Abstract: Optical remote sensing imaging is highly susceptible to clouds, which leads to partial information degradation or loss and significantly limits data availability. In contrast, synthetic aperture radar (SAR) is capable of all-weather and all-day imaging, providing stable structural information unaffected by cloud cover. To address the demand for high-quality utilization of multimodal remote sensing data in complex cloud-covered scenarios, this paper investigates an optical-SAR complementary information fusion approach for cloud removal. An attention-guided multimodal fusion framework is proposed, in which gated convolutional structures and multi-level attention mechanisms are jointly employed to enable multi-scale feature extraction and global cross-modal dependency modeling, thereby enhancing feature alignment and information interaction between optical and SAR modalities. Specifically, a cross-attention mechanism is introduced to guide SAR features in compensating for the information missing in cloud-covered optical regions. Furthermore, a multimodal cloud removal unit is designed to integrate deep features and map them back to the image space, effectively suppressing cloud artifacts while strengthening ground object representation to reconstruct cloud-free optical images. Experimental results demonstrate that the proposed method achieves notable improvements in cloud removal accuracy, detail preservation, and structural consistency compared with existing methods, and validates the effectiveness of multimodal complementary fusion for optical remote sensing image cloud removal.

Key words: optical remote sensing images, cloud removal, SAR, attention mechanism, multimodal fusion