drone Research & information: general 10 remote sensing 10 machine learning 9 UAV 8 deep learning 7 photogrammetry 7 random forest 7 Sentinel-2 6 hyperspectral 6 CNN 5 NDVI 5 Technology: general issues 5 artificial neural network 5 climate change 5 computer vision 5 multispectral 5 unmanned aerial vehicle 5 vegetation indices 5 History of engineering & technology 4 IoT 4 Landsat 4 SAR 4 UAS 4 artificial intelligence 4 precision agriculture 4 systematic literature review 4 GIS 3 Geography 3 Google Earth Engine 3