Accuracy Analysis Of UAV Photogrammetry Surveying And Mapping Large-scale Topographic Map

Large-scale topographic maps are one of the indispensable basic data for urban planning and design [1].Traditional surveying and mapping technology is difficult to complete surveying and mapping tasks efficiently due to the influence of environment,terrain and other conditions.In recent years,with the rapid development of science and technology,more and more new technologies have emerged in the field of surveying and mapping,especially the low-altitude photogrammetry method of drones.UAV low-altitude photography has the advantages of speed,efficiency,and low labor intensity.It not only optimizes the operation mode and process of traditional surveying,but also effectively reduces the accumulation of errors and improves operation efficiency.It has a good performance in large-scale topographic map surveying and mapping.Application prospects.This article focuses on the rapid acquisition of large-scale topographic maps using UAV photogrammetry,expounds in detail the principles,key technologies and specific operation steps of UAV low-altitude photogrammetry,and analyzes the impact of photogrammetry technology on the accuracy of large-scale topographic maps.Factors and precautions.Comparison of drone photogrammetry technologies and traditional surveying and mapping technologies in terms of operational accuracy,efficiency and equipment performance,and how to improve measurement accuracy has been done as follows:(1)This article gives a distortion correction model.It is verified by experiments that it is feasible to use the straight line constraint method to solve the distortion coefficient,and the direct correction method can make the distortion image get better correction.After the actual resolution of the ground has been determined,the location and method of the camera placement during shooting will affect the accuracy of the indoor elevation data collection.Experiments have found that the short side of the camera's CCD array is most conducive to improving the accuracy of indoor elevation data collection when it is placed perpendicular to the direction of the route.(2)Layout of image control points.Regarding the layout of image control points,there is no clear specification requirement.As a result,there are factors such as unclear image control point layout and unstable accuracy in the operation.Based on this,this article proposes eight image control point layout schemes.The image data obtained using each scheme is processed by Pix4 D and Context Capture respectively.The obtained results are compared and verified and analyzed,and it is concluded that the scheme is applied to vertical photography and The feasibility,reliability and efficiency of oblique photography.As for the position of the image control point,there is no clear specification requirement.(3)Image quality.The system checks and compares the original images and POS data obtained by different UAVs in the two survey areas,and deeply analyzes the key factors that affect the quality of UAV images in the survey area.(4)Image matching.The principle of the commonly used binary robust scale invariant feature BRISK algorithm and the scale invariant feature SIFT algorithm are introduced in detail.According to their characteristics,the BRISK-SIFT combined algorithm is proposed,and the three algorithms are used to perform matching experiments on different tilted images.Analyze the matching advantages of the BRISK-SIFT algorithm based on the matching effect.(5)Comprehensive comparative analysis.Through comparative analysis of the advantages and disadvantages of using drone photogrammetry technology to produce large-scale topographic maps,the advantages of new technology and traditional measurement technology in terms of operating accuracy,operating efficiency,operating methods,safety,and personnel professionalism are discussed in depth.,Through comprehensive comparative analysis,provide a reference for flexible selection of operation mode in the future.