ANALYSIS OF GOOGLE EARTH ALTITUDE ERRORS FOR USE IN GEODESIC WORKS

Abstract

The Google Earth service is an information system with extensive functionality used in the Internet, for mobile devices and for desktop computers. The system is a "virtual globe" built on pooled photographs with the addition of spatial information provided by Alphabet Inc in the coordinate system - WGS 84 and the universal cross-section of Mercator. In the system there is an opportunity to lay a line of a route, to receive a longitudinal profile of this line with marks and a slope. However, the question of the accuracy of spatial information remains. The answer to this question will highlight a range of engineering, geodetic and design tasks that can be solved with this service. The article considers this problem from the analysis of height errors. The accuracy of Google Earth's spatial information can be assessed by comparing it to a geodetic reference object. As such object in this work the data of adjustment of the design documentation for construction of the highway bypassing Novy Bug (the second turn) in the Nikolaev area are taken. In the first stage, a "reference" object has been considered, for which there are spatial data obtained by geodetic methods of a given accuracy. In the second stage, the Google Earth system built a road route and a longitudinal profile. At the third stage the received information was systematized and analyzed. In this work, the accuracy of construction of the longitudinal profile by geodetic methods was reduced due to the construction of a black line of the longitudinal profile through a digital terrain model, and hence due to the standard errors of Delaunay triangulation. When using geometric leveling data, the compatibility of the two longitudinal profiles will increase. With careful preparation of the original data, you can achieve meter accuracy in height. Representation of the Earth's surface with such accuracy can be used in solving many engineering problems: variant design of linear structures, preliminary feasibility study of design solutions and more. In the future, we must to assess the horizontal errors.