FoBa: A Foreground-Background Co-Guided Method and New Benchmark for Remote Sensing Semantic Change Detection

Despite the remarkable progress achieved in remote sensing (RS) semantic change detection (SCD), two major challenges remain. At the data level, existing SCD datasets suffer from limited change categories, insufficient change types, and a lack of fine-grained class definitions, making them inadequate to fully support practical applications. At the methodological level, most current approaches underutilize change information, typically treating it as a postprocessing step to enhance spatial consistency, which constrains further improvements in model performance. To address these issues, we construct a new benchmark for RS SCD, LevirSCD. Focused on Beijing area, the dataset covers 16 change categories and 210 specific change types, with more fine-grained class definitions (e.g., roads are divided into unpaved and paved roads). Furthermore, we propose a foreground-background co-guided SCD (FoBa) method, which leverages foregrounds that focus on regions of interest and backgrounds enriched with contextual information to guide the model collaboratively, thereby alleviating semantic ambiguity while enhancing its ability to detect subtle changes. Considering the requirements of bitemporal interaction and spatial consistency in SCD, we introduce a gated interaction fusion (GIF) module along with a simple consistency loss to further enhance the model's detection performance. Extensive experiments on three datasets (SECOND, JL1, and the proposed LevirSCD) demonstrate that FoBa achieves competitive results compared to current state-of-the-art (SOTA) methods, with improvements of 1.48%, 3.61%, and 2.81% in the separated kappa (SeK) metric, respectively. Our code and dataset are available at https://github.com/zmoka-zht/FoBa.