A Flexible Hybrid Attention Mechanism for Multi-Architecture Segmentation of Small Maritime Targets in South East Region of Iran

Maritime vessel detection in satellite imagery is essential for coastal monitoring, traffic regulation, and maritime security. Vessels along the southeastern coast of Iran exhibit unique structural and geometric characteristics; they are small and overlapped, differing substantially from international benchmarks. Detecting small and overlapping vessels presents additional challenges due to the loss of fine-grained features and ambiguous object boundaries in conventional deep learning pipelines. Consequently, existing pre-trained models, trained primarily on global datasets, often fail to generalize effectively to this region. To address this, in our study, we provide the first systematic investigation of ship detection for southeastern Iran, supported by a curated dataset of high-resolution satellite imagery from its major ports. We, then, propose a flexible Hybrid Attention Fusion (HAF) module that can be seamlessly integrated into multiple segmentation architectures, including FPN, Mask R-CNN, U-Net, and DeepLab. The module sequentially applies channel and spatial attention mechanisms to adaptively recalibrate multi-scale features, enhancing the representation of subtle and occluded instances. Experimental results demonstrate that HAF-augmented models significantly outperform their baseline counterparts across all architectures. For semantic segmentation, U-Net+HAF and DeepLabv۳+HAF achieve mean IoU improvements of ۴.۵% and ۴.۴%, respectively, reaching ۸۳.۸% and ۸۵.۵% mIoU. For instance segmentation, Mask R-CNN+HAF demonstrates the most substantial improvement in small object detection, with Average Precision for small objects (APs) increasing from ۴۲.۳% to ۵۰.۶%—an ۸.۳-point improvement. Qualitative analysis confirms superior capability in detecting missed small instances, separating overlapping vessels, and producing more precise boundaries compared to baseline models.

کلیدواژه ها:

Satellite images ، ship detection and segmentation ، deep learning ، South East Iran ، Attention Mechanism