Measurement Precision and Spatial Resolution with Kriging Digital Image Correlation

The performance of a new global digital image correlation (DIC) approach known as Kriging DIC is assessed by comparison with the classical subset-based DIC through a standard evaluation procedure. This procedure employs synthetic images with imposed planar sinusoidal displacement fields of various spatial frequencies to quantify both the displacement measurement precision and the spatial resolution of DIC algorithms. The displacement precision and spatial resolution are re-defined in terms of two measures of discrepancy that have not been used before but are considered to give a better comparative assessment than was previously possible. The results are presented in graphical form to finally produce an evaluation of the relative performance of the different DIC approaches. These show that the Kriging DIC approach is robust to the measurement noise and has superior performance to the classical subset-based DIC in terms of both displacement measurement precision and spatial resolution. Furthermore, it is found that the best results are obtained when the discrepancy is measured in the normal direction, as opposed to the Y-direction for the quantification DIC performance.