FG Geodäsie und Ausgleichungsrechnung

9 Items

Recent Submissions
Modellbildungen zur Signalweg- und in-situ Referenzpunktbestimmung von VLBI-Radioteleskopen

Lösler, Michael (2021)

Die Erde befindet sich in einem kontinuierlichen Wandel, der aus verschiedenen variierenden dynamischen Prozessen und einwirkenden Kräften resultiert. Die globale Erderwärmung, der Anstieg des Meeresspiegels oder tektonische Verschiebungen sind einige der globalen Phänomene, die diesen Veränderungsprozess sichtbar machen. Um diese Veränderungen besser zu verstehen, deren Ursachen zu analysieren...

Weighted Total Least Squares (WTLS) Solutions for Straight Line Fitting to 3D Point Data

Malissiovas, Georgios ; Neitzel, Frank ; Weisbrich, Sven ; Petrovic, Svetozar (2020-08-29)

In this contribution the fitting of a straight line to 3D point data is considered, with Cartesian coordinates xi, yi, zi as observations subject to random errors. A direct solution for the case of equally weighted and uncorrelated coordinate components was already presented almost forty years ago. For more general weighting cases, iterative algorithms, e.g., by means of an iteratively lineariz...

Mean Shift versus Variance Inflation Approach for Outlier Detection—A Comparative Study

Lehmann, Rüdiger ; Lösler, Michael ; Neitzel, Frank (2020-06-17)

Outlier detection is one of the most important tasks in the analysis of measured quantities to ensure reliable results. In recent years, a variety of multi-sensor platforms has become available, which allow autonomous and continuous acquisition of large quantities of heterogeneous observations. Because the probability that such data sets contain outliers increases with the quantity of measured ...

Variance Reduction of Sequential Monte Carlo Approach for GNSS Phase Bias Estimation

Tian, Yumiao ; Ge, Maorong ; Neitzel, Frank (2020-04-03)

Global navigation satellite systems (GNSS) are an important tool for positioning, navigation, and timing (PNT) services. The fast and high-precision GNSS data processing relies on reliable integer ambiguity fixing, whose performance depends on phase bias estimation. However, the mathematic model of GNSS phase bias estimation encounters the rank-deficiency problem, making bias estimation a diffi...

New nonlinear adjustment approaches for applications in geodesy and related fields

Malissiovas, Georgios (2019)

This dissertation deals with a class of nonlinear adjustment problems that has a direct least squares solution for certain weighting cases. In the literature of mathematical statistics these problems are expressed in a nonlinear model called Errors-In-Variables (EIV) and their solution became popular as total least squares (TLS). The TLS solution is direct and involves the use of singular value...

The measurement- and model-based structural analysis for damage detection

Wu, Cheng-Chieh (2019)

The present work is intended to make a contribution to the monitoring of civil engineering structures. The detection of damage to structures is based on the evaluation of spatially and temporally distributed hybrid measurements. The acquired data can be evaluated purely geometrically or physically. It is preferable to do the latter, since the cause of damage can be determined by means of geomet...

Validation and Assessment of Multi-GNSS Real-Time Precise Point Positioning in Simulated Kinematic Mode Using IGS Real-Time Service

Wang, Liang ; Li, Zishen ; Ge, Maorong ; Neitzel, Frank ; Wang, Zhiyu ; Yuan, Hong (2018-02-23)

Precise Point Positioning (PPP) is a popular technology for precise applications based on the Global Navigation Satellite System (GNSS). Multi-GNSS combined PPP has become a hot topic in recent years with the development of multiple GNSSs. Meanwhile, with the operation of the real-time service (RTS) of the International GNSS Service (IGS) agency that provides satellite orbit and clock correctio...

Total Least Squares Spline Approximation

Neitzel, Frank ; Ezhov, Nikolaj ; Petrovic, Svetozar (2019-05-22)

Spline approximation, using both values yi and xi as observations, is of vital importance for engineering geodesy, e.g., for approximation of profiles measured with terrestrial laser scanners, because it enables the consideration of arbitrary dispersion matrices for the observations. In the special case of equally weighted and uncorrelated observations, the resulting error vectors are orthogona...

Determination of intensity-based stochastic models for terrestrial laser scanners utilising 3D-point clouds

Wujanz, Daniel ; Burger, Mathias ; Tschirschwitz, Felix ; Nietzschmann, Tassilo ; Neitzel, Frank ; Kersten, Thomas P. (2018-07-07)

Recent advances in stochastic modelling of reflectorless rangefinders revealed an inherent relationship among raw intensity values and the corresponding precision of observed distances. In order to derive the stochastic properties of a terrestrial laser scanner’s (TLS) rangefinder, distances have to be observed repeatedly. For this, the TLS of interest has to be operated in the so-called 1D-mod...