Abstract: Ground imitation flight is a very important issue in aerial survey of unmanned aerial vehicles. Whether the aircraft can maintain a stable altitude relative to the ground which is directly related to the safety and data quality of unmanned aerial vehicles in complex terrain areas. Therefore, a monocular vision based on UAV aerial height estimation method is proposed in this paper. The optical flow method is used to track and analyze the real-time video obtained by UAV, and the motion information is extracted to estimate the real-time aerial height. The experimental results show that this method can estimate the real-time altitude of UAV quickly and accurately, and realize the automatic ground-mimicking flight without the information of surface altitude.

Key words: ground imitation flight, UAV, aerial survey, optical flow, monocular vision