SAR ATR Based on FCNN and ICAE
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摘要: 近年来,基于卷积神经网络(Convolutional Neural Network, CNN)的合成孔径雷达(Synthetic Aperture Radar, SAR)图像目标识别得到深入研究。全卷积神经网络(Fully Convolutional Neural Network, FCNN)是CNN结构上的改进,它比CNN能获得更高的识别率,但在训练过程中仍需要大量的带标签训练样本。该文提出一种基于FCNN和改进的卷积自编码器(Improved Convolutional Auto-Encoder, ICAE)的SAR图像目标识别方法,即先用ICAE无监督训练方式获得的编码器网络参数初始化FCNN的部分参数,后用带标签训练样本对FCNN进行训练。基于MSTAR数据集的十类目标分类实验结果表明,在不扩充带标签训练样本的情况下,该方法不仅能获得98.14%的平均正确识别率,而且具有较强的抗噪声能力。Abstract: In recent years, Synthetic Aperture Radar (SAR) image target recognition based on the Convolutional Neural Network (CNN) has attracted a significant amount of attention. Fully CNN (FCNN) is a structural improvement of the CNN, which features a higher recognition rate than CNN, but it still requires a large number of labeled data in the training process. This study aims to propose a method of SAR image target recognition based on FCNN and Improved Convolutional Auto-Encoder (ICAE), where several parameters of FCNN are initialized by the parameters of the ICAE encoder. These parameters are obtained in the unsupervised training mode. Then, the FCNN is trained by the labeled training samples. The experimental results on 10 kinds of target classification based on the MSTAR datasets show that this method cannot only achieve an average of 98.14% correct recognition rate but also feature a strong anti-noise capability when the labeled training samples are unexpanded.
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表 1 训练样本和测试样本数量
Table 1. The number of training and testing images
型号 训练集 测试集 角度 数量 角度 数量 BMP-2 17° 233 15° 195 BTR-70 17° 233 15° 196 BTR-60 17° 256 15° 195 BRDM-2 17° 298 15° 274 T-72 17° 232 15° 196 T-62 17° 299 15° 273 2S1 17° 299 15° 274 D7 17° 299 15° 274 ZIL-131 17° 299 15° 274 ZSU-234 17° 299 15° 274 表 2 FCNN, ICAE, CNN和CAE的网络结构
Table 2. The network structures of FCNN, ICAE, CNN and CAE
FCNN ICAE CNN CAE Conv.16@3×3
Conv.16@3×3/stride=2Conv.16@3×3
Conv.16@3×3/stride=2Conv.16@3×3
Maxpooling@2×2Conv.16@3×3
Maxpooling@2×2Conv.32@3×3
Conv.32@3×3/stride=2Conv.32@3×3
Conv.32@3×3/stride=2Conv.32@3×3
Maxpooling@2×2Conv.32@3×3
Maxpooling@2×2Conv.64@3×3
Conv.64@3×3/stride=2Conv.64@3×3
Conv.64@3×3/stride=2Conv.64@3×3
Maxpooling@2×2Conv.64@3×3
Maxpooling@2×2Conv.128@3×3
Conv.128@3×3/stride=2Conv.128@3×3
Conv.128@3×3/stride=2Conv.128@3×3
Maxpooling@2×2Conv.128@3×3
Maxpooling@2×2Conv.10@4×4
SoftmaxUnpooling@2×2
Deconv.64@3×3Conv.10@4×4
SoftmaxUnpooling@2×2
Deconv.64@3×3Unpooling@2×2
Deconv.32@3×3Unpooling@2×2
Deconv.32@3×3Unpooling@2×2
Deconv.16@3×3Unpooling@2×2
Deconv.16@3×3Deconv.1@3×3 Deconv.1@3×3 表 3 基于FCNN和ICAE的识别结果
Table 3. The recognition results based on FCNN and ICAE
目标型号 识别结果 正确识别率
(%)2S1 BMP-2 BRDM-2 BTR-60 BTR-70 D7 T-62 T-72 ZIL-131 ZSU-234 2S1 265 0 1 0 2 0 0 6 0 0 96.72 BMP-2 1 191 0 0 1 1 0 1 0 0 98.45 BRDM-2 0 0 270 3 0 0 0 0 1 0 98.54 BTR-60 0 0 2 186 0 0 1 0 2 4 95.38 BTR-70 3 0 0 0 193 0 0 0 0 0 98.47 D7 0 0 2 0 0 272 0 0 0 0 99.27 T-62 0 0 0 0 0 0 270 0 0 3 98.90 T-72 0 1 0 0 1 0 0 194 0 0 98.98 ZIL-131 0 0 0 0 0 1 2 0 270 1 98.54 ZSU-234 0 0 0 0 0 3 1 1 0 269 98.18 平均正确识别率(%) 98.14 表 4 基于不同方法的实验结果对比
Table 4. The comparison of experimental results based on different methods
目标型号 识别率(%) FCNN+ICAE CNN+CAE FCNN CNN 2S1 96.72 95.99 94.16 96.72 BMP-2 97.95 97.44 96.41 94.36 BRDM-2 98.54 95.99 96.35 95.26 BTR-60 95.38 91.79 95.38 96.41 BTR-70 98.47 99.49 98.98 93.88 D7 99.27 96.35 98.54 97.81 T-62 98.90 97.07 90.84 93.41 T-72 98.98 98.98 98.47 97.96 ZIL-131 98.54 98.91 97.81 96.35 ZSU-234 98.18 98.91 99.64 94.89 平均正确识别率(%) 98.14 97.11 96.58 95.71 -
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