Geodetic Control Network Research Articles

Mobile Laser Scanning Systems for Measuring the Clearance Gauge of Railways: State of Play, Testing and Outlook.

The paper contains a survey of mobile scanning systems for measuring the railway clearance gauge. The research was completed as part of the project carried out for the PKP (PKP Polish Railway Lines S.A., Warsaw, Poland) in 2011–2013. The authors conducted experiments, including a search for the latest solutions relating to mobile measurement systems that meet the basic requirement. At the very least, these solutions needed to be accurate and have the ability for quick retrieval of data. In the paper, specifications and the characteristics of the component devices of the scanning systems are described. Based on experiments, the authors did some examination of the selected mobile systems to be applied for measuring the clearance gauge. The Riegl (VMX-250) and Z+F (Zoller + Fröhlich) Solution were tested. Additional test measurements were carried out within a 30-kilometer section of the Warsaw-Kraków route. These measurements were designed so as to provide various elements of the railway infrastructure, the track geometry and the installed geodetic control network. This ultimately made it possible to reduce the time for the preparation of geodetic reference measurements for the testing of the accuracy of the selected systems. Reference measurements included the use of the polar method to select profiles perpendicular to the axis of the track. In addition, the coordinates selected were well defined as measuring points of the objects of the infrastructure of the clearance gauge. All of the tested systems meet the accuracy requirements initially established (within the range of 2 cm as required by the PKP). The tested systems have shown their advantages and disadvantages.

Application of Monte Carlo method to statistical testing in deformation analysis based on robust M-estimation

In deformation analysis of geodetic control networks, it is important to know whether the estimated displacement value of a given point is the effect of displacement or only the effect of random measurement errors. The F-test of statistical significance is used to answer this question. This test is applied both in conventional deformation analysis (CDA) based on least square (LS) estimation and in deformation analysis based on robust M-estimation. Unfortunately, the F-test is strongly flawed in the latter case. As a consequence, its results are significantly different here than assumed/expected. This paper analyses how flawed the F-test is and proposes a new solution. First, the algorithm of the global and local F-tests was derived. It was then demonstrated that for deformation analysis based on robust M-estimation, this algorithm has theoretical flaws. Next, it was shown how these problems can be solved numerically. The basis of the solutions proposed involves the use of stochastic simulations and, more specifically, the Monte Carlo (MC) method. Moreover, it was noted that other statistical test problems which also occur in deformation analysis based on robust M-estimation can be solved using present-day computers. The numerical approach can be a good support here in the selection of the proper significance level as well as in the correct performance of the test sensitivity analysis. All theoretical discussions were verified on an example simulated control network.

Datum maintenance of the main Egyptian geodetic control networks by utilizing Precise Point Positioning “PPP” technique

A geodetic control network is the wire-frame or the skeleton on which continuous and consistent mapping, Geographic Information Systems (GIS), and surveys are based. Traditionally, geodetic control points are established as permanent physical monuments placed in the ground and precisely marked, located, and documented. With the development of satellite surveying methods and their availability and high degree of accuracy, a geodetic control network could be established by using GNSS and referred to an international terrestrial reference frame used as a three-dimensional geocentric reference system for a country. Based on this concept, in 1992, the Egypt Survey Authority (ESA) established two networks, namely High Accuracy Reference Network (HARN) and the National Agricultural Cadastral Network (NACN). To transfer the International Terrestrial Reference Frame to the HARN, the HARN was connected with four IGS stations. The processing results were 1:10,000,000 (Order A) for HARN and 1:1,000,000 (Order B) for NACN relative network accuracy standard between stations defined in ITRF1994 Epoch1996. Since 1996, ESA did not perform any updating or maintaining works for these networks.To see how non-performing maintenance degrading the values of the HARN and NACN, the available HARN and NACN stations in the Nile Delta were observed. The Processing of the tested part was done by CSRS-PPP Service based on utilizing Precise Point Positioning “PPP” and Trimble Business Center “TBC”. The study shows the feasibility of Precise Point Positioning in updating the absolute positioning of the HARN network and its role in updating the reference frame (ITRF). The study also confirmed the necessity of the absent role of datum maintenance of Egypt networks.

Investigating efficacy of robust M-estimation of deformation from observation differences

Generalized robust M-estimation of deformation from observation differences (GREDOD) is a robust method for deformation analysis of geodetic control networks. This method has been developed based on the well known robust Iterative weighted similarity transformation (IWST) method. Hence, in the GREDOD method, as in the IWST method, the L1-norm weight function is the weight function for the displacement vector and the displacement vector components are the weight function variables. The L1-norm weight function for variables in the form of the displacement vector components is the simplest and most natural solution, but it is not known whether this is the most efficacious solution for the GREDOD method. To assess this, the current study used different robust weight functions which were tested for variables in the widely used form of the displacement vector components and for variables in the form of displacement lengths. All solutions were tested on the basis of the simulated two-epoch observations of the absolute control network of the Montsalvens dam in Switzerland. The efficacy measure for individual solutions was the mean success rate (MSR).

The current state of the creation and modernization of national geodetic and cartographic resources in Poland

AbstractAll official data are currently integrated and harmonized in a spatial reference system. This paper outlines a national geodetic and cartographic resources in Poland. The national geodetic and cartographic resources are an important part of the spatial information infrastructure in the European Community. They also provide reference data for other resources of Spatial Data Infrastructure (SDI), including: main and detailed geodetic control networks, base maps, land and buildings registries, geodetic registries of utilities and topographic maps. This paper presents methods of producing digital map data and technical standards for field surveys, and in addition paper also presents some aspects of building Global and Regional SDI.

Обеспечение единого координатного пространства: результаты апробации методики создания ВОГС

The article explains practical aspects of the departmental geodetic control network segment development on the part of the M-4 “Don” highway. It describes procedure and results of the departmental geodetic control network stations association with world, national and local coordinate systems. It also shows a comparative analysis of the elevations transfer precision in the 1977 Baltic height system with GNSS-methods and geometrical levelling.

Assessment of Vertical Deformation of the Atatürk Dam Using Geodetic Observations

AbstractThe Ataturk Dam in Turkey, constructed on the Firat River, is one of the world’s largest rockfill embankment dams. It was built to harvest and conserve water and to serve crucial agricultural, social-economic, recreational, and other activities in the Harran region. In this study, geodetic techniques were exploited to assess possible deformations of the embankment structure and add insight on critical dam safety. The geodetic approach included differential, trigonometric, and global positioning system (GPS) leveling observation campaigns over a period of 6.5 years from May 2006 through November 2012. The geodetic control network included 32 reference points and approximately 200 object points located on the surface of the embankment structure. The primary object points were stable concrete platforms embedded on the compacted rock surface, whereas the secondary object points were mounted directly to the compacted rock. All object points were equipped with forced centering mechanisms to support eith...

Инновационный подход к построению опорных геодезических сетей линейных объектов

Abstract: An innovative concept of constructing geodetic control networks at the stage of engineering surveys for the design and construction of linear facilities large extent on the widespread use of continuously operating reference base stations is outlined. The coordinates of them are defined in the same for the whole linear object of the coordinate space. To minimize the distortion of angles and distances in the depiction of the earth’s surface on topographic plans rectangular coordinate system on a plane oblique cylindrical Mercator projection in the version by Khotin is offered. The Central line of the projection is proposed to set so that the distortion of the scale along the route was presented in small quantities which in practice can be neglected. The heights of the points are requested to be obtained from the conversion of the spatial geodetic coordinates based on local models of exactly quasigeoid heights. The technique of constructing a local model of the anomalies of the altitudes along the route of the object was shown.

Determination Of Horizontal Geodetic Control Networks For Engineering Objects Using Optoelectronic Techniques

Abstract The correctness of the geodetic service of an engineering object not seldom requires designing, alignment or renewing of geodetic situational control points. Building robots often cause that fixed situational control points are partly or completely inaccessible. For setting the position of these control points, there is worked out the methodology using the optoelectronic method. The prepared set of tools realizes the method’s assumptions and enables to determine the sides and control points based on the set of laser planes. In this article there is presented the innovative set of geodetic equipment for fixing horizontal control points. The presented set has been experimentally tested under laboratory conditions taking its functionality, operation range and applied accuracy into account. The measurement accuracy of the set of tools, resulting from identification of the energetic centres of laser planes’ edges, visualizing the sides of geodetic control networks, is within the range of ±0.02mm - ±0.05mm. There were also discussed exemplary versions of shapes and structures of horizontal geodetic control networks (regular and irregular), which are possible to be fixed with the use of the constructed set of tools.

Robust M-Estimation in Analysis of Control Network Deformations: Classical and New Method

AbstractRobust M-estimation is very useful in the geometric deformation analysis of geodetic control networks, especially in the analysis of single-point displacements in these networks. In fact, a robust M-estimation allows one to identify the datum that resists individual displaced points. This paper describes and tests two competing methods for displacement analysis based on robust M-estimation. Both methods accept relative and absolute control networks. The first method is the classical robust method, in which the displacement vector is determined from differences in adjusted coordinates. The second method is a new and alternative robust method, in which the displacement vector is determined from differences in unadjusted observations. The proposed method was conventionally called Generalized Robust Estimation of Deformation from Observation Differences. Classical and proposed robust methods were tested on the basis of the simulated two-epoch observations of the absolute control network of the Montsal...

Landform Monitoring and Warning Framework Based on Time Series Modeling of Topographic Databases

Global Positioning System (GPS) and geodetic control networks are used today for analyzing and monitoring time-dependent crustal deformations, providing a series of accurate positional measurements to deliver information on positional changes and deformations that have occurred. Still, such networks present a low-resolution dispersal of positional measures, and do not take into account various physical constraints that affect the terrain’s seismic behavior. An alternative form of spatio-temporal infrastructure that is feasible and practical to establish might involve the use of Digital Terrain Model (DTM) databases. These databases use higher positional resolutions, and are exhibiting an increasing level of positional and height accuracy. Still, when comparing temporal DTMs, the separation of actual physical phenomena from data-related ambiguities is essential in the framework of spatio-temporal analysis. This paper proposes the use of a hierarchical co-modeling of different DTM databases for the task of landform monitoring. Analyses showed promising results, pointing to the feasibility of the proposed methodology in monitoring and quantifying topographic-related spatio-temporal phenomena, such as landslides and change detection, thus facilitating a reliable and precise landform monitoring and warning framework for geomorphodynamic analyses.

Field tests of L1 phase centre variation models of surveying-grade GPS antennas

GNSS antenna electrical phase center variability is a source of errors in precise geodetic measurements, particularly in reference frame maintenance, satellite precise levelling, deformation monitoring, the establishment of geodetic control networks, geodynamic research, etc. It has a considerable influence on the precision and accuracy of the resulting coordinates. Previous research shows that changing the antenna on the monitored point often results in a considerable bias in the derived height coordinate component. In theory, if electrical phase center is sufficiently modeled, antenna changes should have negligible effect on coordinates. We present the analysis of the influence of the GPS antenna models on the resulting marker position. Numerical tests are based on field measurements. The GPS data collected at the test baseline were processed using Bernese GPS Software Version 5.0. The research shows that the IGS and NGS phase center variation models for some types of the surveying (rover) antennas are still imperfect and are contaminated by constant errors, which may exceed even ± 5 mm for horizontal coordinates components and ± 25 mm for vertical ones.

Estimation of an Effective Young’s Modulus of Elasticity in the Locality of the Gabčíkovo Hydrology Power Plant by Geometric Leveling

Abstract The Gabčíkovo hydroelectric power plant is located in a complicated geological environment (gravel sub-soil and a high groundwater level). Excavation work started after the withdrawal of water in the autumn of 1984 and lasted until the autumn of 1986. A basic geodetic control network with a special monument was founded before the excavation work began. This network served for the setting-out of the hydroelectric power plant as well as for the control of the excavation work. The repeated geodetic control measurements have been evaluated and presented at many seminars and conferences. Monitoring the horizontal and vertical stability of the geodetic control network during the general site excavation showed significant horizontal and vertical deformations. The paper is focused on an estimation of an effective Young's modulus of elasticity in the area studied.

Determination of geodetic control network points using GPS technology for the purpose of monitoring power lines in difficult terrain conditions

Summary The present work discusses the issue of determining geodetic control network in order to monitor the condition of power lines. The problem was presented using the example of the physical survey of an actual infrastructure – a high voltage power line. Difficult terrain conditions constituted a significant factor for determining an appropriate measurement method. The measurement itself was conducted using two methods, independently of one another: the classical traverse method, and the RTK (Real Time Kinematic) GPS method. The following criteria were assumed for the purpose of the comparison: measurement effectiveness and the accuracy of the calculation result. Basic monitoring procedures of power lines were also presented, implemented based on the measurement network established beforehand.

Обеспечение единого координатного пространства: привязка к государственной системе высот

The article provides the ways of solving the problem of achieving accuracy in defining of altitudinal component of departmental geodetic control network on the 10 mm level of the 1977 Baltic height system. Particular attention is paid to the aspects related to the association of departmental geodetic control network stations with the 1977 Baltic height system using global navigation satellite system.

Study on spatial distribution of horizontal geodetic control points in rural areas

The paper presents the results of research concerning the analysis of spatial distribution of detailed geodetic control points in rural areas in Poland. The analysis takes into consideration the relations between the number of geodetic control points and land cover type (built-up, agricultural, and forest) as well as the effective legal regulations in Poland with regard to the issues. The analysis results were referred to geodetic sections classified by the k-means method with respect to the number of the control points and the built-up, agricultural and forest areas. The research indicates that the number of the geodetic control points in an area depends to the extent of 35 % on the type of land cover (building, agricultural and forest land). Having this in mind, the authors recommend taking the land cover into consideration already in the phase of designing a geodetic control network.

Accuracy standards of tying the horizontal and vertical control network to the National Geodetic Control Network.

To adjust the survey results of multi‐row networks the Gauss–Markov model can be used, including accuracy weight matrix for the values observed, as well as in‐ cluding the apparent observational equations for the coordinates of tie points. To the apparent observational equations the relevant accuracy weights are assigned for the analysed coordinate points or their covariance matrices. Many authors of scientific papers use for that purpose the sequential adjustment of measurement results, i.e. the adjustment carried out in a few stages. By foreign authors, there are the works of Baardy [2], Teunissen [14] and Rao [13]. By domestic authors, there are the pa‐ pers of Adamczewski [1], Baran [3], Gaździcki [7], Kadaj [8], Wiśniewski [15] and Kaminski [9]. Many computer programmes, e.g. GOENET [8], use this procedure to adjust measurement results of the multirow control networks. The issue of the estimation of the horizontal and vertical control point coordi‐ nates in tying to national geodetic control networks is similar to multirow networks adjustment but specific allocation of these networks set down different conditions of tying them to national geodetic control networks. This problem, in relation to determination of point displacement, was worked on in Canada by Chrzanowski [4] and in Germany by Pelzer [10]. Similar deliberations were made nationally by Cza‐ ja [6] and Proszynski and Kwaśniak [12]. The deliberations included in this pub‐ lication will only be referred to three thematically nearest positions, i.e. Czaja [5], Proszynski [11] and Wiśniewski [16]. In paper [5] the author proposes to include the observations of connecting national geodetic control network points to the adjuste‐ ment of horizontal and vertical control network. For the coordinates of national ge‐ odetic control points the author proposes to juxtapose the pseudo‐observation equa‐ tions including their ccovariance matrices. Proszynski [11] in his paper presents the method of tying the horizontal and vertical control networks to the national geodetic

Sentinel Site Development of a Major Salt Marsh System in the Mid-Atlantic Region (USA)

The Tuckerton Peninsula, a large expanse (~2000 ha) of highly inundated Spartina alterniflora salt marsh habitat, forms one of the most extensive coastal wetland systems in New Jersey (USA). It is projected to be among the first salt marsh systems in New Jersey to be lost by rising sea level driven by climate change. The changes that occur in the demographic, ecologic, and ecogeomorphic characteristics of the salt marsh habitat at this location will be vital to understanding future habitat change in coastal wetlands in the Mid-Atlantic region. As a consequence, the Tuckerton Peninsula salt marsh system is designated as a sentinel site of the Jacques Cousteau National Estuarine Research Reserve (JCNERR) for the detection, monitoring, and assessment of climate change effects, most notably sea-level rise and inundation. Development of the Tuckerton Peninsula as a sentinel site requires a high accuracy local geodetic control network to connect existing water quality monitoring stations, vegetation transects and monitoring surface elevation tables, ground water wells, and digital elevation models on the same vertical datum. The integration of these monitoring infrastructure components is crucial to effective operation of the sentinel site. It will enable the collection of essential data to assess rates of marsh migration and upland transgression, as well as delineate key natural and anthropogenic drivers influencing habitat condition and change. The JCNERR sentinel site designation supports the National Oceanic and Atmospheric Administration’s long-term goal of assessing coastal vulnerability in the USA to climate change and generating data useful for forging climate adaptation and mitigation initiatives for coastal communities. Habitat and vertical control data collected at this sentinel site will be made available to decision makers across the nation and will enable them to determine how the loss of critical salt marsh habitat will affect coastal communities, their adaptation to future habitat loss, and their development of mitigation plans to address impacts and enhance resiliency.

Assessment of PPP for establishment of CORS network for municipal surveying in Middle East

Nowadays many Continuously Operating Reference Stations (CORS) network were established in the Middle East to improve different municipal surveying. Establishing such geodetic control networks can be a costly business where multiple stations should be occupied simultaneously and post-processed with scientific software. Recently, precise point positioning (PPP) has attracted wide interest because it provides an alternative to precise relative processing due to its potential as a reliable absolute positioning technique operational simplicity. In comparison with common relative GPS techniques, the costs are reduced; because no base stations and no simultaneous observations are necessary. This research investigates the capability of PPP approach to be a low cost alternative to the conventional positioning methods used in coordinates determination of geodetic networks. The GPS data used during setting up Jeddah municipality network were originally processed by Bernese software version 5.0. That GPS data were processed again using PPP approach and comparable investigation was carried out between the coordinates obtained from Bernese software and CSRS-PPP software. The results showed that overall CSRS-PPP solutions agreed with the Bernese solutions, where the Root Mean Square of the difference between the two solutions reaches 2·6 mm in Easting, 2·5 mm in Northing, and 10 mm in Height. The derived centimetre accuracy from PPP approach which is suitable for municipal surveying confirmed that it can be used for establishment of CORS networks.

Verification of applicability of the Trimble RTX satellite technology with xFill function in establishing surveying control networks

Abstract The paper presents the results of real time measurements of test geodetic control network points using the RTK GPS and RTX Extended technologies. The Trimble RTX technology uses the xFill function, which enables real measurements without the need for constant connection with the ASG EUPOS system reference stations network. Comparative analyses of the results of measurements using the methods were performed and they were compared with the test control network data assumed to be error-free. Although the Trimble RTX technology is an innovative measurement method which is rarely used now, the possibilities it provides in surveying works, including building geodetic control networks, are satisfactory and it will certainly contribute to improving the organisation of surveying works.