Research On UAV Tilt Photogrammetry Technology In Undulating Areas Of Large Height Difference In Yunnan

With the development of society and the progress of science and technology,the performance of UAV and digital camera is improved and the price is reduced.Many small and medium-sized enterprises begin to buy UAV to complete related engineering projects.The small UAV has the advantages of low cost,simple operation and easy to complete the relevant measurement work.UAV tilt photogrammetry is mainly divided into two parts,field data acquisition and indoor data processing.This paper mainly considers from the overall point of view,analyzes the factors that affect the accuracy of the results: the field stage mainly considers the influence of route design and overlap degree on the accuracy of the results,and the indoor stage mainly considers the influence of route flight mode,image control point layout,and the number of photo prick points on the accuracy of the results.The main work and achievements of this paper are as follows: the research status of UAV tilt photogrammetry is explained,and some existing problems of tilt photogrammetry are analyzed;The basic concepts of oblique photogrammetry are analyzed.The relationship between spatial resolution and mapping scale and the relationship between spatial resolution and aerial photogrammetry scale are analyzed;Based on the analysis of vertical photogrammetry,the relationship between the area of image plane and the area of field on the average elevation plane in the process of oblique photogrammetry is deduced,and the variation trend of the overlap of S-shaped flight and circular flight is analyzed;In view of the characteristics of high elevation and large topographic relief in Yunnan Province,this paper studies whether the mapping accuracy of large-scale topographic map can meet the corresponding standard in plateau surveying and mapping by UAV tilt photogrammetry,and takes the Tianshui Jiayuan area in Chenggong District of Kunming city of Yunnan Province as the research area for 3D modeling.Three kinds of flight modes,i.e.circling flight,zigzag flight and five way flight,were designed.14 control points and 101 checkpoints were measured in the experimental area.Context capture software was used for 3D modeling in the indoor data processing stage,and various data processing methods were designed based on the difference between the checkpoint coordinates measured in the field and the checkpoint coordinates in the 3D model,The influence of different processing methods on the accuracy is analyzed.Conclusion: The results show that the flying around,the flying in well and the flying in five directions all meet the corresponding precision.On the premise of ensuring the precision and quantity of spikes,the precision of the flying around and the flying in five directions are better;In the case of the same number of control points,increasing the number of prick points of each control point can improve the accuracy of the results;The precision of flat land is better than that of high mountain land,and the plane precision is better than the elevation precision;The control points should be evenly distributed in the survey area,and proper spacing should be maintained between different control points.