Edge inspection in automatic stitching

The paper describes work relating to the laser line triangulation technique which has been used to inspect the edges of overlapping shoe components prior to the sewing operation. The laser line triangulation technique involves projecting a laser line on to a surface which can be viewed using an area camera. A surface height transition (edge) causes a discontinuity in the observed laser line. Different approaches for extracting the edge positions in the image co‐ordinate system have been investigated based on the Hough transform, the spatial histogram, polynomial regression and the discrete first derivative. These edge detection algorithms are compared in terms of speed and precision performance. Three‐dimensional scans of typical shoe component parts are presented.