Implantação da rede de referência cadastral municipal para Monte Carmelo - MG

Abstract

This study presents the implementation of the Municipal Cadastral Reference Network (RRCM) of Monte Carmelo, Minas Gerais, Brazil, a geodetic infrastructure designed to link spatial information to a single, well-defined reference frame. Geodetic networks are widely applied in structural deformation monitoring, allowing the detection of millimetric displacements in dams, benchmarks, and buildings. They are also used in rural and urban cadastral systems, providing support for territorial management and urban planning. The implementation followed the guidelines established by the ABNT standards NBR 14166:2022 and NBR 13133:2021. The network consists of nine upper-order vertices (S), whose coordinates were adjusted based on two monuments of the Brazilian Geodetic System (SGB), namely the active station MGMT and the vertex SAT-99658, and eleven primary vertices (P), adjusted using vertices S-007 and SAT-99658 as references. During the quality control stage, the known baseline between MGMT and SAT-99658 presented an average three-dimensional difference of approximately 18 mm, which is compatible with the normative tolerance of 20 mm. The largest polygon formed by the upper-order vertices, with an approximate extension of 16 km, exhibited a three-dimensional error of about 18 mm, equivalent to 1 ppm. This value is within the limits established by the standard, estimated at approximately 26 mm. In the network adjustment, absolute constraints were initially applied, adopting MGMT and S-007 as control points. The global test indicated that the uncertainties provided by the processing software were optimistic by a factor of approximately six, which led to the rescaling of variances prior to the application of the Data Snooping method, in which no outliers were detected. Subsequently, relative constraints were applied to propagate the uncertainties of the control points. For the upper-order vertices, the worst case was observed at vertex S-004, whose 95% confidence uncertainties were approximately 8 mm in latitude, 10 mm in longitude, and 23 mm in height. Among the primary vertices, point P-006 presented the largest uncertainties, with values close to 13 mm, 14 mm, and 38 mm, respectively, at the 95% confidence level. The results demonstrate the geometric reliability of the RRCM, indicating that the adjusted vertices meet the quality standards required for cadastral and cartographic applications.