Constrained design of polynomial surfaces from geodesic curves

In a recent work, Wang et al. [Wang G, Tang K, Tai CH. Parametric representation of a surface pencil with common spatial geodesic. Computer-Aided Design 2004;36(5): 447–59] discuss a constrained design problem appearing in the textile and shoe industry for garment design. Given a model and size, the characteristic curve called girth is usually fixed, and preferably should be a geodesic for manufacturing reasons. The designer must preserve this girth, being allowed to modify other areas according to aesthetic criteria. We present a practical method to construct polynomial surfaces from a polynomial geodesic or a family of geodesics, by prescribing tangent ribbons. Differently from previous procedures, we identify the existing degrees of freedom in terms of control points, and our method yields parametric polynomial surfaces that can be incorporated into commercial CAD programs. The extension to rational geodesics is also outlined.