Development of UAV-based lidar crop height mapping system

Crop height monitoring is important to appropriate field management. Previous studies have indicated that a Light Detection and Ranging (LiDAR) sensor was capable of accurate and fast data collection. As technology of Unmanned Aerial Vehicles (UAV) advanced, the airborne LiDAR system became a promising remote sensing based method for non-destructive crop height measurement. The objective of this study was to develop a UAV-based LiDAR system for crop height measurement. The system consisted of a 360-degree 2D laser scanner and an onboard computer mounted on an open source UAV platform. A data processing and visualization algorithm was developed to process dense spatial point cloud data and generate a crop height map of the target field. Outdoor experiments were conducted in a real corn field to evaluate the height measurement performance of the UAV-based LiDAR system. The results show that the average R2 value of 0.87, average mean error (absolute error) of 4.47% and average RMSE of 0.143 m, were achieved in comparison with manual measurements. The UAV-based LiDAR system could cover a 2 acre corn field within eight and half minutes, saving about 90% operation time compared with a tractor-based LiDAR system. The UAV-based LiDAR system developed in this study demonstrated its accurate and efficient crop height measurement in a real crop field, and is expected to be applied in practical agricultural production