Método de estação livre com controle de falsos fixos do posicionamento gnss-rtk: uma aplicação no georreferenciamento urbano

Abstract

The objective of this study is to present a Free Station method supported by coordinate points determined using the RTK (Real Time Kinematic) technique. The proposed method allows the control of false fixes through the residuals of the transformation between the coordinate systems involved. Although it is not included in NBR 17.047, it is considered a rigorous method, as the measurements can be controlled, and it is productive in terms of quality control and obtaining the desired coordinates in real time. The method was applied to an urban property located in the city of Monte Carmelo, Minas Gerais. The study area is characterized as an urban canyon region where no local geodetic network is available. The results show that the uncertainties of the property boundary points averaged 7 mm, with a ~0.68 probability. For verification purposes, the Station coordinate was determined using static relative positioning. The difference between the coordinates estimated by Static Relative Positioning (SRP) and the proposed method was ~9 mm. These differences are within the tolerance of 8 cm specified for urban georeferencing. Additionally, the difference in terms of the building façade length was analyzed. The façade length was measured using a tape measure, as well as calculated using the proposed method and RTK. The results show a difference of 4 mm between the proposed method and the tape measure, 8 mm between the proposed method and RTK, and 1.2 cm between the tape measure and RTK. These differences are within the tolerance specified by NBR 17.047 (6 mm √L, where L is the length determined using the tape measure).Therefore, the proposed method proved suitable for cases requiring urban georeferencing in urban canyon situations and/or locations where no geodetic networks are available.