Reverse engineering system for functional parts with complex shape

This paper deals with four processes for constructing mathematical models based on measurement data. The first process is smoothing measurement data based on the hypothesis that a small area of a curved surface can be approximated to an ellipsoid. The second process is fitting the measurement data into the cross points between 3D lattice and fill points by approximating ellipse surface. The third process is recognizing surfaces and boundary lines composing a physical model by curvature on points located on the 3D lattice and variance of coordinate values of points. The last process is approximately defining NURBS surfaces by the minimum square method to average positional errors. In addition, complex shapes are used as evaluation models. The results of constructing surfaces show usefulness of the system based on the proposed methods.