Two dimensional network adjustment and deformation analysis via MATLAB

Abstract

Network adjustment and deformation monitoring are one of the main activities of engineering surveying. Geodetic networks are estimated by the method of least-squares estimation (LSE) adjustment and the ‘goodness’ of the network is measured by a precision analysis based upon the covariance matrix of the estimated parameters. When such a network is designed, global test and local test are assessed to test compatibility of variance factor via two-tailed chi-square distribution and residual of measurements to detect gross error by using a technique pioneered by the geodesist Baarda. The second step is Deformation detection. Generally, the deformation computations can be divided into geotechnical and geodetic methods. There are two types of geodetic networks, namely the absolute and relative networks. In the absolute network, some of the points are assumed to be located out of the deformable body. However, in a relative network, all points are assumed to be located on the deformable body. This study focuses on two dimension (2-D) absolute geodetic deformation detection via MATLAB7. Deformation analysis can be handled by several techniques such as Robust (IWST and LAS), Congruency, Bayesian method and etc. This study presents a deformation analysis procedure via geodetic methods that consists of LSE of individual epochs, trend analysis of the displacement field and the deformation detection by IWST between epochs. This research focuses on the development of two programs in MATLAB7 for network adjustment (distance, angle and azimuth observation respectively) and deformation detection between two epochs. In this project, first LSE adjustment is done for each epoch and creates the appropriate input files for deformation program. Next, deformation program reads them and creates an output file and displays a graphic consists of error ellipse for each stations and displacement vector for moved stations. There are three data sets to run these two programs. For adjustment part the results are compared with STARNET results and for deformation part the results are compared with previous works by Caspary (1987), Ranjit(1999) and Khairulnizam(2004).The results show that these two programs work and there are not significant difference between these results and results from other works.