Ordenação dos parâmetros para ajustamento e análise da qualidade de redes geodésicas altimétricas geométricas

Abstract

In altimetric geodetic surveys, according to the kind of its usage, it is necessary to know the quality of those estimated altitudes. In order to do so, in Geodesy, the adjustment of estimated measurements and/or parameters is used, being the criterion of minimum squares used, not only for the Parametric Model but also the Correlate one or the Combined one. It is common the concept and the methodological development in literature in general cases of adjustment. The development for specific cases might not be a trivial task for the ones who are not directly familiar with this matter, like computing system programmers. This paper aims to order, in a didactic way, the necessary procedures of altimetric geodetic nets adjustment and quality analisys by using the Parameter Model in order to facilitate the implementation of programmable routines. Based on those procedures, processing routines in Matlab 5.1 have been implemented aiming to verify their functioning in a practical test provided with real data. To do so, an altimetric assessment of a geodetic net of ten points, with a level NI2 of KARL ZEISS was carried out. Eight out of these points needed to know their altimetric coordinates and in two out of these points their heigts were already known, points which are called here as injunction ones, PAI and PA2, from which the assessment was attached to. From the leveling of these points seventeen (17) unevenness were obtained. By using those data taken in the field, an adjustment of this net was made by the parametrical model of the minimum square method. After the adjustment, analysis of the adjustment itself was made through the statistics of the quisquare test for the detection of gross mistakes, where the variants of weight unit were compared before and after it. In this evaluation, a difficulty of framing the adjustment inside the area of acceptance was observed and it was needed to alter the initial standard deviation (nominal) of the instrument. This demonstrated the necessity of having checking of those instruments used in order to know their real values of precision during their useful lives so that the data taken from them can be used in safety. Also, a calculus of the redundancy matrix and its trace and the snooping data test of Baarda were carried out. The data, the values calculated and the routines are shown here