Image Correlation for Shape, Motion and Deformation Measurements

Abstract

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Etching Method to create a Random Speckle Pattern on Semi-Solid Cast A356 Aluminium for DIC in-situ strain measurements

“…The nearest neighbor distance (NND) was calculated by the shortest distance from the center of gravity of each pit to another pits center of gravity. It is necessary to obtain at least 3×3 pixels patterns to allow the use of DIC [3,4,16]; hence, only pits with a minimum area of 2.69 μm 2 were selected (area of 3×3 pixels in 63X magnification).…”

“…The pattern also has to show a high speckle density and good contrast to limit errors. It must also be of suitable size, which means it must not be too big, cover an entire grain (for micro-scale level analysis), nor smaller than 3×3 pixels to allow matching in the full field of view [4].…”

Single Source Three Dimensional Capture of Full Field Plate Vibrations

“…Note that [R] allows any 3D rotation, and can therefore compensate for any misalignment of the image verticals with the mirror plane. The calibration process used is a simplified form of the bundled adjustment procedure as described by Sutton et al [11], solving for just the rotation and translation between camera systems. Firstly, using interactive routines from Matlab's image processing toolbox [8], the user manually selects a number of corresponding pairs of points from the true and reflected image, as shown in Figure 2.…”

“…where n 1 , n 2 and n 3 are components of a vector forming the minimal parametrisation of [R], where the direction of the vector defines the axis of rotation, and the magnitude of its angle in radians [11], and t 1 , t 2 and t 3 are components of the translation vector {t}. Hence to calculatex n (β ), the procedure calculates the 3D position of the point P n implied by the true and reflected points and current parameters, using the method described in Section 3.5, and then evaluates:…”

“…There is a wide body on stereoscopic imaging systems, that make use of multiple images of a single scene to provide detailed 3D measurements [7,11]. One approach to stereoscopic imaging is to use mirrors to generate multiple views, saving the complexity and cost of additional cameras.…”