Three-dimensional reconstruction of fracture surface of duplex stainless steel using stereo matching

The algorism of the reconstruction of three-dimensional topography from stereoscopic SEM fractographs has been developed. This is an area-based multi-step stereo matching algorithm in order to achieve high accuracy, that is, the corresponding points in stereo photography were searched using a large window area and search area without occurrence of mismatching for the first step. For the next step, the sizes of window area and search area were set smaller than those of the first step around the first corresponding point and then the second corresponding point is determined. This procedure is repeated up to fourth step. DEMs (Digital Elevation Model) of the fracture surfaces of ferritic-austenitic duplex stainless steels were reconstructed using the developed algorithm. The DEMs showed slanted surfaces, and direct comparison of the cross sectional topography between the reconstructed DEMs and the real surface was performed. The reconstructed DEM revealed exactly the shape of the dimple patterns and detailed features on the fracture surface.