Sculptured surface reconstruction from CMM measurement data by a software iterative approach

The reverse engineering approach is being widely applied in designing and m anufacturing of sculptured surfaces. The first step in the reverse engineer ing process is collection of data lying on the surface. When using a coordi nate measuring machine (CMM) with a touch trigger probe for digitizing data points, the probe radius must be compensated according to normal vectors. Previous works were addressed on the iterative measurement procedure to red uce the error caused by the compensation. The major problem of iterative me thods is time consumption in digitization. This paper proposes a new archit ecture based on look-up table that keeps the estimated normal vectors of th e measurement data to refine the data points digitized by CMM. The digitize d data are first fitted into several NURBS curves by interpolation. The ski nning method is then applied to interpolate these curves. Thus a smooth NUR BS surface can be constructed and more accurate normal vectors of the measu rement points can be obtained to compensate for the probe radius. By using this software iterative technique, we need only one digitization procedure. Therefore, much time can be saved and the efficiency of reverse engineerin g can be improved.