C1C1 Hermite interpolation with spatial Pythagorean-hodograph cubic biarcs

In this paper the C1C1 Hermite interpolation problem by spatial Pythagorean-hodograph cubic biarcs is presented and a general algorithm to construct such interpolants is described. Each PH cubic segment interpolates C1C1 data at one point and they are then joined together with a C1C1 continuity at some unknown common point sharing some unknown tangent vector. Biarcs are expressed in a closed form with three shape parameters. Two of them are selected based on asymptotic approximation order, while the remaining one can be computed by minimizing the length of the biarc or by minimizing the elastic bending energy. The final interpolating spline curve is globally C1C1 continuous, it can be constructed locally and it exists for arbitrary Hermite data configurations.