Advanced stereo matching algorithm for three-dimensional reconstruction of fracture surfaces

Abstract

Stereoscopic scanning electron micrographs were used to reconstruct the microscopic topography of fracture surfaces. By applying an image processing system developed for fractographic analysis, Digital Elevation Models (DEMS) of the investigated surface were obtained using a personal computer. An advanced area-based matching algorithm was developed to reconstruct DEMS from two surface projections. The hierarchical algorithm was applied to the searching procedure, which involved step-by-step decreasing of reference window size to achieve both an increase in the search accuracy and a decrease in the occurrence of matching errors. At first, the reconstruction procedure was applied by using the conventional area-based algorithm to a Vickers hardness indent, the geometry of which is specified. The result verified the accuracy of the system. For more complicated objects such as the ductile fracture surface of SUS329J3L duplex stainless steel, the advanced hierarchical method was required to obtain an accurate reconstruction. The DEM reconstructed using the advanced stereo matching algorithm revealed the detailed features on the fracture surface such as the shape of the dimple patterns.