Tsoulias Nikos, Jörissen Sven, Nüchter Andreas
Department Horticultural Engineering, Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Max-Eyth-Allee, Potsdam 14469, Germany.
Department of Informatics VII-Robotics and Telematics, Julius-Maximilians-University Würzburg, Würzburg 97074, Germany.
MethodsX. 2022 Apr 26;9:101712. doi: 10.1016/j.mex.2022.101712. eCollection 2022.
Heat and excessive solar radiation can produce abiotic stresses during apple maturation, resulting fruit quality. Therefore, the monitoring of temperature on fruit surface (FST) over the growing period can allow to identify thresholds, above of which several physiological disorders such as sunburn may occur in apple. The current approaches neglect spatial variation of FST and have reduced repeatability, resulting in unreliable predictions. In this study, LiDAR laser scanning and thermal imaging were employed to detect the temperature on fruit surface by means of 3D point cloud. A process for calibrating the two sensors based on an active board target and producing a 3D thermal point cloud was suggested. After calibration, the sensor system was utilised to scan the fruit trees, while temperature values assigned in the corresponding 3D point cloud were based on the extrinsic calibration. Whereas a fruit detection algorithm was performed to segment the FST from each apple.•The approach allows the calibration of LiDAR laser scanner with thermal camera in order to produce a 3D thermal point cloud.•The method can be applied in apple trees for segmenting FST in 3D. Whereas the approach can be utilised to predict several physiological disorders including sunburn on fruit surface.
在苹果成熟过程中，高温和过多的太阳辐射会产生非生物胁迫，从而影响果实品质。因此，在苹果生长期间监测果实表面温度（FST）可以确定阈值，超过该阈值，苹果可能会出现晒伤等多种生理失调现象。目前的方法忽略了FST的空间变化，且重复性降低，导致预测结果不可靠。在本研究中，利用激光雷达（LiDAR）激光扫描和热成像技术通过三维点云检测果实表面温度。提出了一种基于有源板靶标对两个传感器进行校准并生成三维热学点云的方法。校准后，利用传感器系统对果树进行扫描，而在相应三维点云中分配的温度值基于外部校准。同时，采用果实检测算法从每个苹果中分割出FST。•该方法可对激光雷达激光扫描仪和热成像仪进行校准，以生成三维热学点云。•该方法可应用于苹果树上，用于三维分割FST。而且该方法可用于预测包括果实表面晒伤在内的多种生理失调现象。
