Integrated tactile-optical coordinate system for the reverse engineering of complex geometry

To meet the requirement of both high speed and high accuracy 3D measurement for reverse engineering of artefacts, an integrated contact-optical coordinate measuring system is proposed in this paper. It combines the accuracy of contact measurement using a co-ordinate measuring machine (CMM) and the efficiency of full field of structured light optical scanning methods using a projector and two CCD cameras. A planar target printed with square patterns is adopted to calibrate the projector and cameras while three calibration balls are used to unify two coordinate systems. The measurement process starts from cameras around the volume to capture its entire surface, then the CMM's probe is used to remeasure areas of the object that have not been adequately scanned. Finally the combined data from both systems is unified into the same coordinate system. In this paper the hybrid measurement of a guitar body proves the feasibility of this method.