Three-dimensional image rendering of steel reinforcing bars using curvilinear models applied to orthogonal line scans taken by an inductive sensor

A multi-sensor array inductive scanner for rapid imaging of reinforced and pre-stressed concrete

“…The numbers in brackets denote the actual bar diameter (10 mm) and depths of the upper (30 mm) and lower (40 mm) layer. As the figures show, the models produce very accurate results, the repeatability having been substantiated by a wide range of bar diameters and depths [12,16]. These measurements may now be used to construct a 2D grid of the bar positions, as shown in Figure 8c.…”

“…The software allows the operator to take a raw, 2D image of a rebar mesh, separate the layers, obtain very accurate depth and diameter information, and finally to reconstruct a virtual 3D image of the bar arrangement within the scan volume, which can be rotated at will. The algorithms are fast, robust and as far as the team is aware, scientifically novel in this application [4,6,[11][12][13]16]. The key to the success of the technique is founded on four particular properties of the curve obtained from a transverse scan across a steel bar: first, the relationship between the curve width at half-height and the peak height is unique to a given bar at a given depth; second, both the curve and the depth profile may be accurately represented using non-linear polynomial models.…”

GPR measurement of the diameter of steel bars in concrete specimens based on the stationary wavelet transform

“…Except for the Haar basis, all real orthonormal wavelet bases with compact support are asymmetric [5] . Symmetry is useful in avoiding dephasing in image processing.…”

“…They also used curvilinear models applied to orthogonal line scans taken by an inductive sensor and the method allows estimates to be made with accuracies of ± 1 bar size and ± 10% cover depth when neither the depth nor the size is available [5] .…”

Differential eddy current testing sensor composed of double gradient winding coils for crack detection

“…In this paper the novel differential ECT sensor composed of double gradient winding coils is researched to detect and evaluate crack position and width simultaneously. In order to image a crack in two dimensions, compared with the point scan imaging sensor the novel ECT sensor can perform line scan which can reduce measurement and advance test efficiency greatly, so it can be called line scan imaging sensor [22]. The ECT sensors usually use the differential structure which can reduce the nonlinear items in output signals [23]- [26].…”