Cropland intensity extraction combined using optical and SAR time-series in cloudy and rainy areas of southern China

doi:10.11947/j.AGCS.2024.20230497

Abstract

Abstract:

Timely and accurate acquisition of spatiotemporal distribution information regarding cropping intensity holds significant reference value for adjusting agricultural production layout and making grain production decisions. Current research on cropping intensity extraction primarily relies on optical data and phenological knowledge. However, critical phenological parameters for multi-season cropping cropland are often missing in cloudy and rainy regions of the South China, and confusable vegetation with phenological characteristics similar to crops is difficult to cull, and the salt-and-pepper noise is obvious in the pixel-level results. This paper introduces a novel method for extracting cropping intensity by integrating optical phenological parameters, SAR temporal features, and superpixel optimization based on time-series optical and SAR data. Initially, optical NDVI and LSWI temporal curves are utilized to acquire the number and duration of growth periods. Subsequently, SAR temporal features are employed to identify early-season signals of transplanting and irrigation. Finally, spatial contextual information is utilized for superpixel optimization of the cropping intensity extraction results. The effectiveness of the proposed method is validated using time-series Sentinel-1/2 data from Honghu city in 2020—2021, yielding an overall accuracy of 92.02% and a Kappa coefficient of 0.84. Results indicate that incorporating growth period duration effectively mitigates the influence of mixed vegetation, SAR temporal features accurately classify double-season rice, and superpixel optimization enhances the accuracy and completeness of planting intensity results. This method proves capable of accurately capturing cropping intensity distribution in regions with cloudy and rainy complex cropping pattern.

Key words: time-series optical, time-series SAR, cropping intensity, phenological parameters

CLC Number:

P237

Qihao CHEN, Guangchao LI, Wenjing CAO, Xiuguo LIU. Cropland intensity extraction combined using optical and SAR time-series in cloudy and rainy areas of southern China[J]. Acta Geodaetica et Cartographica Sinica, 2024, 53(12): 2361-2374.

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方案名	试验设计
方案1	生长期数量提取
方案2	生长期数量提取+生长期长度筛选
方案3	生长期数量提取+生长期长度筛选+SAR时序特征RI判别
本文方法	生长期数量提取+生长期长度筛选+SAR时序特征RI判别+SNIC超像素优化

方案	单季_PA/（%）	单季_UA/（%）	双季_PA/（%）	双季_UA/（%）	三季_PA/（%）	三季_UA/（%）	OA/（%）	Kappa
方案1	96.40	63.77	67.82	97.72	73.93	99.79	77.76	0.60
方案2	98.77	63.89	69.81	97.72	75.33	99.79	79.88	0.63
方案3	93.74	83.92	90.41	95.43	77.44	99.63	91.14	0.82
本文方法	94.07	85.66	91.59	95.70	78.30	99.90	92.02	0.84

方案	单季_PA/（%）	单季_UA/（%）	双季_PA/（%）	双季_UA/（%）	OA/（%）	Kappa
方案1	96.66	50.11	72.73	99.52	77.58	0.51
方案2	96.66	50.15	74.91	99.54	79.31	0.53
方案3	92.06	79.91	93.61	98.37	93.30	0.81
本文方法	94.50	83.90	95.10	98.97	94.98	0.85