The Change You Want To Detect: Semantic Change Detection In Earth Observation With Hybrid Data Generationf

Bi-temporal change detection at scale based on Very High Resolution (VHR) images is crucial for Earth monitoring. Such task remains poorly addressed even in the deep learning era: it either requires large volumes of annotated data - in the semantic case - or is limited to restricted datasets for binary set-ups. Most approaches do not exhibit the versatility required for temporal and spatial adaptation: simplicity in architecture design and pretraining on realistic and comprehensive datasets. Synthetic datasets is the key solution but still fails handling complex and diverse scenes. In this paper, we present HySCDG a generative pipeline for creating a large hybrid semantic change detection dataset that contains both real VHR images and inpainted ones, along with land cover semantic map at both dates and the change map. Being semantically and spatially guided, HySCDG generates realistic images, leading to a comprehensive and hybrid transfer-proof dataset FSC-180k. We evaluate FSC-180k on five change detection cases (binary and semantic), from zero-shot to mixed and sequential training, and also under low data regime training. Experiments demonstrate that pretraining on our hybrid dataset leads to a significant performance boost, outperforming SyntheWorld, a fully synthetic dataset, in every configuration. All codes, models, and data will be made available.