高级检索+

基于遥感数据时空特征提取的冬小麦估产方法

Predicting winter wheat yield using spatiotemporal feature extraction from remote sensing data

  • 摘要: 冬小麦在中国粮食生产中具有重要地位,及时且准确地预测其产量对粮食安全和农业可持续发展具有重要意义。遥感为大规模作物估产提供了便利,然而,主流的基于卷积-循环混合神经网络的冬小麦估产方法难以充分学习长时序遥感影像中的全局空间光谱特征和长距离时间依赖关系。因此,该研究提出了一种面向遥感影像全局-局部时空特征提取的冬小麦估产模型。该模型采用CNN与Vision Transformer(ViT)并行的双分支架构,同时提取遥感影像的局部纹理、光谱响应等特征和全局空间光谱信息。随后,通过耦合注意力融合模块(coupled attention fusion module,CAFM),在全局与局部特征的双向交互过程中自适应整合空谱信息。最后,结合基于Transformer的时间编码器,以精准捕捉作物生长过程中的长距离时间依赖关系。该模型通过全面挖掘冬小麦生长的空间、光谱和时间动态特征,以有效提升估产的准确性。该研究以全国冬小麦主产区为研究区,基于2003—2022年的冬小麦产量数据和MODIS遥感影像,构建估产数据集并验证GSTFEN模型的性能。结果表明:1)在2019—2022年测试集中,GSTFEN模型的年平均均方根差(root mean square error,RMSE)、平均绝对误差(mean absolute error,MAE)和决定系数(coefficient of determination,R2)分别达到0.591 t/hm2、0.475 t/hm2和0.848,性能优于基线模型7%~40%。2)GSTFEN模型在播种至抽穗期生育阶段的年平均RMSE与播种至成熟阶段仅相差2.31%,表明该模型能够提前1个月预测全国冬小麦主产区产量。该研究所提方法可以有效提高大范围农作物产量预测精度,为作物生长过程智能化监测提供了方法支撑。

     

    Abstract: Winter wheat can play a crucial role in grain production in China. An accurate prediction of the grain yield is of great significance for food security in sustainable agriculture. Fortunately, remote sensing can provide an effective means for the large-scale prediction of the crop yield; However, the mainstream approaches of the convolutional–recurrent neural network cannot fully capture the global spatial–spectral features, and long-range temporal dependencies in the long-term remote sensing imagery. The generalization and spatial stability of the winter wheat yield prediction can be limited in the large and heterogeneous production regions. In this study, an accurate model was proposed to predict the winter wheat yield using global–local spatiotemporal feature extraction from the remote sensing imagery, named as the global–local spatiotemporal feature extraction network (GSTFEN). A dual-branch architecture was adopted to combine the convolutional neural networks (CNN) and vision transformers (ViT). The local texture and spectral response features were extracted for the global spatial–spectral information from the multi-temporal MODIS imagery at the county scale. A coupled attention fusion module (CAFM) was introduced to adaptively integrate the spatial–spectral information, according to the bidirectional interactions between global and local features. The complementary information was jointly exploited from the CNN and ViT modules. A temporal encoder with Transformer was further employed to capture the long-range temporal dependencies in the crop growth cycle, because the growth stages were more critical for the final yield formation. The spatial, spectral, and temporal dynamics of the winter wheat growth were determined to improve the accuracy of the yield prediction using GSTFEN. A unified framework was provided for the spatiotemporal feature learning in the prediction of the large-scale yield. The study area was taken from the major winter wheat-producing regions in China. A county-level dataset of the yield prediction was constructed to integrate the winter wheat yield data from 2003 to 2022 with MODIS imagery. In the 2019–2022 test set, the GSTFEN was achieved in the annual average of the root mean square error (RMSE), mean absolute error (MAE), and coefficient of determination (R2) of 0.591 t/hm2, 0.475 t/hm2, and 0.848, respectively, thus outperforming the baseline models by 7%-40%. Scatter plot analysis showed that the GSTFEN predictions closely followed the 1:1 line, where the most counties were observed in the absolute errors below 0.5 t/hm2. It was totally different from the conventional models with the large deviations in the high- and low-yield regions. The spatial error maps indicate that the larger residuals were concentrated mainly in northwestern and southwestern areas, with the fragmented fields and mixed pixels. While the major producing regions, such as the Huang–Huai–Hai Plain, also exhibited low prediction errors and high spatial consistency. Ablation experiments confirm that the dual CNN–ViT architecture, the CAFM, and the temporal encoder with Transformer greatly contributed to the accuracy and stability. Moreover, the annual average RMSE at the sowing-to-heading stage differed by only 2.31% from that at the sowing-to-maturity stage. The GSTFEN can be expected to effectively predict the large-scale yield of the winter wheat approximately one month before harvest. While the prediction accuracy was maintained early in the season at the county scale. These findings can provide a strong reference to extract the global–local spatiotemporal features for the yield prediction of the cereal crops.

     

/

返回文章
返回