Application Research Of UAV Tilt Photogrammetry For Mountain Topography Surveying And Mapping

Oblique photogrammetry technology is a new photogrammetry technology emerging in the field of surveying and mapping in recent years.With the help of UAV platforms,it has the characteristics of flexibility,low cost,and high reliability.This measurement technology greatly reduces the field data collection work.Most of the work is turned to internal processing,which shortens the working time and reduces the operating costs.It is increasingly used in various fields,such as national conditions monitoring,geological disaster investigation,and emergency treatment,especially in large-scale mapping.The results have been widely recognized,and the rapid acquisition of high-resolution images in areas with difficult flight has obvious advantages.At present,using UAV tilt photogrammetry technology to model 3D model,and then using the final 3D model results to produce digital topographic map,which greatly improves the speed of map updating,has a good application prospect for the production of topographic map under special terrain,so how to measure mountain terrain to obtain high-precision large-scale topographic map has always been the research direction.Based on the method of tilt photogrammetry,this paper studies and introduces in detail the principle,system composition and technical characteristics of tilt photogrammetry from the whole production process of 1:500 scale topographic map UAV tilt photogrammetry,and analyzes the main sources of three-dimensional modeling error of UAV tilt photogrammetry,including lens distortion,image control point placement and measurement,prick point and error caused by UAV data acquisition.This paper uses EPS geographic information workstation and ES3 D two-three-dimensional integrated surveying and mapping system as data processing platform to carry on the experiment,finally obtains the conclusion as follows:(1)In the course design of the valley terrain,in order to obtain the same resolution and higher accuracy,the traditional route layout scheme was improved by the slope characteristics of the valley terrain,and a route layout scheme based oncontour lines was proposed;(2)Taking the mountainous terrain survey area as the test area,using the eight-rotor UAV to carry the five-shot tilt photography lens to collect the data,using the Smart 3D software for data processing,using the existing EPS geographic information workstation as the digital line map data acquisition software,using the two-dimensional model and three-dimensional model as the working base map,using the point error as the criterion of accuracy,plane point and elevation accuracy analysis.113 m,0.076 m mean point error,except for two high voltage poles and lower housing foot error is larger,the rest are below 0.05 m,the whole tends to be stable,the checkpoint elevation error value of 0.067 m,all meet the 1:500 scale topographic map accuracy requirements;using the 3D model as the base map,the calculation of 12 checkpoints point error of 0.112 meters,average point error of 0.078 meters,with the exception of two high-voltage poles,the point error is slightly larger,and the rest are below 0.07 meters;At the end of this paper,a set of methods and principles for drawing large scale topographic map of mountainous terrain using twoand three-dimensional model linkage is put forward,which provides substantive suggestions for surveying and mapping actual project production.(3)From the highest point to the lowest point,the accuracy of plane position and elevation position can be obtained.The mean difference of plane position is 0.035 meters,the mean difference of elevation is 0.032 meters,and the accuracy is stable0.069 meters,and its data accuracy fluctuates greatly,in order to make the obtained topographic map accuracy stable everywhere,it is necessary to use the attached contour line design for data acquisition in the mountainous terrain with high height difference to ensure the resolution of each position in the image and 3D model is consistent;(4)Finally,ES3 D software and EPS software were used to compare the plane position and elevation accuracy,as well as the advantages and disadvantages of the collected data.Through the accuracy comparison analysis,it can be concluded that the large-scale topographic maps obtained by the two softwares have the same accuracy and meet the requirements.The accuracy of drawing is required,and the accuracy ofthe surface line intersection point mode unique to the ES3 D software is higher than that of the house foot point acquisition mode in the accuracy of collecting houses.The installation of ES3 D software is more complicated,but its operation is for operators familiar with CAD software Its operation is relatively simple and easier to learn and apply;what really determines the accuracy of DLG is the accuracy of the two or three-dimensional model itself.