PAN: Part Attention Network Integrating Electromagnetic Characteristics for Interpretable SAR Vehicle Target Recognition

Machine learning methods for synthetic aperture radar (SAR) image automatic target recognition (ATR) can be divided into two main types: traditional methods and deep learning methods. The deep learning methods can learn the high-dimensional features of the target directly and usually obtain high target recognition accuracy. However, they lack full consideration of SAR targets' inherent characteristics, resulting in poor generalization and interpretation ability. Compared with deep learning methods, traditional methods can get more interpretable and stable results with model-based features. In order to take full advantage of these two kinds of methods, we propose the target part attention network (PAN) based on the attributed scattering center (ASC) model to integrate the electromagnetic characteristics with the deep learning framework. First, considering the importance of scattering structure for SAR ATR, we design a target part model based on the ASC model. Then, a novel part attention module based on the scaled dot-product attention mechanism is proposed, which directly associates the features of target parts with the classification results. Finally, we give the derivation method of the importance of each part, which is of great significance for practical application and the interpretation of SAR ATR. Experiments on the MSTAR dataset demonstrate the effectiveness of the proposed PAN. Compared with existing studies, it can achieve higher and more robust classification accuracy under different complex conditions. Furthermore, combined with the importance of parts, we constructed two effective interpretable analysis methods for deep learning network classification results.