GAUDI: Geometry-Aware Diffusion for Calibrated Air-Quality Time-Series Imputation
This study addresses the failure of side information in imputing continuous block missingness in air quality sensor data by proposing a geometry-aware conditional diffusion model. Through joint conditioning on masks and observed values alongside variable identity encoding, the model preserves temporal characteristics while mitigating interference from absolute positional embeddings. Furthermore, a block-missing-specific configuration is designed to effectively isolate the geometry-aware conditioning effects, thereby enhancing robustness. Evaluated on the ItalyAir dataset, the proposed method achieves an RMSE of 0.340, significantly outperforming both full-context and CSDI baselines. This work establishes an efficient imputation paradigm for scenarios involving long continuous missing segments.