Planialtimetric survey on the local topographic plan: comparative study of the results obtained from geodetic and topographic methods

Abstract

The appearance of geodesy through satellites revolutionized the geodesic survey. However, the transformation of the results obtained in surveys of local topographic planes, using the traditional methodology, presents operational problems. A method, in which Earth rotation movements are applied to the Tridimensional Orthogonal Cartesian System in order to transform it into a system of local geodesic terrestrial coordinates, can be used, giving precise results and accuracy compatible to the application. The objective of this study was to obtain a terrain digital model (TDM), based on point coordinates gathered via GPS set on the rapid static method, and to transform them in local coordinates, comparing this model to the one gained from the coordinates determined through electronics tacheometry. To do so, a double frequency GPS receiver and a total station were the equipments used in this survey. The comparative study was done in an area of the city of Santa Maria (RS, Brazil), and the results of local coordinates acquired from the GPS coordinates were compatible with plans of classes B and C, in a scale of 1:1000 or less, as well as with level curves with equidistance of one meter, according to the established by the 89.817/84 decree, or in a scale of 1:2500, with level curves spaced out at one meter and a half, when these refer to specifications of NSSDA.

Key words: geodetic coordinates, local terrestrial coordinates, local geodetic system.