Direct object shape detection based on skeleton extraction of a light line

A simple, fast and accurate light line technique for direct detection of 3- D shape is presented. This technique is proved by simulation and experiment ally verified. To obtain the surface shape, the object is moved along an ax is with an electromechanical device and scanned by a projected light line. Based on the measurement of displacement that suffers the projected line on the surface, object high data is obtained. Light line displacement is acqu ired by determining the precise position of its maximum on the object's sur face and is compared with that projected on a reference plane. The describe d method has the advantages over conventional fringe pattern contouring tha t it is not necessary to design software to obtain the fringe phase and a p hase-unwrapping step does not have to be applied. Another advantage is proc essing time, because the maximum is extracted using an efficient algorithm to fit a concave function with the light line intensity profile. The techni que is quite skilled, robust, and highly accurate, and it can obtain the fo rm of an object with complicated surfaces even with difficult details such as occlusions and discontinuities. Line light displacement can be obtained with resolution of fraction of a pixel, and a surface height accuracy up to 0.001 mm can be obtained. (C) 2000 society of Photo-Optical Instrumentatio n Engineers. [S0091-3286(00)03009-9].