Abstract: The shape of a mechanical part is composed of a number of specific feature regions, each with their own precision level. If the shape registration between the scanned data and the CAD model is performed when ignoring the precision difference, an inaccurate alignment result will be produced due to the deviation of low fidelity regions. A new registration method taking into consideration of the region precision is proposed. The procedure is divided into several region-to-region matching steps. The regions with high precision are matched. This matching transformation brings a set of standard orthogonal bases for the transformation space, and at the same time it gives registration constraints on some principal directions. The low precision regions are used to do a new matching. By projecting the new transformation on the previous standard orthogonal bases and setting some terms to zero, the model transformation is restricted and has no movement on the principal directions determined by the high precision regions. Our method produces high matching accuracy on high precision regions and low matching accuracy on low precision regions, which is suitable for practical utility in engineering. The experiments on a simulated cube and a real impeller are presented.

Key words: Impeller, Precision, Registration constraint, Shape registration