Examination of vertical displacements at non-permanently fixed points

Abstract

The aim of this paper was to analyze vertical displacements in four different test areas, with various types of surfaces, without permanently stabilized measuring: points and control network, using the same measurement method. The first stage involved measuring selected test areas with a number of measuring points that reliably reflect the surface and to construct the DEM. The second stage involves acquiring of a grid of control points, evenly distributed in the test area, used to assess the accuracy of the DEM. The last stage involved the analysis of the acquired results, including the application of an original program to calculate vertical displacements. In order to conduct the analysis the “blind test” was introduced, which allowed to perform formal analyses, i.e. verification of the accuracy of models constructed based on direct measurements. In this program (based on the IDW interpolation method), the study of the dependence of introducing fixed points (given measurement error), to measured survey points was carried out. It was possible to determine vertical displacements between measurements in each area, calculate the accuracy of the mapping of the terrain surface, fit the DEM into the actual terrain, as well as obtain the parameters of the approximate planes.