Use of UAV Geoscan 201 for surveying a linear object of the Khiva–Urgench highway

Abstract

The aim of this work is to perform a linear aerial survey of the Khiva–Urgench highway using the Geoscan 210 UAV, the results of which will create orthophotomaps at a scale of 1:1 000, which are necessary for designing bicycle and sidewalk paths along this route. Surveyors of the Applied Geodesy Department of UZGASHKLITI performed a field planned-altitude reference at this object. 48 control points were determined. Characteristic solid contours along the route were chosen as reference points. The binding of control points was carried out from the starting points of the State Geodetic Networks, using satellite receivers (SN 5242498595, 5243499034, 4827155394) in the RTK mode in a radial way, by the calibration method on the ground. The coverage area was 17.4 sq. km. Aerial photography was carried out at a height of 211 m by a Geoscan 201 unmanned aerial vehicle at a scale of 1:500 with a DSC RXIR digital camera with a focal length of 35 mm. Forward overlap of aerial photographs was 70 %, and lateral—50 %. 4 aerial routes were made at this facility, the photography basis was 42 m. The number of aerial photographs at the facility was 3 868 pieces, and the coverage of aerial photography was 300 m. The images and their EXIF files were georeferenced by performing field processing using the Geoscan Planner program. Before the start of field work, the GNSS receiver (Trimble R6) was installed at a known point on the ground and started in static mode (10 Hz). The aircraft has a GNSS receiver (Topcon) operating in fast static mode (10 Hz). The GNSS data on the ground and on board the aircraft are balanced. Image center coordinates are calculated from the base station GNSS receiver data using MAGNET Tools software. Then the data is imported into Agisoft Metashape software for automatic processing. In this case, the coordinates of the image centers were recalculated from the WGS-84 system into the SK-42 (Pulkovo 1942) system adopted in our country. The process of optimization and alignment of aerial photographs was carried out. After that, in order to obtain a high image quality, the orthophoto map was built using a height map built on the basis of a dense point cloud. The result of the work performed are orthophoto maps for the Khiva–Urgench highway, which will be used to design the location of bicycle and sidewalk paths.