Patent ID: 7400323

Claim:
A computer-implemented process for creating a parametric surface having a required geometrical continuity Gi, from a set of parametric elementary surfaces, comprising the steps of: providing a set of parametric elementary surfaces, each elementary surface having edges, with vertices joining adjacent edges, each elementary surface having an internal continuity Cj at least equal to the required continuity Gi, the geometrical continuity between at least two elementary surfaces, across an edge, being less than the required continuity Gi; and for each singular vertex, said each singular vertex joining at least one edge across which the continuity between adjacent elementary surfaces is less than the required continuity Gi: if said singular vertex is a closed vertex: defining a system of equations linking parameters of the parametric elementary surfaces across all edges joined to said singular vertex and enforcing the required geometrical continuity across said all joined edges; if said singular vertex is an open vertex or a closed vertex joined by a sharp edge: computing at least one sector determined as a space spanned by edges joined to said singular vertex excluding sharp edges, and, for said at least one sector, defining a system of equations linking parameters of the parametric elementary surfaces across edges within said at least one sector and joined to said singular vertex, said system of equations enforcing the required geometrical continuity across said joined edges within said at least one sector; and solving said system of equations to obtain the parameters, wherein said steps are implemented using a computer.