Fig. 4From: The impact of variable illumination on vegetation indices and evaluation of illumination correction methods on chlorophyll content estimation using UAV imageryThe RGB orthomosaics collected under three different illumination conditions: a the orthomosaic collected on the clear sunny sky with a stable solar irradiance, 14th August. b the orthomosaic collected on a semi-cloudy day with variable solar irradiance, 15th August, and c the orthomosaic collected under the totally overcast day, 18th AugustBack to article page