arXiv:2510.11305cs.CVphysics.geo-ph2025-10被引 2

系统评估雷达洪水制图中预处理与参数调优的影响,提升水深估算精度。

Evaluating the effects of preprocessing, method selection, and hyperparameter tuning on SAR-based flood mapping and water depth estimation

  • 综合评估去噪、映射和水深估算方法及其超参数影响
  • 不同滤波器导致洪泛区范围差异达数平方公里
  • 推荐采用集成方法,降低流程不确定性

利用合成孔径雷达(SAR)影像评估去噪(尤其是斑点噪声抑制)、洪水制图和水深估算方法的影响。研究基于2019年和2021年法国加龙河两次洪灾事件,结合水动力模拟和实地观测作为参考数据,分析预处理、制图方法及超参数选择对结果的综合影响。结果表明,斑点滤波器的选择使洪泛区估计差异达数平方公里;监督方法整体优于无监督方法,但经过调优的无监督方法(如局部阈值或变化检测)可达到相近效果。预处理与制图步骤的累积不确定性显著影响水深场估计。研究强调应考虑完整处理流程,避免单一配置,建议采用集成方法并量化方法不确定性。洪水制图方法选择影响最大;而水深估算最关键的步骤是洪水制图输出及其方法超参数。

原文摘要 · Abstract (English)

Flood mapping and water depth estimation from Synthetic Aperture Radar (SAR) imagery are crucial for calibrating and validating hydraulic models. This study uses SAR imagery to evaluate various preprocessing (especially speckle noise reduction), flood mapping, and water depth estimation methods. The impact of the choice of method at different steps and its hyperparameters is studied by considering an ensemble of preprocessed images, flood maps, and water depth fields. The evaluation is conducted for two flood events on the Garonne River (France) in 2019 and 2021, using hydrodynamic simulations and in-situ observations as reference data. Results show that the choice of speckle filter alters flood extent estimations with variations of several square kilometers. Furthermore, the selection and tuning of flood mapping methods also affect performance. While supervised methods outperformed unsupervised ones, tuned unsupervised approaches (such as local thresholding or change detection) can achieve comparable results. The compounded uncertainty from preprocessing and flood mapping steps also introduces high variability in the water depth field estimates. This study highlights the importance of considering the entire processing pipeline, encompassing preprocessing, flood mapping, and water depth estimation methods and their associated hyperparameters. Rather than relying on a single configuration, adopting an ensemble approach and accounting for methodological uncertainty should be privileged. For flood mapping, the method choice has the most influence. For water depth estimation, the most influential processing step was the flood map input resulting from the flood mapping step and the hyperparameters of the methods.

洪水制图雷达遥感水深估算不确定性

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