Creation of the high-precision 3D model of the whole region with UAV

In recent years, one of the most rapidly growing fields in geoinformatics has been the three-dimensional terrain modelling, including urban spaces modelling. The main quality criteria in reconstruction of three-dimensional urban model are the accuracy of the model (the accurate positioning of landscape elements in the coordinate system), the realistic visualization of texture of building facades and structures, and the display of urban infrastructure elements. As 3D-modelling technology is developing, the range of applications for geospatial information is also growing, expanding from knowledge management (in tourism sphere, for example) to cartography, engineering, monitoring, etc. Illustrative examples of such projects are the high-precision models of Singapore and Helsinki. The first project of 3D city modelling in the Russian Federation was carried out in 2014 by a group of companies “Geoscan” on the territory of Tomsk city. Following an aerial survey made by unmanned aerial vehicles (UAV), 190 000 images of the survey area (> 320 km2) with a resolution of 3-5 cm/pix were obtained.

This experience has demonstrated all the advantages of using unmanned aerial vehicles for obtaining digital spatial information, which impulsed the launching of the National Technology Initiative project “Creation of a geodetically accurate 3D model of a pilot region in the Russian Federation based on unmanned aerial survey data and GLONASS technologies”. The Tula region was chosen as the pilot region.

Proper organization of field works allowed performing the survey in a short period of time, notwithstanding the vast area of the region. Thus, an aerial survey of 21 districts of the Tula region with an area of more than 25,000 km2 was conducted in 288 days, during which unmanned aerial systems stayed aloft for more than 10,000 hours. Moreover, an aerial photographing of the architectural monuments of the Tula region with a resolution of 1-2 cm/pix was carried out by a separate team with the use of Geoscan 401 quadcopter.

Analysis and processing of the surveyed data for the purposes of creating orthomosaics and terrain models were carried out in the company’s office with the use of the software for automated photogrammetric processing – Agisoft PhotoScan Pro. The volume of images per one district usually amounted several hundreds of thousands (for example, during the survey of the Alexinsky district with an area of about 950 km2, 269 flights were conducted and 250,000 images were obtained), so this amount of data required colossal powers for the data processing and storage. To solve this problem, the company’s own computational cluster and the computational cluster of the supercomputer Polytechnic RSK Tornado, the peak performance of which reaches 943 Tflops, were used. During the project, 300,000 Tflops of the calculations were performed with its use.

Ultimately, all the necessary materials were obtained in the course of the work: DTMs, DEMs and orthomosaics, realistic 3D models of settlements and monuments. These materials meet the accuracy requirements for cadastral works and can be used for these purposes, as well as for touristic services, the organization of monitoring, territories management and for other purposes. The created Geoportal allows storing and updating spatial information and provides access to the resource for the local authorities and cadastral engineers.

As a result of performed works, violations of land legislation and errors of the cadaster and real estate registration were identified, zoning of territories was carried out and the potential economic impact of violations eliminating was determined. The potential economic impacts from the registration and taxation of the illegally used land plots (land grabbings) accounts for 3.4 bln roubles of one-time revenues and 165 mln roubles of annual revenues (according to NEO Center estimates), while the volume of the annual crop yields of the unused or inappropriately used agricultural lands amounts 5 bln roubles.

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