<abstract xmlns="http://www.w3.org/1999/xhtml"> Very Long Baseline Interferometry (VLBI) is the only space geodetic technique capable to realise the Celestial Reference Frame and tie it with the Terrestrial Reference Frame. It is also the only technique, which measures all the Earth Orientation Parameters (EOP) on a regular basis, thus the role of VLBI in determination of the universal time, nutation and polar motion and station coordinates is invaluable. Although geodetic VLBI has been providing observations for more than 30 years, there are no clear guidelines how to deal with the stations or baselines having significantly bigger post-fit residuals than the other ones. In our work we compare the common weighting strategy, using squared formal errors, with strategies involving exclusion or down-weighting of stations or baselines. For that purpose we apply the Vienna VLBI Software VieVS with necessary additional procedures. In our analysis we focus on statistical indicators that might be the criterion of excluding or down-weighting the inferior stations or baselines, as well as on the influence of adopted strategy on the EOP and station coordinates estimation. Our analysis shows that in about 99% of 24-hour VLBI sessions there is no need to exclude any data as the down-weighting procedure is sufficiently efficient. Although results presented here do not clearly indicate the best algorithm, they show strengths and weaknesses of the applied methods and point some limitations of automatic analysis of VLBI data. Moreover, it is also shown that the influence of the adopted weighting strategy is not always clearly reflected in the results of analysis.</abstract>

Department of Planetary Geodesy, Space Research Centre Polish Academy of Sciences, Warsaw, Poland

Department of Geodesy and Geodetic Astronomy, Faculty of Geodesy and Cartography, Warsaw University of Technology, Warsaw, Poland

Testing impact of the strategy of VLBI data analysis on the estimation of Earth Orientation Parameters and station coordinates

<abstract xmlns="http://www.w3.org/1999/xhtml"> Optimal design of geodetic network is a basic subject of many engineering projects. An observation plan is a concluding part of the process. Any particular observation within the network has through adjustment a different contribution and impact on values and accuracy characteristics of unknowns. The problem of optimal design can be solved by means of computer simulation. This paper presents a new method of simulation based on sequential estimation of individual observations in a step-by-step manner, by means of the so-called filtering equations. The algorithm aims at satisfying different criteria of accuracy according to various interpretations of the covariance matrix. Apart of them, the optimization criterion is also amount of effort, defined as the minimum number of observations required.A numerical example of a 2-D network is illustrated to view the effectiveness of presented method. The results show decrease of the number of observations by 66% with respect to the not optimized observation plan, which still satisfy the assumed accuracy.</abstract>

Faculty of Civil Engineering and Geodesy, Military University of Technology Kaliskiego St. 2, 00-908, Warsaw, Poland

University of Life Science in Lublin, Department of Environmental Engineering and Geodesy, kr. St. Leszczyńskiego St. 7, 20-069 Lublin, Poland

Optimization of observation plan based on the stochastic characteristics of the geodetic network

<abstract xmlns="http://www.w3.org/1999/xhtml"> The field of processing information provided by measurement results is one of the most important components of geodetic technologies. The dynamic development of this field improves classic algorithms for numerical calculations in the aspect of analytical solutions that are difficult to achieve. Algorithms based on artificial intelligence in the form of artificial neural networks, including the topology of connections between neurons have become an important instrument connected to the problem of processing and modelling processes. This concept results from the integration of neural networks and parameter optimization methods and makes it possible to avoid the necessity to arbitrarily define the structure of a network. This kind of extension of the training process is exemplified by the algorithm called the Group Method of Data Handling (GMDH), which belongs to the class of evolutionary algorithms. The article presents a GMDH type network, used for modelling deformations of the geometrical axis of a steel chimney during its operation. </abstract>

Elements of an algorithm for optimizing a parameter-structural neural network

<abstract xmlns="http://www.w3.org/1999/xhtml"> Presented paper is dedicated to problems of deformation of the Earth's crust as a response to the surface loading caused by continental waters. The aim of this study was to specify areas particularly vulnerable to studied deformation and to compare calculated and observed displacements. Information of the continental water volume was taken from the WaterGAP Global Hydrological Model. Calculated values of the deformations were verified with the results obtained with programs SPOTL and grat. Vertical deformations were almost 10 times higher than the deformation in the horizontal plane, for which reason later part of the paper focuses on the former. In order to check agreement of the calculated and observed deformation 23 stations of International GNSS Service (IGS) were selected and divided into three groups (inland, near the shoreline and islands). Before comparison outliers and discontinuities were removed from GNSS observations. Modelled and observed signals were centred. The analysed time series of the vertical displacements showed that only for the inland stations it is possible to effectively remove displacements caused by mass transfer in the hydrosphere. For stations located in the coastal regions or islands, it is necessary to consider additional movement effects resulting from indirect ocean tidal loading or atmosphere loading.</abstract>

Assessment of continental hydrosphere loading using GNSS measurements

<abstract xmlns="http://www.w3.org/1999/xhtml"> The paper integrates some earlier and the recent findings of the author in the area of network internal reliability and presents a consistent system of concepts in this respect. The concepts of outlier detection and outlier identification linked directly with the global model test and the outlier tests respectively, are shown as a basis for the concepts such as outlier detectability and outlier identifiability. Also, a four level classification of gross errors expressed in a form of a tree-diagram is presented including perceptible and imperceptible errors, detectable and undetectable errors and identifiable and unidentifiable errors. Their properties are given mainly in a descriptive way, deliberately limiting rigorous mathematical formulas to a necessary minimum. Understanding of different types of gross errors is useful in analyzing the results of the outlier detection and identification procedures as well as in designing the networks to make them duly robust to observation gross errors. It is of special importance for engineering surveys where quite often low-redundancy networks are used. Main objective of the paper is to demonstrate a clear and consistent system of basic concepts related to network internal reliability.</abstract>

Illustrative presentation of some basic concepts of network internal reliability with comments as regards engineering surveys

<abstract xmlns="http://www.w3.org/1999/xhtml"> This paper presents a concept for the identification of stable reference points used in horizontal control networks, which is based on the lengths of apparent displacement vectors and their mean errors. These vectors and their mean errors are obtained during the process of calculating displacements with free adjustment conditions. It will be shown that the influence of the apparent displacement vectors has a significant effect on the calculation of results. The identification of stable points, using the proposed method, is an integral part of the adjustment process and allows for the interrogation the influence of individual point inclusion or deletion from the reference database, on the values of displacements of controlled points. A detailed process of stable reference points identification is presented using the example of a linear-angular network for a barrage.</abstract>

A concept for the examination of reference points stability in horizontal control networks

<abstract xmlns="http://www.w3.org/1999/xhtml"> We compared the method of least squares (LS), Pope’s iterative data snooping (IDS) and Huber’s M-estimator (HU) in realistic leveling networks, for which the heights or the vertical displacements of points are known. The study was conducted using the Monte Carlo simulation, in which one repeatedly generates sets of observations related to the measurement data, then calculates values of the estimators and, finally, assesses it with respect to the real coordinates. To simulate outliers we used popular mixture models with two or more normal distributions. It is shown that for small, strong networks robust methods IDS and HU are more accurate than LS, but for large, weak networks occurring in practice there is no significant difference between the considered methods in the accuracy of the solution.</abstract>

Comparison of robust estimators for leveling networks in Monte Carlo simulations

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Reports on Geodesy and Geoinformatics

 Reports on Geodesy and Geoinformatics (formerly Reports on Geodesy) is recognized as a semi-annual scientific journal that has appeared since 1991. The volumes of this journal had been prepared and edited by the staff of the Institute of Geodesy and Geodetic Astronomy until 2008 and then during the reorganization of the Faculty of Geodesy and Cartography between years 2008-2011 the volumes were edited and printed by the scientists of the Department of Geodesy and Geodetic Astronomy of Warsaw University of Technology (WUT). Since 2012 the journal has been edited by the scientific staff of the Faculty of Geodesy and Cartography of WUT.  Each paper submitted for publishing in Reports on Geodesy and Geoinformatics is peer-reviewed. The list of our revisers contains more than 200 scientists both from Poland as well as from other countries. Our revisers are recognized specialists from different branches of geodesy and cartography. In some issues of Reports on Geodesy and Geoinformatics there are presented contents of papers announced at international conferences and such volumes may be recognized as the proceedings from these scientific meetings.  All papers published in Reports on Geodesy and Geoinformatics are available in an open access formula. All of them have been also distributed among over 110 libraries in Poland as well as foreign institutions and are considered to be very well acknowledged by the international geodetic community.  Peer-review. The journal uses single-blind peer review (the authors do not know the reviewers) to avoid bias. See more information &lt;Peer Review&gt;.  Journal policies. The journal provides its’ policies, which include detailed information about submission, editorial and publishing processes and guidelines for authors and reviewers. All parties are being introduced to their rights and responsibilities to ensure smooth and ethical publishing process. See more information &lt;Journal Policies&gt;  Fees and Charges. The journal operates as open access journal, the process is completely free of charges to both authors and readers. All publication fees are covered by Warsaw University of Technology.　  Publication schedule. The journal is semi-annual (2 Issues per year in June and December). All articles are published online under CC BY-NC-ND licence 4.0 within four weeks after acceptance as a continuous publication (Online first) to avoid any delays.　  Copyright. Individual articles are published Open Access under the Creative Commons Licence: CC BY-NC-ND 4.0, which permits non-commercial use, distribute, display and perform only original copies of the work in any medium, provided the original author and source are credited. Authors retain copyright in their articles, but grant RGG the right of the first publication. The journal is copyright RGG © Warsaw University of Technology (WUT), all rights reserved.   Aims and ScopeReports on Geodesy and Geoinformatics in keeping with tradition, is intent on presenting the whole of technological and scientific progress taking place in modern geodesy and cartography, where research and implementation of geoinformatic character play an exceptionally important role in accelerating the development of our discipline. It is for this reason that we have decided to expand the journal’s formula so as to encourage a broader group of scientists and specialists in the realms of geodesy, computer science, cartography, photogrammetry, remote sensing, geography, geology, and related sciences who are developing new methods and technologies of geovisualization and are involved in the modeling of space applying GIS technology to collaborate with us. At the same time, the journal’s profile shall maintain the importance of other theoretical, industrial, and development research in the areas of theoretical geodesy, geodetic astronomy, navigation, and studies on displacements and the classic problems facing geodesic surveying.  Journal PoliciesThe journal provides its’ policies, which include detailed information about submission, editorial and publishing processes and guidelines for authors and reviewers. All parties are being introduced with their rights and responsibilities to ensure smooth and ethical publishing process. Visit following subsections for more details on each policy:    Publication Ethics and Publication Malpractice Statement  Open Access  Privacy Statement   Reports on Geodesy and Geoinformatics (formerly Reports on Geodesy) in keeping with tradition, is intent on presenting the whole of technological and scientific progress taking place in modern geodesy and cartography, where research and implementation of geoinformatic character play an exceptionally important role in accelerating the development of our discipline. It is for this reason that we have decided to expand the journal's formula so as to encourage a broader group of scientists and specialists in the realms of geodesy, computer science, cartography, photogrammetry, remote sensing, geography, geology, and related sciences who are developing new methods and technologies of geovisualization and are involved in the modeling of space applying GIS technology to collaborate with us. At the same time, the journal's profile shall maintain the importance of other theoretical, industrial, and development research in the areas of theoretical geodesy, geodetic astronomy, navigation, and studies on displacements and the classic problems facing geodesic surveying.Internet access to complete articles in an "open access" formula will significantly facilitate use by those who are interested as well as expand the circle of readers.  Archiving  Sciendo archives the contents of this journal in Portico - digital long-term preservation service of scholarly books, journals and collections.  Plagiarism Policy  The editorial board is participating in a growing community of Similarity Check System's users in order to ensure that the content published is original and trustworthy. Similarity Check is a medium that allows for comprehensive manuscripts screening, aimed to eliminate plagiarism and provide a high standard and quality peer-review process. 