Showing papers in "Journal of Applied Geodesy in 2010"
TL;DR: In this paper, the principles of the microwave interferometer IBIS are presented, as well as its advantages and disadvantages compared to common monitoring techniques, and three applications are presented: the use of IBIS-S for dynamic monitoring of a chimney, the long-term operation of IBMIS-L as part of a “Volcano Fast Response System” (VFRS) on an active volcano.
Abstract: Abstract One fundamental component of early warning systems for natural hazards is displacement monitoring. Spaceborne SAR Interferometry has proven to be a powerful remote sensing tool for this task. Lately new ground-based SAR instruments are available. Their application field is wide and they combine high resolution and accuracy with the classical benefits of remote sensing techniques. Here, the principles of the microwave interferometer IBIS are presented, as well as its advantages and disadvantages compared to common monitoring techniques. IBIS can be operated in two modes: IBIS-S is a microwave interferometer capable of high frequency displacement monitoring of buildings and structures (up to 200 Hz); IBIS-L is a ground-based SAR for long-term displacement monitoring of buildings and natural phenomena as landslides, glaciers, etc. Exemplary three applications are presented: the use of IBIS-S for dynamic monitoring of a chimney; the use of IBIS-L for displacement monitoring in an active quarry and the long-term operation of IBIS-L as part of a “Volcano Fast Response System” (VFRS) on an active volcano.
88 citations
TL;DR: In this article, a 3D laser scanner operating in a 2D line-scan mode from various different runs and scan directions is used for determining the angular alignment between inertial measurement unit and laser scanner.
Abstract: Abstract Mobile laser scanning (MLS) is the latest approach towards fast and cost-efficient acquisition of 3-dimensional spatial data. Accurately evaluating the boresight alignment in MLS systems is an obvious necessity. However, recent systems available on the market may lack of suitable and efficient practical workflows on how to perform this calibration. This paper discusses an innovative method for accurately determining the boresight alignment of MLS systems by employing 3D laser scanners. Scanning objects using a 3D laser scanner operating in a 2D line-scan mode from various different runs and scan directions provides valuable scan data for determining the angular alignment between inertial measurement unit and laser scanner. Field data is presented demonstrating the final accuracy of the calibration and the high quality of the point cloud acquired during an MLS campaign.
68 citations
TL;DR: In this article, the authors developed and tested three innovative measurement systems for the detection of subsurface displacements in boreholes and reflectorless video tacheometry (VTPS) and a low cost GNSS sensor component for the deterministic detection of 3D surface movements.
Abstract: Mainly in the context of global climate change the awareness of landslide hazards has risen considerably in most mountainous regions world- wide in the last years. National and regional hazard mapping programs were set up in many countries and most of the potentially endangered sites have been identified. Although exclusive geodetic and geotechnical instrumentation is available today, due to some economical reasons only few of the identi- fied potentially risky landslides are monitored per- manently. The intention of the alpEWAS research project is to develop and to test new techniques suit- able for e‰cient and cost-eective landslide moni- toring. These techniques are combined in a geo sen- sor network with an enclosed geo data base and a developed software package to use the whole system for stakeholder information and early warning pur- poses. The core of the project is the development and testing of the three innovative measurement systems time domain reflectometry (TDR) for the detection of subsurface displacements in boreholes and reflectorless video tacheometry (VTPS) and a low cost GNSS sensor component for the determi- nation of 3D surface movements. Essential experi- ences obtained during the project will be described.
35 citations
TL;DR: In this paper, the authors assess the dynamic measurement quality and reliability of inclinometers for building monitoring applications, and discuss the strengths and weaknesses of GPS vis-a-vis the use of inclina- tion sensors for monitoring the dynamic response of tall buildings under wind load.
Abstract: It is necessary to use dierent sensors in an integrated manner - GPS, accelerometer, inclina- tion sensor and so on - in order to monitor and identify static, quasi-static and resonant response of tall buildings subjected to wind loading. There are some dierences among these sensors with respect to data sampling rate, data quality, and their mea- surement accuracy. Therefore, using dierent sen- sors together for a monitoring project is important because of the complementary nature of each sen- sor. In this study, the behaviour of a tall reinforced concrete building (30 stories high) under wind load has been monitored using GPS and inclination sen- sors. This paper assesses the dynamic measurement quality and reliability of inclinometers for building monitoring applications, and discusses the strengths and weaknesses of GPS vis-a-vis the use of inclina- tion sensors for monitoring the dynamic response of tall buildings under wind load. Data collected by these sensors have been analysed in the time and frequency domains. It was found that GPS observa- tions were distorted by multipath caused by a re- flecting surface on top of the building. From the analyses in the frequency domain, the 1 st mode nat- ural frequencies of the building determined from both sensors agree very well with each other. The discrepancy of this measured 1 st mode natural fre- quency compared to that derived from FEM (Finite Element Model) prediction is 7%.
32 citations
TL;DR: In this paper, coordinate transformations between ITRF and the Geocentric Datum of Australia 1994 (GDA94) have been reviewed, improved and extended for many applica- tions, including novel coordinate transformation approaches and justifications for the modernisation of GDA.
Abstract: The Geocentric Datum of Australia 1994 (GDA94) is a static coordinate datum realised with respect to the International Terrestrial Reference Frame (ITRF) at the reference epoch of 1 January 1994. At this time GDA94 and ITRF were coinci- dent, however, as a consequence of the tectonic mo- tion of the Australian Plate, ongoing refinement of the ITRF and crustal deformation, the two reference frames have diverged and the absolute di¤erence between them is now approximately 1 m. Conse- quently, precise coordinate transformations between ITRF and GDA94 are required for many applica- tions, and in this study these transformations are reviewed, improved and extended. New transforma- tion parameters between ITRF and GDA94 are computed, including the specific ITRF realisations of ITRF1996, ITRF1997, ITRF2000, ITRF2005 and ITRF2008. The two most recent ITRF realisa- tions, ITRF2005 and ITRF2008, after transforma- tion have a root-mean-square di¤erence of less than 10 and 30 mm in the horizontal and vertical compo- nents, respectively, with respect to GDA94 at the Australian Fiducial Network (AFN) stations. How- ever, the magnitude of some residuals exceed 15 and 60 mm in the horizontal and vertical components, respectively, which reflects the accuracy limit of GDA94. Finally, the implications and future strat- egies for managing the di¤erences between GDA94 and ITRF are discussed, including novel coordinate transformation approaches and justifications for the modernisation of GDA.
26 citations
TL;DR: In this article, three hydrostatic displacement monitoring system applications in Switzerland are discussed; the first concerns experience gained monitoring the foundation of the Albigna dam, the second relating to the underground stability of the Swiss Light Source synchrotron and the third concerning the deformation of a bridge near the city of Lucerne.
Abstract: SUMMARY Three hydrostatic displacement monitoring system applications in Switzerland are discussed; the first concerns experience gained monitoring the foundation of the Albigna dam, the second relating to the underground stability of the Swiss Light Source synchrotron and the third concerning the deformation of a bridge near the city of Lucerne. Two different principles were applied, the Hydrostatic Leveling System (HLS) using the “half-filled pipe principle” which was developed for the Paul Scherrer Institute (PSI) and the Large Area Settlement System (LAS) using the “differential pressure principle”. With both principles deformations down to ground deformations induced by tidal forces can be seen. However, high accuracy of single sensors is not sufficient. A well-considered configuration of the complete system is equally important. On the other hand there are also limits given by the feasible installation or by the environmental conditions. Such an example is shown in the measurement task of the bridge, where the acceleration along the bridge due to the pass over of heavy trucks is limiting the feasibility of hydrostatic leveling measurements.
23 citations
TL;DR: In this article, an adaptive extended Kalman filter (AEKF) approach for geo-referencing tasks for a multi-sensor system (MSS) is described, which is a sensor fusion of a phase measuring terrestrial laser scanner (TLS) with navigation sensors such as Global Navigation Satellite System (GNSS) equipment and inclinometers.
Abstract: Abstract This paper describes an adaptive extended Kalman filter (AEKF) approach for geo-referencing tasks for a multi-sensor system (MSS). The MSS is a sensor fusion of a phase-measuring terrestrial laser scanner (TLS) with navigation sensors such as Global Navigation Satellite System (GNSS) equipment and inclinometers. The position and orientation of the MSS are the main parameters which are constant on a station and will be derived by a Kalman filtering process. Hence, the orientation of a TLS/MSS can be done without any demand for other artificial targets in the scanning area. However, using inclinometer measurements the spatial rotation angles about the X- and Y-axis of the fixed MSS station can be estimated by the AEKF. This makes it possible to determine all six degrees of freedom of the transformation from a sensor-defined to a global coordinate system. The paper gives a detailed discussion of the strategy used for the direct geo-referencing. The AEKF for the transformation parameters estimation is presented with focus on the modelling of the MSS motion. The usefulness of the suggested approach will be demonstrated using practical investigations.
22 citations
TL;DR: In this article, a case study on the attempt of integrating GPS with Ubisense Real-time Location System (RTLS) for resources man- agement in an underground railway construction site is discussed.
Abstract: The application of integrated satellite and modern wireless positioning technologies for ubiquitous real-time resources management in large scale civil engineering projects can greatly optimize the time and cost in the construction process, and is now the trend for modern construction project man- agement. As the outdoor conditions of most civil construction sites are open to sky, satellite position- ing with the popularly used Global Positioning System (GPS) has been proved to be very e‰cient and eective. However, the condition in indoor and underground construction site is very complicated due to the fact that dierent construction activities would be carried out in dierent congested areas, involving heavy construction plant, equipment, pro- fessionals and technical personnel. Nowadays dier- ent emerging technologies such as Wi-Fi and ZigBee can be adopted for position and tracking in indoor environments. Nevertheless, under the very com- plicated construction site conditions these technolo- gies may fail due to movement of human resources and construction plant, variation of metrological conditions, and serious multipath eects of signals. It is considered that Ultra Wide Band (UWB) tech- nology is more suitable for indoor construction site environments. In this paper, a case study on the attempt of integrating GPS with Ubisense Real- time Location System (RTLS) for resources man- agement in an underground railway construction site is discussed. Laboratory and field tests have shown that the RTLS can provide better resources management capability in terms of positioning accuracy and stability than Wi-Fi and ZigBee tech- nologies under complicated construction environ- ments. The test results show that the system can normally achieve better than 15 cm accuracy, and better than 1 m under adverse geometrical site condition. However, the high instrumental set up cost and the requirement for high quality data trans- mission cable for high precision time synchroni- zation between sensors may deter wide application of similar system for resources management in con- struction sites.
16 citations
TL;DR: In this article, the sensitivity of a geodetic monitoring network is defined as its capacity to detect and measure movements and deformations in the area covered by the network, and it is shown how the sensitivity is strongly influenced by the geometry of the network points.
Abstract: The sensitivity of a geodetic monitoring network is defined as its capacity to detect and measure movements and deformations in the area covered by the network. This paper attempts to study the e¤ects of datum definition on the sensitivity of geodetic networks. Principles from continuum mechanics are used to analyze the datum definitions required for a sensitive network, and it is shown how the sensitivity of a monitoring network is strongly influenced by the geometry of the network points. This paper presents a new perspective and describes relevant parameters that enable defining and quantifying the influence of the datum on the sensitivity of geodetic networks. Following an introduction of the concept of geodetic networks sensitivity and a development of theoretical tools, the paper presents the sensitivity analysis of a group of points in the network and the influence of datum definition on the sensitivity of geodetic monitoring networks. Two main conclusions arise in the paper, the sensitivity is invariant to the datum definition and the geometric location of the network points is extremely important to the network sensitivity, as different point distributions lead to di¤erent levels of sensitivity.
14 citations
TL;DR: In this article, the first deformation trial using Locata technology carried out at Tumut Pond Dam, in the state of New South Wales, Australia was run for 22 hours and yielded millimetre-level precision for horizontal positions, and centimetrelevel vertical precision for all observed epochs.
Abstract: Abstract Locata Corporation's positioning technology “Locata” is a terrestrial-based RF-ranging technology that provides high accuracy position solutions using a network (LocataNet) of time synchronised pseudolite-like transceivers (LocataLites). This technology provides centimetre level accurate position solutions for static positioning using carrier phase measurement data which provides an advantage over other technology for monitoring structural movement in many applications. The Locata network can be deployed in such a configuration around a structure that optimal network geometry could be ensured despite site constraints. This paper describes the first deformation trial using Locata technology carried out at Tumut Pond Dam, in the state of New South Wales, Australia. This trial was run for 22 hours and yielded millimetre-level precision for horizontal positions, and centimetre-level vertical precision for all observed epochs. The accuracy of the coordinate solutions was at the few millimetre level with standard deviations of 2.5 mm, 2.1 mm and 18 mm for the east, north and height components respectively. The position solutions were generated by an iterative least squares estimation process of Locata carrier phase observations per epoch. Then mean of sixty seconds coordinate solutions was used as input for a Kalman filter. Standard deformation detection methods were applied. No significant displacement was observed during this trial.
12 citations
TL;DR: In this article, the authors present Locata performance indoors, its capacity and mitigation methods, which mitigates the need for a clear view of the sky and provides system integrity control, which is a possible solution for the deployment of a sup- porting system, such as Locata.
Abstract: GNSS has become one of the most wide- spread measurement technologies, allowing cm-level positioning accuracy using RTK or Network RTK. Unfortunately, the system’s major drawbacks are the requirement for a clear view of the sky and accu- racy dependent on the geometric distribution of the satellites, not only varying throughout the day but also prone to location specific problems. With wide- spread utilisation of GNSS for monitoring of man- made structures and other civil engineering tasks, such shortcomings can be critical.
One of possible solution is the deployment of a sup- porting system, such as Locata – a terrestrial posi- tioning technology, which mitigates the need for a clear view of the sky and provides system integrity control.
This paper, part of the proposed integration feasibil- ity study, presents Locata performance indoors, its capacity and mitigation methods.
TL;DR: 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 is illustrated.
Abstract: Abstract 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 three examples, namely, a geo-risk assessment system supported by a knowledge-base, an intelligent dead reckoning personal navigator, and evolutionary strategies for the determination of Earth gravity field parameters. Some of the authors are members of IAG Sub-Commission 4.2 – Working Group 4.2.3, which has the main goal to study and report on the application of AI in Engineering Geodesy.
TL;DR: In this paper, an adaptive Kalman-filter algorithm is applied to selected parts of the grid with predicted major displacements to improve the adaptation process of a realistic model calibration, which is very computationally intensive applied on full slope models with a larger grid size.
Abstract: Abstract Landslides are natural geomorphological phenomenas that can cause hazardous situations to men and infrastructure especially in densely populated areas. For the investigation of such events often numerical slope models are used, that describe the mechanical and geological properties of bedrock. However, the adaptation of the model to the monitored data is commonly done by ‘trial and error’ methods. In order to improve the adaptation process, adaptive Kalman-filtering techniques shall be used in terms of a realistic model calibration. Nevertheless, this method is very computationally intensive applied on full slope models with a larger grid size. Since the deformation process is normally restricted to limited parts of the investigation area (e.g. areas close to the surface), the Kalman-filter algorithm may be applied to selected parts of the grid with predicted major displacements. The first part of the paper is focussed on the monitoring design of the landslide ‘Steinlehnen’ (Tyrol, Austria). For this mass movement, a numerical model is currently under development and shall be calibrated by adaptive Kalman-filtering. In the second part, some investigation results for the adaptive Kalman-filtering approach are presented and discussed regarding a still simulated numerical test slope.
TL;DR: The mathematical model of adjustment problem, detailed proposal of application in baseline processing algorithms, and numerical tests are presented.
Abstract: Abstract GPS augmented with pseudolites (PL), can be used in various engineering surveys. Also pseudolite—only navigation system can be designed and used in any place, even if GPS signal is not available (Kee et al. Development of indoor navigation system using asynchronous pseudolites, 1038–1045, 2000). Especially in engineering surveys, where harsh survey environment is common, pseudolites have a lot of applications. Pseudolites may be used in construction sites, open pit mines, city canyons, GPS and PL baseline processing is similar, although there are few differences that must be taken into account. One of the major issues is linearization problem. The source of the problem is neglecting second terms of Taylor series expansion in GPS baseline processing software. This problem occurs when the pseudolite is relatively close to the receiver, which is the case in PL surveys. In this paper authors presents the algorithm for GPS + PL data processing including, neglected in classical GPS only approach, second terms of Taylor series expansion. The mathematical model of adjustment problem, detailed proposal of application in baseline processing algorithms, and numerical tests are presented.
TL;DR: In this paper, a canonical equation system for geodesics on the surface of an ellipsoid of revolution may be represented by canonical equations and its exact solution is given by a definite integral (quadrature).
Abstract: Abstract Geodesics on the surface of an ellipsoid of revolution may be represented by canonical equations. Applying known theorems, an integral of this equation system can be found. Its exact solution is given by a definite integral (quadrature). Using power series, this integral can be calculated with arbitrary precision. As an example, a fourth order solution will be presented, especially for geodetic applications.
TL;DR: In this paper, the authors present two projects under the theme "Integrated Water Resources Management" in order to improve the water supply situation, both funded by the German Federal Ministry of Education and Research, and realized essentially by institutes of the University of Karlsruhe.
Abstract: Abstract The district of Gunung Kidul in middle Java is one of the poorest regions in Indonesia. The essential reason is the acute water scarcity in this karst region during the months of the dry season. As a consequence of the poor living conditions many people have migrated away and therefore the development of the region is stagnating. During the last few years two projects have been initiated under the theme “Integrated Water Resources Management” in order to improve the water supply situation, both funded by the German Federal Ministry of Education and Research, and realized essentially by institutes of the University of Karlsruhe. Geodetic sub-projects are integrated into both projects. Special surveying activities had been, and have still to be, carried out to realise the geometrical basis for several other sub-projects. The particular contributions are 3D cave measurements for visualisation and planning, staking out of drilling points and construction axes, the definition of a common reference system, the surveying of the water distribution network and its technical facilities, the setting up and the management of a geographical information system (GIS), as well as special measurements such as dam monitoring or controlling of a vertical drilling machine. The paper reviews these projects and describes the geodetic activities.
TL;DR: The relevance and status of 3d displacement monitoring in the New Austrian Tunnelling Method is explained and the developed decision support system and the connected Virtual Reality system used to visualise the system results are presented.
Abstract: Abstract The daily geotechnical interpretation of 3d tunnel wall displacements acquired in underground construction projects is an expert task requiring a high degree of experience and qualification. To assist the responsible engineer on site in this sophisticated work, a decision support system has been developed. In the introduction this paper explains the relevance and status of 3d displacement monitoring in the New Austrian Tunnelling Method. Then it presents the developed decision support system and the connected Virtual Reality system used to visualise the system results. In more details, it describes the two major system components (the knowledge-based library and the decision support application), the input data and how these data are stepwise evaluated by use of a pattern matching method and a trend correlation matrix. Finally, the paper summarizes the development as a successful interdisciplinary cooperation of geotechnical, geodetic and informatics experts.
TL;DR: In this paper, a flight was conducted in which a paraglider's performance was measured for various steady state velocities and turning rates; the data were then analyzed utilizing mathematical optimization after appropriate calibration corrections were applied.
Abstract: Abstract Paragliding is unpowered flight in which pilots rely on their ability to navigate rising currents of air to remain airborne. Paraglider flight performance is an important measure of the capabilities of a particular design of a canopy. Most often, the performance characteristics of a canopy are measured as horizontal velocity vs. vertical velocity for steady state flight in still air. The performance curve created using this approach neglects to take into account the effect which turning has on flight. In contrast, the performance surface created from the research carried out in this paper demonstrates the effect of turning on canopy flight; such a representation of performance is novel to the authors' knowledge. To produce this surface, a flight was conducted in which a paraglider's performance was measured for various steady state velocities and turning rates; the data were then analyzed utilizing mathematical optimization after appropriate calibration corrections were applied.
TL;DR: In this paper, a method for updating the SRTM DEM, using InSAR DEM based on the coherence value selection method, is described. But the method is limited to 3-arc-second (90 m) resolution.
Abstract: Abstract The Shuttle Radar Topography Mission (SRTM) was revolutionary because it generated global digital elevation model (DEM) using space-borne radar imaging technology. The SRTM mapped almost 80 percent of the Earth's surface to a 1-arc-second (~30 m) resolution, but generated a lower resolution 3-arc-second (~90 m) DEM. Currently, the low resolution SRTM DEM is updated and interpolated using other higher resolution DEMs obtained from different sources or techniques, such as InSAR, photogrammetry, and airborne laser scanning. Of the many DEM techniques, the InSAR DEM generation technique is recommended due to the large-coverage and the fact that it is a similar technique to that used for the SRTM DEM. This paper describes a method for updating the SRTM DEM, using InSAR DEM based on the coherence value selection method.