Accurate 3-D morphology recovery using binocular parallax and its application to morphological analysis of metal powders

A new three-dimensional morphology recovery technique was developed for the analysis of material microstructures. The principal concepts embodied in the technique are dynamic optimization of the size of matching areas using area-based stereo matching and adjustment of the size of corresponding areas within the search area. Numeric analysis demonstrated that this parallax-based technique makes it possible to maintain phase with geometric distortions; moreover, the resolution achieved with this method in relative height computations is twice that of other methods. Morphology analysis of water-atomized iron powders indicated that the technique recovers three-dimensional morphologies with a level of precision suitable for practical application even with complex forms such as non-spheroidized powders. In addition, use of the fractal dimension as a feature parameter makes it possible to determine whether a powder is spheroidized or not, regardless of differences in observation conditions such as the degree of magnification.