SAR Target Recognition with Feature Fusion Based on Stacked Autoencoder
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摘要: 该文提出了一种基于栈式自编码器(Stacked AutoEncoder, SAE)特征融合的合成孔径雷达(Synthetic Aperture Rader, SAR)图像车辆目标识别算法。首先,该算法提取了SAR图像的25种基线特征(baseline features)和局部纹理特征(Three-Patch Local Binary Patterns, TPLBP)。然后将特征串联输入SAE网络中进行融合,采用逐层贪婪训练法对网络进行预训练。最后利用softmax分类器微调网络,提高网络融合性能。另外,该文提取了SAR图像的Gabor纹理特征,进行了不同特征之间的融合实验。结果表明基线特征与TPLBP特征冗余性小,互补性好,融合后的特征区分性大。与直接利用SAE, CNN (Convolutional Neural Network)进行目标识别的算法相比,基于SAE的特征融合算法简化了网络结构,提高了识别精度与识别效率。基于MSTAR数据集的10类目标分类精度达95.88%,验证了算法的有效性。Abstract: A feature fusion algorithm based on a Stacked AutoEncoder (SAE) for Synthetic Aperture Rader (SAR) imagery is proposed in this paper. Firstly, 25 baseline features and Three-Patch Local Binary Patterns (TPLBP) features are extracted. Then, the features are combined in series and fed into the SAE network, which is trained by a greedy layer-wise method. Finally, the softmax classifier is employed to fine tune the SAE network for better fusion performance. Additionally, the Gabor texture features of SAR images are extracted, and the fusion experiments between different features are carried out. The results show that the baseline features and TPLBP features have low redundancy and high complementarity, which makes the fused feature more discriminative. Compared with the SAR target recognition algorithm based on SAE or CNN (Convolutional Neural Network), the proposed method simplifies the network structure and increases the recognition accuracy and efficiency. 10-classes SAR targets based on an MSTAR dataset got a classification accuracy up to 95.88%, which verifies the effectiveness of the presented algorithm.
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表 1 基线特征
Table 1. The selected baseline features
序号 特征 序号 特征 1 连通区域数 14 极值 2 面积 15 等圆直径 3 质心 16 充实度 4 边界矩形 17 扩展度 5 主轴长 18 周长 6 短轴长 19 重心 7 离心率 20 平均密度 8 方向 21 最小密度 9 凸多边形 22 最大密度 10 凸多边形数 23 子阵列索引 11 凸多边形面积 24 像素索引 12 填充面积 25 像素坐标 13 欧拉数 表 2 10类目标训练、测试样本数
Table 2. Number of training samples and test samples
Targets 17° 15° BMP2 233 196 BTR70 233 196 T72 232 196 BTR60 256 195 2S1 299 274 BRDM2 298 274 D7 299 274 T62 299 273 ZIL131 299 274 ZSU234 299 274 总计 2747 2426 表 3 特征分类结果
Table 3. Classification accuracy of features
目标类别 基线特征 TPLBP特征 融合后特征 BMP2 69.90 72.96 89.80 BTR70 82.14 73.98 91.33 T72 87.76 81.63 93.37 BTR60 83.59 71.79 91.79 2S1 98.54 97.08 98.54 BRDM2 83.58 99.27 96.72 D7 94.89 97.08 99.27 T62 94.87 96.70 97.07 ZIL131 98.91 99.27 99.64 ZSU234 97.08 96.72 96.35 平均精度(%) 90.19 90.40 95.88 表 4 不同特征融合分类结果
Table 4. Classification accuracy of different features
目标类别 基线+Gabor Gabor+TPLBP 基线+TPLBP BMP2 85.20 83.16 89.80 BTR70 89.29 92.35 91.33 T72 96.94 96.43 93.37 BTR60 92.82 94.36 91.79 2S1 86.13 70.44 98.54 BRDM2 97.81 98.91 96.72 D7 90.11 93.43 99.27 T62 98.91 91.94 97.07 ZIL131 98.91 98.91 99.64 ZSU234 98.54 99.64 96.35 平均精度(%) 93.65 92.00 95.88 表 5 不同算法识别精度对比
Table 5. Classification accuracy comparison of different algorithms
表 6 不同算法训练时间与测试时间对比
Table 6. Training time and testing time of different methods
算法 训练时间(s) 测试时间(s) SAE 907.5 0.154 本文算法 114.1 0.017 -
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