Curve and surface approximation from CMM measurement data

In this paper, a surface fitting method for reverse engineering is presented. This method uses a series of cross-sectional curves to construct the surface model of a part, and all curves with curvature continuity pass exactly through a set of ordered points generated by a coordinate measuring machine (CMM). The idea behind this method is to use the iterative measurement procedure to diminish error caused by compensation for the probe radius. The measurement path generated by the CAD system in each iteration keeps the probing directions normal to the measured surfaces so that the measured error is minimized. After several iterations, if measurement error converges to a pre-determined tolerance value, the generated CAD model becomes finalized. At the current stage, this method can be applied only for smooth surface fitting. Future research will focus on inclusion of discontinuous features in the part surfaces.