The accuracy of foundation pit displacement observation based on UAV orthophoto maps
Horizontal displacement changes of foundation pits is an important indicator for its deformation monitoring,it is crucial for safety assessment of the foundation pit to quickly and accurately obtain the displacement changes.The conventional monitoring methods use total stations,GNSS,and other means to obtain the coordinates of monitored points,and reflect the displacement changes of the foundation pit through comparison of the data from different periods.However,these methods need great workloads and have low automation,so they have poor accessibility in difficult areas.This paper sets appropriate param-eters for unmanned aerial vehicle(UAV)flights,produces high-precision orthophoto maps of the foun-dation pit using photogrammetric methods,obtains the horizontal coordinates of monitored points,realizes rapid perception of horizontal displacement changes in the foundation pit,and compares it with precise data measured by total station to verify the feasibility of this method.The experimental results show that when the flight altitude is 50 m,the root mean square errors(RMSE)of the point position and distance are 14.3 mm and 14.9 mm,respectively.When the flight altitude is 20 m,the RMSE of the point posi-tion and distance are 7.2 mm and 5.6 mm,respectively.When the UAV flies at a low altitude,the hori-zontal coordinate accuracy of the foundation pit monitored points obtained from UAV orthophoto images is relatively high,which can effectively reflect the displacement changes of the foundation pit and meet the requirements for the error of the third-level horizontal displacement monitoring.
万方数据
维普
