ACCURACY ANALYSIS OF TOPOGRAPHIC MAP BASED ON UAV OBLIQUE PHOTOGRAPHY TECHNOLOGY

With the continuous advancement and development of urbanization, the construction of digital cities is accelerating, and all fields are inseparable from the support of spatial geographic information, especially for the rapid acquisition and update of large-scale topographic maps. Traditional aerial photogrammetry topographic map has strict requirements on airspace, airport, and weather conditions, and has the defects of high cost and long operation cycle, which largely restricts the application of digital photogrammetry technology in large-scale topographic surveying and mapping. At present, the UAV oblique photography technology to produce digital 3D models has also been widely used in digital city construction, city management and emergency disaster relief. This technology can obtain higher resolution images during flight. It has low cost and can effectively make up for the shortcomings of conventional aerial survey methods. It has a wide range of application prospects in obtaining spatial geographic information, especially in surveying and mapping large-scale topographic maps. In this paper, taking the survey area of the test area as an example, the field process of UAV oblique photography and Smart3D Capture software are used for internal data processing, and the digital three-dimensional model produced by oblique photography is produced by DP-Modeler software. The accuracy standard of 1:500 scale for 3D model surveying and mapping based on UAV oblique photographic halo detection is verified, and the analysis error of height accuracy is 0.628m, which can meet the accuracy requirement of 1:2000 scale. In the areas with poor elevation accuracy in the vegetation-covered areas, a square grid algorithm is proposed to improve the elevation accuracy. After filtering by the grid algorithm, the elevation points are generated to generate a topographic map and the error in the interpolation of the check point elevation is 0.887m, and the accuracy is improved by 40%, which greatly improves the elevation accuracy of the topographic map and has certain guiding significance for actual production.