Extraction of Near-infrared Information from Aerial Photography Using UAV with Supergel Color Filter Aiming for In-situ Tea Growing Monitoring

Optimum timing for tea harvesting has been determined by farmers from visual observations based on their experience and knowledge. The automation of this determination process using imagery monitoring supports tea farmers on their cost and time in the field works. In this study, we attempted to develop a simple method to extract near-infrared signal from using filtered on-board camera with a drone (DJI Inspire1) in order to utilize for monitoring of the tea status. As a result, we recognized that the filtered image derived from Fire color filter (Rosco #19) was effective to extract near-infrared information over pre-harvesting second crop tea garden. Furthermore, we proposed new normalized vegetation index (FFDVI: Fire Filtered Drone Vegetation Index) using this extracted NIR band.