Abstract
Abstract: The forward intersection method is already widely used in the geodetic survey of coordinates of inaccessible points, especially when only angle measurements are available, in this case, also called the triangulation method. However, the mathematical solution of the 3D forward intersection with the analytical definition of spatial lines, resolved by the Minimum Distances Method, is still not widespread in the academic and professional environment. This mathematical modeling determines the 3D coordinates of a point located in the middle of the minimum distance between two or more spatial lines, which spatially "intersect" towards the observation point. This solution is more accurate than others presented in the literature because it simultaneously solves the problem of 3D determination of a point by the method of least squares, in addition to providing an estimate of the coordinate precision, which are inherent to the adjustment. This work, therefore, has the objective of explaining the Minimum Distances Method for the spatial intersection of targeted measurements with a Total Station from two or more known observation points for the 3D determination of inaccessible points located in corners of buildings. For the analysis of the method, a Python tool was developed for QGIS that calculates the 3D coordinates and generates the adjustment processing report, being applied with real observations of the Geodetic survey of the SUDENE building, in Recife-PE. The methodology developed in this work proved to be suitable for measurements of large structures, achieving spherical precision better than ±1.0 cm, following the Brazilian standards for urban cadastre.
Highlights
The monitoring of engineering structures has the objective of verifying their variations over time, evaluating the stability of the constructions and the resulting risks ( Alves et al, 2012; De Seixas et al, 2007)
The methodology of this work, which integrated GNSS data with the terrestrial planialtimetric measurements collected from Total Station, proved to be efficient for Geodetic surveys of large structures, such as the SUDENE building, achieving spherical precisions better than ±1.0 cm
It can be concluded that the results of this work serve as a reference for the assessment of the 3D positional quality of geodetic surveys of buildings for the urban land register in Brazil, regulated by Decree-Law no 9.310 (BRASIL, 2018), considering that the spherical precision achieved is better than required by law (± 8 cm)
Summary
The monitoring of engineering structures has the objective of verifying their variations over time, evaluating the stability of the constructions and the resulting risks ( Alves et al, 2012; De Seixas et al, 2007). There is a need for continuous monitoring and control of the shape and surface of objects (De Seixas et al, 2014; Mao et al, 2013; De Seixas, 2004) with techniques of adequate accuracy for this purpose. With the advent of Building Information Modeling (BIM), geodetic surveying has become an essential factor in quality control from the beginning to the end of a work (França, 2018), due to the need to check whether the planned (as-planned) files BIM corresponds to the constructed reality (as-build) and if the reality faithfully reflects this set of data, avoiding both loss and excess of BIM elements (Ariza-López et al, 2019), guaranteeing economic benefits in the management of the construction phases ( Mill et al, 2013).
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