PREFACE
Special issue: deformation monitoring
Andreas Wieser1&Alessandro Capra2Published online: 6 June 2017
# Società Italiana di Fotogrammetria e Topografia (SIFET) 2017
Deformation monitoring is an indispensable contribution of geomatics to society and economy. It provides quantitative and reliable information for studying processes in the natural and man-made environment, for risk assessment and for time-ly adoption of appropriate measures. There is a strong geomatics tradition in geomonitoring of ground subsidence, landslides (in the wide sense of types and processes presented by Cruden and Varnes1996), glaciers, and large man-made structures like dams and tunnels, culminating in an extensive body of methods for deformation analysis based on points and networks, see e.g., Heunecke et al. (2013). However, the re-cent advances in areal measurement technologies, terrestrial laser scanning and ground-based radar interferometry in par-ticular, and the increasing adoption of in situ sensing capabil-ities as offered e.g., by fiber optic sensors or inclinometers, enabled geomatics to contribute also significantly to the inter-disciplinary field of structural health monitoring.
Against this background, the 3rd Joint International Symposium on Deformation Monitoring (JISDM) took place in Vienna, Austria, from March 30 to April 1, 2016. JISDM had been initiated to bring together a broad geodetic commu-nity by combining the FIG symposia on deformation measure-ments, and the IAG symposia on geodesy for geotechnical and structural engineering, and to facilitate interdisciplinary
exchange beyond this community. The program included more than 80 presentations which collectively covered me-thodic advances in modeling and data analysis as well as ad-vances in measurement technology and instruments. Practical experience was reported through case studies ranging from geomonitoring, particularly landslides, glaciers, and subsi-dence, to monitoring of man-made structures including dams, bridges, tunnels, railway lines, and buildings.
The contributing authors were invited to submit revised versions of their papers to the Journal of Applied Geodesy or to Applied Geomatics for publication in a special issue, respectively. Seven papers were submitted to Applied Geomatics. They were subject to the normal peer review pro-cess. The four papers collected in the present issue have been accepted based on the reviews.
Frukacz et al. (2017) analyze four aspects representing lim-itations for the detection of small displacements within a net-work of prisms observed autonomously by robotic total stations in a remote, alpine location. They show significant impact of an extra protective housing of the instruments, of apparent diurnal rotations of the rock on which the pillar of one instrument is mounted, and demonstrate that the remaining systematic patterns within the time series of the measurements can plausibly be contributed to uncompensated refraction. Special attention is paid to establishing the orientation of the total stations using the ensemble of monitored points of which none are known to be stable.
Roberts et al. (2017) present a study of GNSS-based defor-mation monitoring of a large suspension bridge. The original time series of coordinates of selected points on the cables and towers of the bridge showed short-term deformations up to 25 cm in height and 1–3 cm horizontally, mainly as a result of traffic load. After low-pass filtering of the data, the remain-ing signal is strongly correlated with temperature, and the GNSS results allow analyzing the non-linear relation between
* Andreas Wieser
[email protected] Alessandro Capra
1
Institute of Geodesy and Photogrammetry, ETH Zürich, Stefano-Franscini-Platz 5, 8093 Zürich, Switzerland
2 University of Modena and Reggio Emilia, Via Vignolese n. 905,
41100 Modena, Italy Appl Geomat (2017) 9:79–80 DOI 10.1007/s12518-017-0192-0
temperature and displacement of the analyzed points. This corroborates the potential of GNSS to support structural health monitoring of sufficiently large structures.
Alevizakou and Pantazis (2017) give a brief recapitulation of the established classification of deformation models into descriptive and behavioral models, and compare various tech-niques for time-dependent descriptive, i.e., kinematic, model-ing. The empirical comparison is based on the performance for prediction of coordinate time series of selected GNSS per-manent stations.
Erdélyi et al. (2017) present a proposal for deformation monitoring of buildings using TLS. Their approach builds on prior work, nicely summarized, e.g., in Neuner et al. (2016), and is custom tailored to structures which can be scanned from underneath and whose main or critical deforma-tions are vertical and approximately orthogonal to the surface. The sensitivity of the analysis is enhanced by replacing the point cloud above predefined, fixed horizontal positions by planar patches obtained through orthogonal distance regres-sion, and calculating the vertical distance between these patches. Measurements obtained for a suspension bridge and the parabolic roof of an elongated warehouse are used to dem-onstrate the application.
While these papers are of course just snap shots of the breadth of topics relevant for deformation monitoring and a
small subset of papers presented at the conference, they will hopefully still be useful for the readers interested in deforma-tion monitoring.
References
Alevizakou E-G, Pantazis G (2017) A comparative evaluation of various models for prediction of displacements. Appl Geomatics 9. doi:10. 1007/s12518-017-0189-8
Cruden DM, Varnes DJ (1996) Landslide types and processes. Special Report—National Research Council, Transportation Research Board 247:36–75
Erdélyi J, Kopáčik A, Lipták I, Kyrinovič P (2017) Automation of point cloud processing to increase the deformation monitoring accuracy. Appl Geomatics 9. doi:10.1007/s12518-017-0186-y
Frukacz M, Presl R, Wieser A, Favot D (2017) Pushing the sensitivity limits of RTS-based continuous deformation monitoring of an alpine valley. Appl Geomatics 9. doi:10.1007/s12518-017-0182-2
Heunecke O, Kuhlmann H, Welsch W, Eichhorn A, Neuner H (2013) Handbuch Ingenieurgeodäsie: Auswertung geodätischer Überwachungsmessungen, 2nd edn. Wichmann, German
Neuner H, Holst C, Kuhlmann H (2016) Overview of current modelling strategies of point clouds for deformation analysis. AVN 123:328– 339
Roberts GW, Brown CJ, Tang X (2017) Correlated GNSS and tempera-ture measurements at 10-minute intervals on the Severn Suspension Bridge. Appl Geomatics 9. doi:10.1007/s12518-017-0187-x
