Transformation-Invariant Network for Few-Shot Object Detection in Remote-Sensing Images

Object detection in remote-sensing images (RSIs) relies on a large amount of labeled data for training. However, the increasing number of new categories and class imbalance make exhaustive annotation impractical. Few-shot object detection (FSOD) addresses this issue by leveraging meta-learning on seen base classes and fine-tuning on novel classes with limited labeled samples. Nonetheless, the substantial scale and orientation variations of objects in RSIs pose significant challenges to existing FSOD methods. To overcome these challenges, we propose integrating a feature pyramid network (FPN) and utilizing prototype features to enhance query features, thereby improving existing FSOD methods. We refer to this modified FSOD approach as a Strong Baseline, which has demonstrated significant performance improvements compared to the original baselines. Furthermore, we tackle the issue of spatial misalignment caused by orientation variations between the query and support images by introducing a transformation-invariant network (TINet). TINet ensures geometric invariance and explicitly aligns the features of the query and support branches, resulting in additional performance gains while maintaining the same inference speed as the Strong Baseline. Extensive experiments on three widely used remote-sensing object detection datasets, that is, NWPU VHR-10.v2, DIOR, and HRRSD demonstrated the effectiveness of the proposed method.