Abstract: Three measured data supplement methods are presented for reverse engineering of sculpture surface with unknown regions (such as trimmed region or unreachable region).They are ① mending the unknown region of the practical part manually with some solid material before measuring, ②mending the unknown region of the measured data-cloud by designed surface according its surrounding data, and ③mending the gap with triangular Bézier surface or fitting surface automatically. As well as, a NURBS surface reconstruction method is presented based on the initial representation of triangular Bézier surface. Finally, an example of reversing engineering of a motorcycle part is given to verify the efficiency of the presented methods.

Key words: Data supplement Trimmed surface, Reverse engineering, Sculpture surface