Abstract: The invention is a method and computer application, implemented as a computer program, for modifying the shape of free-form Computer Aided Design (CAD) curves and surfaces to eliminate bad gap problems from CAD databases. The change of shape invention is based on an optimization algorithm that modifies a free-form shape to minimize its connectivity gaps while being constrained to minimize any changes in initial shape. The invention can be used to eliminate bad connectivity gaps, tangency gaps, curvature gaps, and gaps based on higher order differential properties. The invention can be used to modify any free-form curve or surface shape that is represented as a linear sum of basis functions. This class of functions includes but is not limited to B-splines, NURBS, and Hermite polynomials.

Abstract: For simultaneous deformations of multiple surfaces, a constraint called a link constraint is created to link two faces that are to be deformed together. The link constraint consists of a relationship between a constraint curve in each face to be deformed. The selected constraint curve may be any curve, including trimmed curves and part of a boundary curve. As the faces are deformed, the link constraint limits the deformation of the faces by acting as a zipper between the two surfaces along the selected constraint curve. For local deformations within a surface, a hierarchy is created within specific areas, known as patches, of an individual face in a model, ensuring that when a patch in the hierarchy is deformed, the deformation affects patches lower in the hierarchy than that patch, but the deformation does not affect patches higher in the hierarchy.