Landslide Deformation Analysis Based on Robust M-estimations

Abstract

There are often occurs a cases in surveying practice, when periodical observations of horizontal landslide areas displacements or different objects is necessary to evaluate in the local coordinate system. The reasons, for which some local coordinate systems are still using, even in the present time of global navigation satellite systems (GNSS), are different. It is above all the facts that till the put in practice of GNSS technology, the deformation analysis was carried out in national cartographic coordinate system. If the density and accuracy of geodetic bases not guarantee the required accuracy, deformation analysis is carried out in geodetic network structures located in the local coordinate systems. The advantage of this approach is that horizontal point displacements were evaluated in pur - pose-designed coordinate system with minimizing mathematical corrections of observation such as correction from height above sea level or from distortions of a map projection. Another reason for limiting the use of GNSS may be the fact that the signal reception can be considerably restricted inside of steep and narrow mountain valleys, near to rock walls or in areas with dense vegetation. The most serious problem of periodical evaluation of positional points displacements in the local geodetic network are primarily risks associated with the change of geodetic networks datum in the local coordinate system as a result of positional instability of one or more reference points. The paper presents a way how can be the discussed problem, at least partially, eliminated by the use of robust M-estimates.