Research On Key Technologies In The Application Of Low Altitude UAV Without Image Control Measuring And Producing DOM Of Large-scale Mapping

As an emerging surveying and mapping technology,UAV photogrammetry technology has been widely used in the production of surveying and mapping geographic information products such as digital orthophoto map and digital elevation model with many advantages such as high efficiency,quickness,lightness and flexibility.It has become a favored technical means and research direction in the field of surveying and mapping geographic information.Although unmanned aerial vehicle photogrammetry technology has incomparable advantages over remote sensing technology and traditional surveying and mapping methods,there are still many problems to be solved in actual production and application.For example,the flight attitude of the UAV is not stable,which is easily affected by the external environmental conditions.The accuracy of airborne POS data is not high,which affects the accuracy of subsequent data processing and mapping.The small size and large number of images taken increase the work of data processing.It is difficult to measure the field control points when the terrain is more complex.In this paper,the UAV photogrammetry system as a technical means,through specific experiments to explore the UAV aerial photography system in the process of mapping and mapping of several key problems to solve the solution,and through the accuracy evaluation and analysis confirmed the feasibility of the solution.The main content includes the following three aspects:(1)It is difficult to maintain the stability of POS system under complex conditions,which may lead to gross error.In this paper,a method of POS data analysis and repair based on Kalman filter is studied.The results show that the method can eliminate the influence of POS data error better,and then be used in empty three solution,and complete the data processing work smoothly.(2)The non-reference image quality evaluation algorithm based on spatial entropy and spectral entropy was adopted to carry out quantitative quality analysis on massive UAV images,and the impact of UAV image refinement processing based on quantitative evaluation indexes was studied and compared.The results show that using this method to refine and screen UAV images can improve the efficiency of data processing while ensuring the image accuracy.(3)Aiming at the actual problem that large elevation errors are likely to occur in the imagefree mapping of UAV under complex conditions,this paper proposes an error correction method based on high-precision elevation points in the overlapping area for the correction of elevation errors.Based on the actual production project of unmanned aerial vehicle image-free surveying and mapping in a section of actual highway survey and design,this paper uses Sirius UAV to collect the actual engineering data,analyzes the data obtained and processed by UAV imagefree control,and carries out accuracy evaluation and analysis through experiments.