可視・近赤外カメラによる茶葉摘採時期の決定および樹勢判定

抄録

Method for determination of tealeaves harvest timing with ground based visible and near infrared cameras is proposed together with tea tree vitality assessment. Off-nadir viewing cameras acquire not only tealeaves but also shadow and shaded portions of tealeaves as well as soil surface which depend on illumination conditions of the sun, soil surfaces and winds. In order to avoid these influences on determination of tealeaves harvesting timing, a method to extract tealeaf surfaces of which the tealeaf surfaces are pointing to zenith direction. Relations between Near Infrared : NIR data which is acquired with the proposed ground based NIR camera and nitrogen and fiber contents in tealeaves as well as harvest amount of tealeaves are clarified. Meanwhile, tea tree vitality is defined as nitrogen contents in harvested tealeaves multiplied by harvesting amount per unit area. A method for tea tree vitality estimation with satellite remote sensing visible to near infrared radiometer data which are acquired in February time frame is also attempted. The proposed method is validated with ground truth data of nitrogen and fiber contents in tealeaves and harvest amount of tealeaves. The estimation results of tea tree vitality are displayed on Geographic Information System : GIS together with satellite imagery data and ground truth data. Thus leaf tea producing process can be controlled with the GIS derived information by tea fields.