A UAV–RTK Lidar System for Wave and Tide Measurements in Coastal Zones

AbstractA lightweight and low-cost unmanned aerial vehicle (UAV) system for coastal wave and tide measurements is developed. This system is based on an assembly of a multirotor UAV, a robotic light detection and ranging (lidar), an altitude and heading reference system (AHRS), and a real-time kinematic (RTK) global navigation satellite system (GNSS). A great advantage of the system is that it can be operated at low altitude in few meters; the accuracy and spatial resolution can therefore be increased. When the system was moved up and down in 2 to 12 m, the root-mean-square error (RMSE) was approximately 5 cm compared to the ground truth value measured by a manual RTK-GNSS. The system was operated in a hover mode to measure the tide and waves in the field. The results of using the UAV-RTK-lidar system were consistent with those of in situ measurements using a pressure sensor. The root-mean-square errors between the two techniques for measurements of tidal elevation, significant wave height, and wave period...