAR algorithm for ship detection, which reduces the influence of synthetic aperture radar (SAR) ambiguities and sea clutter. They can be divided into three classes: statistic characteristic-based models represented by a constant false alarm rate (CFAR), image processing-based methods such as image enhancement by visual saliency, and artificial intelligence-based models such as intelligent networks with training data. At present, river and sea surface target detection algorithm research has received widespread attention. Thus, marine navigation radars need to be equipped with robust target detection capability. Marine navigation radar provides a full-time safe shipping guide to obviate navigation risks in oceans and rivers. With the advent of global economic integration, shipping has become the mainstay of the international transportation industry, displaying a considerable throughput. Simulation and experimental results are given to validate the assertion that the detection performance of the proposed method is greatly improved under a low SCR of 3-8 dB for multiple flickering target detection. Finally, a two-stage threshold criterion is utilized to detect the target at different amplitude levels accurately.
Fo4 flickery reflections update#
The progressive loop integral is utilized to update the target states to optimize the candidate target set. Meanwhile, updating the formula of the memory weight merit function can strengthen the joint frame correlation of the flickering characteristics target. Firstly, a global detection operator is used to discretize the multi-target state into multiple single-target states, achieving the discretization of numerous targets. A biological memory model-based dynamic programming multi-target joint detection method was proposed to address this issue in this paper. This phenomenon causes a severe decline in the detection performance of traditional detection methods. Moreover, the targets exhibiting stronger fluctuation disappear in some frames of the radar images, which is known as flickering characteristics. However, time-varying river and sea surfaces will induce target scattering changes, known as fluctuating characteristics. The robust target detection ability of marine navigation radars is essential for safe shipping.
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