Abstract: For some non-line-of-sight areas which are blocked by hills and vegetation on elevation transfer routes, an UAV assisted trigonometric leveling method combined with the automatic tracking capability of robotic total station is proposed. The principle is that two robotic total stations with synchronized clocks take the 360° prism carried by an UAV hovering over the obstacles as the target for dynamic observation, and the height difference between the stations is calculated using synchronized observations. The main factors affecting the accuracy of the method and the countermeasures are analyzed, and the corresponding observation procedures are formulated. The actual test results show that the proposed method can obtain comparable height accuracy and is helpful for rapid height transmission in non-line-of-sight areas.

Key words: trigonometric leveling, UAV, synchronous observation, observation procedures, accuracy analysis