GFANet: An Efficient and Accurate Water Segmentation Network

Accurate water body detection is essential for autonomous navigation and operational planning of unmanned surface vehicles (USVs). To address model adaptability to ambiguous boundaries caused by diverse scenarios and climatic conditions, this study proposes GFANet (Global–Local Feature Attention Network) for the real-time water surface semantic segmentation of camera-captured images. First, a Global–Local Feature (GLF) extraction module is proposed, integrating a self-attention-based local feature extractor and a multi-scale global feature extractor for parallel feature learning, thereby enhancing hierarchical feature representation. Second, a Gated Attention (GA) module is designed with a dual-branch gating mechanism to implement noise suppression and efficient low-level feature utilization. The method was validated on three publicly available datasets in relevant domains. The experimental results on the Riwa dataset show that GFANet achieves state-of-the-art segmentation performance (4.41 M parameters, 7.15 GFLOPs) with an mIoU of 82.29% and an mPA of 89.49%. Comparable performance metrics were obtained on the USVInland and WaterSeg datasets. Additionally, GFANet achieves a 154.98 FPS processing speed, meeting real-time segmentation requirements. The experimental results verify that GFANet achieves an optimal balance between high segmentation accuracy and real-time processing efficiency.