Detection of 3D symmetry axis from fragments of a broken pottery bowl

This paper relates a method to detect three-dimensional (3D) symmetry axis from the fragment of a broken pottery bowl, which is symmetric in the original status (that is, before broken). Firstly, the fragment is extracted from the range image by applying a bias processing, and its contour is detected. Next, the corner points of the 3D fragment are extracted from its contour. Then, the contour of the 3D fragment is separated into 3D curve segments at the corner points, and the partial mouth-edge is determined by reasoning its center coordinates. Finally, by shrinking the range image, a series of partial curves which are in parallel with the partial mouth-edge, is obtained. The symmetry axis is thought as a line passing through the center points of these partial curves, in 3D space. We tested this method by using the real-world range data. The experiment results are satisfactory.