Dynamic Concrete Beam Deformation Measuremnet With 3d Range Cameras

Qi, Xiaojuan; Lichti, Derek D.

doi:10.5194/isprsarchives-xxxix-b5-239-2012

Cited by 3 publications

(5 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At higher sampling frequencies the estimates are corrupted by the increased level of range measurement noise. At the 10 Hz sampling frequency the 3 Hz data contain an axial target motion artefact of about 0·6 mm (Qi and Lichti, ). Based on these findings, only the 20 Hz sampling frequency was used to collect data in Experiment II.…”

Section: Results and Analysismentioning

confidence: 99%

“…The biased phase difference:

\overset{false^}{italicφ} = {tan}^{- 1} (\frac{\overset{C}{true} ({italicτ}_{3}) - \overset{C}{true} ({italicτ}_{1})}{\overset{C}{true} ({italicτ}_{0}) - \overset{C}{true} ({italicτ}_{2})})

and biased range:

\overset{false^}{italicρ} = \frac{\overset{false^}{italicφ} c}{4 π f_{m}}

are thus derived. The impact of periodic, axial target motion on the range measurements has been assessed by simulation (Qi and Lichti, , b). They demonstrate that the range bias due to motion can be kept below 0·1 mm if the frame sampling rate and the target motion frequency meet certain conditions that are described later.…”

Section: Range Camera Technologymentioning

confidence: 99%

“…For Experiment I, several different acquisition rates above this limit were tested: 10, 20, 30 and 40 Hz, for which the respective integration times were 4, 8·5, 4·4 and 2·2 ms. Furthermore, previous investigations (Qi and Lichti, , b) revealed that frame rates of at least 10 and 20 Hz were needed to keep the range error due to target motion below 0·1 mm for periodic, axial target motion having frequencies of 1 and 3 Hz, respectively. As will be demonstrated, the results of Experiment I indicated that the best sampling frequency in terms of reconstruction accuracy was 20 Hz.…”

Section: Experiments Descriptionmentioning

confidence: 99%

See 2 more Smart Citations

Structural Dynamic Deflection Measurement With Range Cameras

Lichti

El-Badry

et al. 2014

The Photogrammetric Record

View full text Add to dashboard Cite

Time-of-flight range cameras offer numerous advantages for the measurement of dynamic phenomena, thanks to their ability to directly measure threedimensional coordinates of objects at video rates using only one sensor. This paper reports the results of an investigation into the development of a range camera based system for measuring the deflection of reinforced concrete beams subjected to cyclic fatigue loading. New data segmentation methods and reconstruction algorithms have been developed to reconstruct the time-dependent displacement of the beam with sub-millimetre amplitude and millihertz-level frequency precision and accuracy in all three dimensions along the entire beam length. Moreover, sub-millimetre changes in displacement measurements due to stiffness degradation caused by fatigue are also reported.

show abstract

Section: Results and Analysismentioning

confidence: 99%

“…The biased phase difference:

\overset{false^}{italicφ} = {tan}^{- 1} (\frac{\overset{C}{true} ({italicτ}_{3}) - \overset{C}{true} ({italicτ}_{1})}{\overset{C}{true} ({italicτ}_{0}) - \overset{C}{true} ({italicτ}_{2})})

and biased range:

\overset{false^}{italicρ} = \frac{\overset{false^}{italicφ} c}{4 π f_{m}}

Section: Range Camera Technologymentioning

confidence: 99%

Section: Experiments Descriptionmentioning

confidence: 99%

See 1 more Smart Citation

Structural Dynamic Deflection Measurement With Range Cameras

Lichti

El-Badry

et al. 2014

The Photogrammetric Record

View full text Add to dashboard Cite

show abstract

“…In contrast to laser scanner systems that feature sequential point measurement, ToF data capture within the camera's field of view is nearly simultaneous, except for the integration periods. Although measurement artefacts due to subject motion are possible, these can, in principle, be reduced to insignificance with careful choice of the integration time in relation to subject motion (Qi and Lichti, ; Qi et al., ). The maximum range or the ambiguity interval is governed by the modulation frequency.…”

Section: Experiments Descriptionmentioning

confidence: 99%

The Practical Application Of 3D Vision in the Field: Measuring Reindeer (Rangifer Tarandus) Antler Growth Velocities

Lichti

Steward

Chow

et al. 2016

The Photogrammetric Record

View full text Add to dashboard Cite

Advances in three-dimensional (3D) optical imaging have made possible precise and accurate measurements of many scenes, ranging from engineering to architecture to art. However, measurements of some 3D objects are more difficult to obtain than others, particularly if the edges do not feature regular geometry, the colour is dark and variable, and if the object moves haphazardly. Such objects occur regularly in biology, and the present study illustrates some of the challenges of evaluating such objects. The growing antlers of three live reindeer (Rangifer tarandus) is presented as an example of how 3D imaging, specifically time-of-flight range imaging, can be used to solve to a reasonable extent a problem that is very difficult to approximate using traditional techniques. Mean antler growth velocities of the order of 7 to 9 mm/day were estimated, using the proposed methodology, from data of these three animals collected over a seven-week period. ZusammenfassungFortschritte in der 3D-Kameratechnik erlauben pr€ azise Vermessungen vieler Szenen: von Ingenieurwesen € uber Architektur bis zur Kunst. Dennoch sind die Messung einiger 3D Objekte viel schwieriger zu erhalten als andere, insbesondere wenn die Kanten keine regul€ are Geometrie besitzen, die Farbe dunkel ist und variiert oder wenn das Objekt sich willk€ urlich bewegt. Solche Objekte treten oft in biologischen Anwendungen auf und die vorgestellte Studie pr€ asentiert einige der Herausforderungen, um solche Objekte zu evaluieren. DasThe Photogrammetric Record

show abstract

“…This drawback of having to strategically sample a relatively small number of discrete points for inferring the global deformation pattern can also be seen in other pointbased measurement techniques such as tachymetry and photogrammetry [9,27]. On the contrary, active sensors like 3D range cameras [29], coded-light systems, and terrestrial laser scanning (TLS) systems [18,28] can make dense measurements on surfaces rapidly without markers. Among these aforementioned modalities, TLS equipment generally offers the greatest flexibility for deformation analysis projects.…”

Section: Introductionmentioning

confidence: 99%

Point-based and plane-based deformation monitoring of indoor environments using terrestrial laser scanners

Chow

Ebeling

Teskey

2012

Journal of Applied Geodesy

View full text Add to dashboard Cite

Terrestrial laser scanners are high-accuracy 3D imaging instruments that are capable of measuring deformations with sub-millimetre level accuracy in most closerange applications. Traditionally, deformation monitoring via laser scanning is performed by measuring distinct signalised targets. In this case, the centroid of these targets must be determined with great accuracy for optimum detectability. To achieve this, a least-squares target centroid extraction algorithm suitable for planar checkerboard-type targets is proposed for irregularly organised laser scanner data. These target centroids are then used in a free-station network adjustment for performing deformation analysis with no a priori assumptions about the deformation pattern. To ensure the optimum measurement accuracy, all systematic errors inherent to the instrument at the time of data acquisition needs to be removed. One of the methods for reducing these systematic errors is by performing selfcalibration of terrestrial laser scanners. In this paper, this was performed on-site to model the systematic errors of the scanner. It is demonstrated that the accuracy of the recovered translational movements were improved by an order of magnitude from the millimetre level to the sub-millimetre level using this approach. Despite the success of using laser scanners with signalised targets in deformation analysis, the main benefit of active sensors like terrestrial laser scanning systems is their ability to capture 3D information of the entire scene without installing markers. A new markerless deformation analysis technique that utilises intersection points derived from planar-features is proposed and tested in this paper. The extraction and intersection of planes in each point cloud can be performed semi-automatically or automatically. This new method is based on free-stationing and does not require a priori knowledge about stable control points or movement patterns. It can detect and measure both translational and rotational movements of the planes with minimum human interaction. The effectiveness of the proposed methodology is studied through simulations and real datasets captured with a phase-based Leica HDS6100 scanner.

show abstract

Dynamic Concrete Beam Deformation Measuremnet With 3d Range Cameras

Cited by 3 publications

References 8 publications

Structural Dynamic Deflection Measurement With Range Cameras

Structural Dynamic Deflection Measurement With Range Cameras

The Practical Application Of 3D Vision in the Field: Measuring Reindeer (Rangifer Tarandus) Antler Growth Velocities

Point-based and plane-based deformation monitoring of indoor environments using terrestrial laser scanners

Contact Info

Product

Resources

About