Reverse engineering modelling of free-form surfaces from point clouds subject to boundary conditions

In product design, a CAD model often needs to be constructed from a physical part. This process is called reverse engineering and is performed through dimensional digitising and CAD modelling. The dimensional digitising results in a cloud of points, which are input for the CAD modelling of surfaces corresponding to the object's features. Consistent with these features, some of the modelled surfaces need to join with positional, tangential or curvature continuity. This paper reports on the incorporation of these geometric boundary conditions in the CAD modelling of free-form surfaces from a cloud of points with non-uniform rational B-splines (NURBS). The described methods are illustrated with some practical, industrial examples and some alternative solutions are briefly described.