Offshore and inland river ship detection has been studied on both synthetic aperture radar (SAR) and optical remote sensing imagery. However, the classic ship detection methods based on SAR images can cause a high false alarm ratio and be influenced by the sea surface model, especially on inland rivers and in offshore areas. The classic detection methods based on optical images do not perform well on small and gathering ships. This paper adopts the idea of deep networks and presents a fast regional-based convolutional neural network (R-CNN) method to detect ships from high-resolution remote sensing imagery. First, we choose GaoFen-2 optical remote sensing images with a resolution of 1 m and preprocess the images with a support vector machine (SVM) to divide the large detection area into small regions of interest (ROI) that may contain ships. Then, we apply ship detection algorithms based on a region-based convolutional neural network (R-CNN) on ROI images. To improve the detection result of small and gathering ships, we adopt an effective target detection framework, Faster-RCNN, and improve the structure of its original convolutional neural network (CNN), VGG16, by using multiresolution convolutional features and performing ROI pooling on a larger feature map in a region proposal network (RPN). Finally, we compare the most effective classic ship detection method, the deformable part model (DPM), another two widely used target detection frameworks, the single shot multibox detector (SSD) and YOLOv2, the original VGG16-based Faster-RCNN, and our improved Faster-RCNN. Experimental results show that our improved Faster-RCNN method achieves a higher recall and accuracy for small ships and gathering ships. Therefore, it provides a very effective method for offshore and inland river ship detection based on high-resolution remote sensing imagery.
Aiming at intelligent decision-making of UAV based on situation information in air combat, a novel maneuvering decision method based on deep reinforcement learning is proposed in this paper. The autonomous maneuvering model of UAV is established by Markov Decision Process. The Twin Delayed Deep Deterministic Policy Gradient(TD3) algorithm and the Deep Deterministic Policy Gradient (DDPG) algorithm in deep reinforcement learning are used to train the model, and the experimental results of the two algorithms are analyzed and compared. The simulation experiment results show that compared with the DDPG algorithm, the TD3 algorithm has stronger decision-making performance and faster convergence speed, and is more suitable forsolving combat problems. The algorithm proposed in this paper enables UAVs to autonomously make maneuvering decisions based on situation information such as position, speed, and relative azimuth, adjust their actions to approach and successfully strike the enemy, providing a new method for UAVs to make intelligent maneuvering decisions during air combat.
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