CerealNet: A Hybrid Deep Learning Architecture for Cereal Crop Mapping Using Sentinel-2 Time-Series

Abstract

Remote sensing-based crop mapping has continued to grow in economic importance over the last two decades. Given the ever-increasing rate of population growth and the implications of multiplying global food production, the necessity for timely, accurate, and reliable agricultural data is of the utmost importance. When it comes to ensuring high accuracy in crop maps, spectral similarities between crops represent serious limiting factors. Crops that display similar spectral responses are notorious for being nearly impossible to discriminate using classical multi-spectral imagery analysis. Chief among these crops are soft wheat, durum wheat, oats, and barley. In this paper, we propose a unique multi-input deep learning approach for cereal crop mapping, called “CerealNet”. Two time-series used as input, from the Sentinel-2 bands and NDVI (Normalized Difference Vegetation Index), were fed into separate branches of the LSTM-Conv1D (Long Short-Term Memory Convolutional Neural Networks) model to extract the temporal and spectral features necessary for the pixel-based crop mapping. The approach was evaluated using ground-truth data collected in the Gharb region (northwest of Morocco). We noted a categorical accuracy and an F1-score of 95% and 94%, respectively, with minimal confusion between the four cereal classes. CerealNet proved insensitive to sample size, as the least-represented crop, oats, had the highest F1-score. This model was compared with several state-of-the-art crop mapping classifiers and was found to outperform them. The modularity of CerealNet could possibly allow for injecting additional data such as Synthetic Aperture Radar (SAR) bands, especially when optical imagery is not available.

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Early Crop Mapping Using Dynamic Ecoregion Clustering: A USA-Wide Study

“…Another research [11] effort concentrates on creating a high-resolution crop intensity mapping methodology by integrating data from Landsat-8 and Sentinel-2 satellites using a random forest algorithm. Furthermore, a hybrid deep-learning architecture called CerealNet [21] has been introduced for the specific purpose of cereal crop mapping, utilizing Sentinel-2 time-series data. However, ref.…”

“…However, ref. [21] has limitations in its scope, as it specifically examines a research region characterized by a hot Mediterranean climate with dry summers. This region selection addresses a common challenge posed by cloud cover in time-series data analysis of Landsat-8 and Sentinel-2 images.…”