基于混合监督对比学习的小样本多视角SAR目标识别

    Hybrid Supervised Contrastive Learning for Few-shot Multi-view SAR Target Recogniton

    • 摘要: 标记样本不足与视角多样性是制约合成孔径雷达(SAR)目标识别性能的关键难点。针对这一问题,文中提出了一种面向小样本多视角SAR图像识别的混合监督对比学习框架。该方法将训练流程划分为上游表征学习阶段与下游分类器学习阶段,并引入多视角特征融合策略以挖掘不同视角下的互补信息。在上游阶段,通过对SAR图像切片进行多种随机增强操作,扩展了有效批次规模并构建多样化的正负样本对,将增强样本输入共享的多视角融合网络与投影头,映射至对比空间,再由混合监督对比模块联合实施无监督实例判别与监督类别判别,提升特征空间的判别性与类内紧凑性。在下游阶段,移除投影头,仅训练线性分类器,以完成最终识别任务。在小样本公开的运动和静止目标获取与识别数据集上的实验结果表明,所提方法在小样本与多视角SAR识别场景中具备显著优势,优于传统监督学习方法及传统无监督学习方法,表现出良好的识别精度与泛化能力,验证了所提模型的有效性与应用潜力。

       

      Abstract: Insufficient labeled samples and diverse viewing angles are two major challenges that constrain the performance of synthetic aperture radar (SAR) target recognition. To address these issues, a hybrid supervised contrastive learning framework tailored for few-shot multi-view SAR image recognition is proposed. The proposed method divides a training process into two stages: an upstream representation learning stage and a downstream classifier learning stage, incorporating a multi-view feature fusion strategy to exploit complementary information across different viewing angles. In the upstream stage, various random augmentation operations are applied to SAR image patches to enlarge the effective batch size and construct diverse positive and negative sample pairs. These augmented samples are fed into a shared multi-view fusion network and a projection head, which maps the features into a contrastive space. A hybrid supervised contrastive module then jointly performs unsupervised instance discrimination and supervised label discrimination, improving both the discriminability of the feature space and the intra-class compactness. In the downstream stage, the projection head is removed, only a linear classifier is trained to perform the final recognition task. Experimental results on the few-shot moving and stationary target acquisition and recognition dataset demonstrate that the proposed method achieves significant improvements in recognition accuracy and generalization ability over conventional supervised and some unsupervised learning methods. These results validate the effectiveness and application potential of the proposed model in few-shot multi-view SAR recognition scenarios.

       

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