两步域自适应少样本SAR图像车辆目标识别

    Target Recognition of Few-sample SAR Images Based on Two-step Domain Adaptation

    • 摘要: 卷积神经网络(CNN)以其优异性能在图像识别领域获得了广泛运用,但在合成孔径雷达(SAR)图像地面车辆目标识别问题上,由于在训练阶段缺乏大型实测数据集,CNN模型容易出现过拟合现象。目前,基于目标散射特性的电磁仿真SAR图像虽然相对容易获得,但仿真图像与实测图像之间存在显著域差异,直接使用仿真图像训练会出现域漂移现象,进而严重影响识别性能。针对这一问题,文中提出一种使用电磁仿真SAR图像辅助训练的算法,通过风格迁移拉近仿真图像与真实图像的视觉差异,通过对抗学习实现特征对齐,从图像的像素和特征两个层次分步实现域自适应,使特征提取网络能够提取二者之间的共性目标分类特征。在SAR典型车辆目标数据集上的实验结果表明,当参与训练的实测数据与仿真数据比例达到3∶10时,所提方法的识别准确率可达到95%左右,优于经典的域自适应算法,有效提升了SAR目标识别模型的泛化能力。

       

      Abstract: Convolutional neural networks (CNNs) have achieved widespread applications in image recognition domain due to their superior performances. However, in the context of synthetic aperture radar (SAR) image-based ground vehicle target recognition, CNN models are prone to overfitting during the training phases due to the lacks of large-scale real-measured datasets. While SAR images based on target scattering characteristics, obtained through electromagnetic simulation, are relatively easier to acquire, there exists a significant domain discrepancies between simulated and real-measured images, therefore, directly using simulated images for training leads to domain shifts, which severely impacts recognition performances. To address this issue, an algorithm that utilizes electromagnetic simulation SAR images for auxiliary training is proposed in this paper. The approach employs style transfer to reduce the visual differences between simulated and real images and achieve feature alignment through adversarial learning. Domain adaptation is implemented progressively at both the image pixel and feature levels, enabling the feature extraction network to capture common target classification features from both domains. Experimental results on a typical SAR vehicle target dataset demonstrate that when the ratio of real-measured to simulated training data reaches 3 ∶ 10, the recognition accuracy of the proposed method achieves approximately 95%, outperforming classical domain adaptation algorithms and significantly enhancing the generalization capabilities of SAR target recognition models.

       

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