Measuring sub-mm structural displacements using QDaedalus: a digital clip-on measuring system developed for total stations

Charalampous, Elina; Psimoulis, Panos; Guillaume, Sébastien; Spiridonakos, Minas D.; Klis, Roman; Bürki, Beat; Rothacher, M.; Chatzi, Eleni; Luchsinger, Rolf H.; Feltrin, Glauco

doi:10.1007/s12518-014-0150-z

Cited by 23 publications

(16 citation statements)

References 34 publications

(47 reference statements)

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“…The scaling factor method using the camera-to-target distance (Khuc and Necati Catbas, 2016;Yoon et al, 2016) or merging optical system with a total station (Charalampous et al, 2015;Ehrhart and Lienhart, 2015) has no requirement about known geometric information. However, these applications are based on the prerequisite that the camera principal axis is perpendicular to the target surface plane and are thus not suggested.…”

Section: Non-proprietary (Open Source) Optical Deformation Monitoringmentioning

confidence: 99%

Vision-Based Bridge Deformation Monitoring

Brownjohn

Hester

2017

Front. Built Environ.

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Optics-based tracking of civil structures is not new, due to historical application in surveying, but automated applications capable of tracking at rates that capture dynamic effects are now a hot research topic in structural health monitoring. Recent innovations show promise of true non-contacting monitoring capability avoiding the need for physically attached sensor arrays. The paper reviews recent experience using the Imetrum Dynamic Monitoring Station (DMS) commercial optics-based tracking system on Humber Bridge and Tamar Bridge, aiming to show both the potential and limitations. In particular, the paper focuses on the challenges to field application of such a system resulting from camera instability, nature of the target (artificial or structural feature), and illumination. The paper ends with evaluation of a non-proprietary system using a consumer-grade camera for cable vibration monitoring to emphasize the potential for lower cost systems where if performance specifications can be relaxed.

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Section: Non-proprietary (Open Source) Optical Deformation Monitoringmentioning

confidence: 99%

Vision-Based Bridge Deformation Monitoring

Brownjohn

Hester

2017

Front. Built Environ.

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“…For the system combining a camera with a total station, a projection coefficient called angular resolution [50,51] is used to perform the transformation which represents the angle value (a in Fig. 7) from the camera optical axis to a projection line with the projection length ( O I P I j j) of one pixel.…”

Section: Scale Factormentioning

confidence: 99%

Review of machine-vision based methodologies for displacement measurement in civil structures

Brownjohn

2017

J Civil Struct Health Monit

230

125

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Vision-based systems are promising tools for displacement measurement in civil structures, possessing advantages over traditional displacement sensors in instrumentation cost, installation efforts and measurement capacity in terms of frequency range and spatial resolution. Approximately one hundred papers to date have appeared on this subject, investigating topics like system development and improvement, the viability on field applications and the potential for structural condition assessment. The main contribution of this paper is to present a literature review of vision-based displacement measurement, from the perspectives of methodologies and applications. Video-processing procedures in this paper are summarised as a three-component framework: camera calibration, target tracking and structural displacement calculation. Methods for each component are presented in principle, with discussions about the relative advantages and limitations. Applications in the two most active fields, bridge deformation and cable vibration measurement, are examined followed by a summary of field challenges observed in monitoring tests. Important gaps requiring further investigation are presented, e.g. robust tracking methods, non-contact sensing and measurement accuracy evaluation in field conditions.

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“…The results of the repeated and comparative VD observations indicate a VDs measurement precision of approximately 0.3". To investigate the accuracy, we used the lightweight total station-based geodetic measurement system, 'QDaedalus', developed at ETH Zurich (Bürki et al 2010;Guillaume et al 2012;Charalampous et al 2015;Tóth and Völgyesi 2018).…”

Section: Introductionmentioning

confidence: 99%