Unsupervised Domain Factorization Network for Thick Cloud Removal of Multitemporal Remotely Sensed Images

Cloud removal is an important task in remotely sensed images (RSIs) processing, which is beneficial for downstream applications, such as unmixing, fusion, and target detection. Multitemporal RSIs (MRSIs), which contains abundant spatial–spectral–temporal (SST) information, potentially bring new opportunities for cloud removal. However, how to effectively and efficiently explore the rich information of MRSIs remains a challenge. Inspired by the low-rankness of MRSIs, we propose an Unsupervised Domain Factorization Network (UnDFN) for thick cloud removal, which allows us to effectively and efficiently exploit the rich SST information of MRSIs. In the UnDFN framework, we first factorize RSI for each time node of MRSIs into its corresponding spatial factor and spectral factor. Due to powerful expressive ability, untrained neural networks (NNs) are leveraged to faithfully capture the spatial and spectral factors. Especially, motivated by the low-rankness of the concatenated spatial factors of all time nodes, a low-rank spatial factor module is elaborately designed to effectively and efficiently capture the spatial factors of all time nodes as compared with separately using networks to capture spatial factors for each time node. Extensive experiments on simulated and real MRSIs of different satellites (including Sentinel-2 and Landsat-8) substantiate that the proposed UnDFN achieves state-of-the-art performance in thick cloud removal compared to other methods.