A robust approach for large-scale cropping intensity mapping in smallholder farms from vegetation, brownness indices and SAR time series

•Cropping cycles were depicted based on dynamic patterns of vegetation and brownness indices.•The CI mapping algorithm was efficient in reducing the omission errors of double rice.•The first 10-m CI map over conterminous China was generated using Sentinel-1/2 data.•Around 28% of cropped fields are cultivated by multiple cropping in China in 2020.