A Global Model Approach to Robust Few-Shot SAR Automatic Target Recognition
This addresses the challenge of limited labeled data for SAR target recognition in real-world scenarios, offering a more flexible and extendable approach compared to existing methods.
The paper tackles the few-shot SAR Automatic Target Recognition problem by training a global representation model via self-supervised learning on unlabeled data and using it as a feature extractor, achieving high accuracy and robust out-of-distribution detection in various few-shot settings.
In real-world scenarios, it may not always be possible to collect hundreds of labeled samples per class for training deep learning-based SAR Automatic Target Recognition (ATR) models. This work specifically tackles the few-shot SAR ATR problem, where only a handful of labeled samples may be available to support the task of interest. Our approach is composed of two stages. In the first, a global representation model is trained via self-supervised learning on a large pool of diverse and unlabeled SAR data. In the second stage, the global model is used as a fixed feature extractor and a classifier is trained to partition the feature space given the few-shot support samples, while simultaneously being calibrated to detect anomalous inputs. Unlike competing approaches which require a pristine labeled dataset for pretraining via meta-learning, our approach learns highly transferable features from unlabeled data that have little-to-no relation to the downstream task. We evaluate our method in standard and extended MSTAR operating conditions and find it to achieve high accuracy and robust out-of-distribution detection in many different few-shot settings. Our results are particularly significant because they show the merit of a global model approach to SAR ATR, which makes minimal assumptions, and provides many axes for extendability.