Journal ArticleDOI
Soil deformation measurement using particle image velocimetry (PIV) and photogrammetry
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TLDR
A deformation measurement system based on particle image velocimetry (PIV) and close-range photogrammetry has been developed for use in geotechnical testing as mentioned in this paper.Abstract:
A deformation measurement system based on particle image velocimetry (PIV) and close-range photogrammetry has been developed for use in geotechnical testing. In this paper, the theory underlying this system is described, and the performance is validated. Digital photography is used to capture images of planar soil deformation. Using PIV, the movement of a fine mesh of soil patches is measured to a high precision. Since PIV operates on the image texture, intrusive target markers need not be installed in the observed soil. The resulting displacement vectors are converted from image space to object space using a photogrammetric transformation. A series of validation experiments are reported. These demonstrate that the precision, accuracy and resolution of the system are an order of magnitude higher than previous image-based deformation methods, and are comparable to local instrumentation used in element testing. This performance is achieved concurrent with an order of magnitude increase in the number of meas...read more
Citations
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Journal ArticleDOI
Two-dimensional digital image correlation for in-plane displacement and strain measurement: a review
TL;DR: In this article, a review of the 2D digital image correlation (2D DIC) technique for displacement field measurement and strain field estimation is presented, and detailed analyses of the measurement accuracy considering the influences of both experimental conditions and algorithm details are provided.
Journal ArticleDOI
Root elongation, water stress, and mechanical impedance: a review of limiting stresses and beneficial root tip traits
TL;DR: A survey of 19 soils, with textures ranging from loamy sand to silty clay loam, found that mechanical impedance is often a major limitation to root elongation in these soils even under moderately wet conditions, and is important to consider in breeding programmes for drought-resistant crops.
Journal ArticleDOI
Root responses to soil physical conditions; growth dynamics from field to cell
A. Glyn Bengough,M. Fraser Bransby,Joachim Hans,Stephen J. McKenna,Timothy J. Roberts,Tracy A. Valentine +5 more
TL;DR: Optical flow techniques enable tracking of root surfaces with time to yield estimates of two-dimensional velocity fields, and it is demonstrated that these techniques can be applied successfully to time-lapse sequences of confocal microscope images of living roots, in order to determine velocity fields and strain rates of groups of cells.
Journal ArticleDOI
A novel discrete model for granular material incorporating rolling resistance
TL;DR: In this paper, a 2D discrete model for granular materials with rolling resistance is presented, which consists of a geometrically derived kinematical model, physically based mechanical contact models and locally equilibrated equations governing the motion of the rigid particles; only one additional parameter δ needs to be introduced in the model when compared with the standard discrete element method.
Journal ArticleDOI
Improved image-based deformation measurement for geotechnical applications
TL;DR: The updated approach combines a range of advances in image analysis algorithms and techniques best suited to geotechnical applications and achieves an improvement by at least a factor of 10 in measurement precision relative to the most commonly used particle image velocimetry (PIV) approach.
References
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DissertationDOI
An investigation into the behaviour of pressed-in piles
TL;DR: In this paper, a detailed study of the mechanics of pile installation in sand and a sequence of field tests to examine the behavior of pressed-in piles at full scale was conducted.
Journal ArticleDOI
A Stero-Photogrammetric Method for Measuring Displacement Fields
TL;DR: In this article, a new whole field displacement measuring technique is described which is suitable for measuring planar displacements of any textured plane surface using ordinary photographs, taken from a fixed camera position, and a development of normal stereo-photogrammetric contouring procedures.
Journal ArticleDOI
Particle Motion Tracking Utilizing a High-Resolution Digital CCD Camera
Samuel G. Paikowsky,Fan Xi +1 more
TL;DR: In this article, a unique system has been developed capable of investigating the interparticle interaction in a two-dimensional array of ideal particles using high-resolution digital charge coupled device (CCD) camera and semi-automatic image processing and analysis algorithms.
Journal ArticleDOI
Photogrammetric Capabilities of the Kodak DC40, DCS420 and DCS460 Digital Cameras
Anuar Ahmad,Jim H. Chandler +1 more
TL;DR: In this paper, the authors evaluate l'influence of the taille des detecteurs and of the resolution of diverses cameras numeriques on the precision and l'exactitude.