AN APPROACH TO SUBPIXEL ACCURACY WIDENING CRACK WIDTH DETERMINATION IN IMAGE SEQUENCES

Abstract. As an extension to existing work on crack detection and subpixel accuracy width determination as a tool for civil engineering material testing, the paper shows algorithmic approach handle widening cracks with relative rotations between related borders. In first time step under zero-load, set of points be tracked through consecutive frames image sequence is defined. Then, subpixel-precise displacement fields are computed data following steps using 8-parameter least-squares matching approach. The triangulated into mesh, changes inner geometry triangles considered mathematical model assuming split each triangle. With this model, deformation vectors derived. Crack candidates determined by thresholding applied vectors’ lengths. After estimation normal, decomposition applied, allowing compute widths shear movements. novel contribution technique, proposed case rotation borders in order reduce systematic errors. includes two separate rigid transformations side.