VLF-SAR: A Novel Vision-Language Framework for Few-Shot SAR Target Recognition

Abstract

Due to the challenges of obtaining data from valuable targets, few-shot learning plays a critical role in synthetic aperture radar (SAR) target recognition. However, the high noise levels and complex backgrounds inherent in SAR data make this technology difficult to implement. To improve the recognition accuracy, in this paper, we propose a novel vision-language framework, VLF-SAR, with two specialized models: VLF-SAR-P for polarimetric SAR (PolSAR) data and VLF-SAR-T for traditional SAR data. Both models start with a frequency embedded module (FEM) to generate key structural features. For VLF-SAR-P, a polarimetric feature selector (PFS) is further introduced to identify the most relevant polarimetric features. Also, a novel adaptive multimodal triple attention mechanism (AMTAM) is designed to facilitate dynamic interactions between different kinds of features. For VLF-SAR-T, after FEM, a multimodal fusion attention mechanism (MFAM) is correspondingly proposed to fuse and adapt information extracted from frozen contrastive language-image pre-training (CLIP) encoders across different modalities. Extensive experiments on the OpenSARShip2.0, FUSAR-Ship, and SAR-AirCraft-1.0 datasets demonstrate the superiority of VLF-SAR over some state-of-the-art methods, offering a promising approach for few-shot SAR target recognition.