A COMPARATIVE STUDY OF MACHINE LEARNING CLASSIFIERS FOR CROP TYPE MAPPING USING VEGETATION INDICES
Keywords: Crop Type Mapping, Sentinel-2, Vegetation Indices, Random Forest, GBoost, KNN
Abstract. Timely and accurate mapping of crops is crucial for agriculture management, policy-making, and food security. Due to the differences in the product calendars of various crops, it is possible to classify them by investigating the remote sensing Vegetation Indices (VIs) during crop growth season. This study developed a VI-based mapping approach to specifying crop types based on phenological and spectral metrics derived from the sentinel-2 images. We used six spectral VIs (ARVI, CVI, EVI, LAI, GLI, and NDVI) in three supervised machine learning methods, including Random Forest (RF), GBoost (GB), and K-Nearest Neighborhood (KNN) for crop mapping. Field data consisting of wheat, barley, canola, vegetables, and a bare land class, were collected as the testing and training data set. The classification results were evaluated through test samples showing high overall accuracy (OA) and satisfactory class accuracies for the most dominant crop types across different fields despite the variability of planting and harvesting dates. Among the VIs utilized to crop mapping, the Atmospherically Resistant Vegetation Index (ARVI) in all three classification methods achieved better results. The overall accuracy of RF, GB, and KNN models with the ARVI index was 95%, 88%, and 90%, respectively.