Inst. Geodäsie und Geoinformationstechnik

53 Items

Recent Submissions
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...

Assessment of Different Stochastic Models for Inter-System Bias between GPS and BDS

Jiang, Nan ; Xu, Tianhe ; Xu, Yan ; Xu, Guochang ; Schuh, Harald (2019-04-25)

Inter-system bias (ISB) will affect accuracy and processing time in integrated precise point positioning (PPP), and ISB stochastic models will largely determine the quality of ISB estimation. Thus, the impacts of four different stochastic models of ISB processing will be assessed and studied in detail to further reveal the influence of ISB in positioning. They are ISB-PW considering ISB as a pi...

Estimating the Impact of Global Navigation Satellite System Horizontal Delay Gradients in Variational Data Assimilation

Zus, Florian ; Douša, Jan ; Kačmařík, Michal ; Václavovic, Pavel ; Dick, Galina ; Wickert, Jens (2018-12-28)

We developed operators to assimilate Global Navigation Satellite System (GNSS) Zenith Total Delays (ZTDs) and horizontal delay gradients into a numerical weather model. In this study we experiment with refractivity fields derived from the Global Forecast System (GFS) available with a horizontal resolution of 0.5°. We begin our investigations with simulated observations. In essence, we extract t...

Improving GNSS Zenith Wet Delay Interpolation by Utilizing Tropospheric Gradients: Experiments with a Dense Station Network in Central Europe in the Warm Season

Zus, Florian ; Douša, Jan ; Kačmařík, Michal ; Václavovic, Pavel ; Balidakis, Kyriakos ; Dick, Galina ; Wickert, Jens (2019-03-21)

The Benchmark data set collected within the European COST Action ES1206 has aimed to support the development and validation of advanced Global Navigation Satellite System (GNSS) tropospheric products, in particular high-resolution zenith delays and tropospheric gradients. In this work we utilize this unique data set to show that the interpolation of GNSS Zenith Wet Delays (ZWDs) can be improved...

Exploration of a Halley-type comet and its debris through meteor observations and modelling

Margonis, Anastasios (2019)

This work focuses on the cm-to-mm sized dust particles of the Perseid meteoroid stream, which is well known to originate from the parent comet 109P/Swift-Tuttle. The main objective of the thesis is the characterisation of the stream through dedicated observations of the Perseid meteor shower using the Smart Panoramic Optical Sensor Head (SPOSH) camera system. A series of observing campaigns hav...

Evaluating Impact of Rain Attenuation on Space-borne GNSS Reflectometry Wind Speeds

Asgarimehr, Milad ; Wickert, Jens ; Reich, Sebastian (2019-05-03)

The novel space-borne Global Navigation Satellite System Reflectometry (GNSS-R) technique has recently shown promise in monitoring the ocean state and surface wind speed with high spatial coverage and unprecedented sampling rate. The L-band signals of GNSS are structurally able to provide a higher quality of observations from areas covered by dense clouds and under intense precipitation, compar...

Validation of 7 Years in-Flight HY-2A Calibration Microwave Radiometer Products Using Numerical Weather Model and Radiosondes

Wu, Zhilu ; Wang, Jungang ; Liu, Yanxiong ; He, Xiufeng ; Liu, Yang ; Xu, Wenxue (2019-07-08)

Haiyang-2A (HY-2A) has been working in-flight for over seven years, and the accuracy of HY-2A calibration microwave radiometer (CMR) data is extremely important for the wet troposphere delay correction (WTC) in sea surface height (SSH) determination. We present a comprehensive evaluation of the HY-2A CMR observation using the numerical weather model (NWM) for all the data available period from ...

Improving the Performance of Multi-GNSS (Global Navigation Satellite System) Ambiguity Fixing for Airborne Kinematic Positioning over Antarctica

Li, Min ; Xu, Tianhe ; Flechtner, Frank ; Förste, Christoph ; Lu, Biao ; He, Kaifei (2019-04-25)

Conventional relative kinematic positioning is difficult to be applied in the polar region of Earth since there is a very sparse distribution of reference stations, while precise point positioning (PPP), using data of a stand-alone receiver, is recognized as a promising tool for obtaining reliable and accurate trajectories of moving platforms. However, PPP and its integer ambiguity fixing perfo...

The Impact of Estimating High-Resolution Tropospheric Gradients on Multi-GNSS Precise Positioning

Zhou, Feng ; Li, Xingxing ; Li, Weiwei ; Chen, Wen ; Dong, Danan ; Wickert, Jens ; Schuh, Harald (2017-04-03)

Benefits from the modernized US Global Positioning System (GPS), the revitalized Russian GLObal NAvigation Satellite System (GLONASS), and the newly-developed Chinese BeiDou Navigation Satellite System (BDS) and European Galileo, multi-constellation Global Navigation Satellite System (GNSS) has emerged as a powerful tool not only in positioning, navigation, and timing (PNT), but also in remote ...

Geometric Refinement of ALS-Data Derived Building Models Using Monoscopic Aerial Images

Jarząbek-Rychard, Małgorzata ; Maas, Hans-Gerd (2017-03-16)

Airborne laser scanning (ALS) has proven to be a strong basis for 3D building reconstruction. While ALS data allows for a highly automated processing workflow, a major drawback is often in the point spacing. As a consequence, the precision of roof plane and ridge line parameters is usually significantly better than the precision of gutter lines. To cope with this problem, the paper presents an ...

Global and regional gravity field recovery by combining satellite, air-shipborne and terrestrial gravimetry data

Lu, Biao (2019)

One basic research field of geodesy or Earth system science is to develop and apply new methodologies and algorithms for gravity field modeling, in particular based on data from the dedicated satellite gravity missions Challenging Minisatellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), Gravity field and steady-state Ocean Circulation Explorer (GOCE) and Gravity Recovery ...

GNSS inter-system bias estimation, modeling, and prediction

Jiang, Nan (2019)

Up to now, the precise point positioning (PPP) has stepped from the single system mode into the multi-GNSS combination. The key point of multi-GNSS integrated PPP is to carefully calibrate the inter-system-bias (ISB) between different systems. If ISB can be modeled, this error will be well corrected. It will significantly increase the usability of satellites and enhance compatibility and intero...

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...

Frame tie based on VLBI observations to near-field spacecraft

Liu, Li (2019)

The objective of this work is to find approaches to realize the link of celestial reference frames, the dynamic spacecraft reference frame and the more stable and accurate International Celestial Reference Frame (ICRF), by observing the spacecraft with Very Long Baseline Interferometry (VLBI). In this work, the phase referencing observations to Global Navigation Satellite System (GNSS) satellit...

Exploration and optimized siting of geothermal wells using a web-based spatial decision support system

Mwaura, Daniel Waweru (2018)

As the world develops and economies grow, there is a commensurate rise in the demand for energy. Many current approaches of fulfilling the increased demand have led to increased pollution through emission of greenhouse gases. A lot of current research in the energy sector is therefore geared towards green and reliable energy sources. Geothermal energy production is one of the leading sources o...

Application of artificial intelligence in Geodesy – A review of theoretical foundations and practical examples

Reiterer, Alexander ; Egly, Uwe ; Vicovac, Tanja ; Mai, Enrico ; Moafipoor, Shahram ; Grejner-Brzezinska, Dorota A. ; Toth, Charles K. (2010)

Artificial Intelligence (AI) is one of the key technologies in many of today's novel applications. It is used to add knowledge and reasoning to systems. This paper illustrates a review of AI methods including examples of their practical application in Geodesy like data analysis, deformation analysis, navigation, network adjustment, and optimization of complex measurement procedures. We focus on...

The calculation of the lunar series on classic Maya monuments

Fuls, Andreas (2007)

Archaeological and historical evidence clearly shows that the Lunar Series of mythical dates were calculated backward—that is, they were often determined from the date on which the monument was erected using a specific formula to calculate the age of the moon. In this article, I present a high-precision adjustment technique that confirms the “Palenque formula” using Lunar Series data from recen...

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...

Tidal deformation of planets and satellites

Steinbrügge, Gregor (2018)

In this thesis, methods are developed and studied for radar and laser altimetry to measure radial tidal deformations of planets and satellites. The thesis investigates further how the tidal measurement allows constraining the interior structure and rheologic properties of the bodies. A semi-analytical performance model for laser altimetry has been developed to predict probability of false detec...

Grammar-guided reconstruction of semantic 3D building models from airborne LiDAR data using half-space modeling

Wichmann, Andreas (2018)

For several years, digital 3D city models have taken a central role in a number of different tasks. These models are used in urban and regional planning, surveying, and navigation and telecommunication technology. They also enable in the environmental field precise analyses and simulations of pollutant, flood, and noise propagation. For many applications, realistic building models are an essent...