Topological criterion for selection of quintic Pythagorean-hodograph Hermite interpolants

A topological approach to identifying the “good” interpolant among the four distinct solutions to the first-order Hermite interpolation problem for planar quintic Pythagorean-hodograph curves is presented. An existence theorem is proved, together with a complete analysis of uniqueness/non-uniqueness properties. A simple formula for finding the “good” solution, without appealing to curve fairness or energy integrals, is also presented.