Splines in tension represent an approach to constrained interpolation of smooth surfaces. The constraint is embedded in a user-specified tension parameter. The two boundary values of tension correspond to cubic and linear interpolation.
By applying the method of spectral factorization on a helix, I have been able to define a family of two-dimensional minimum-phase filters, which correspond to the spline interpolation problem with different values of tension. These filters contribute to our collection of useful helical filters. They can be used for preconditioning interpolation problems with smooth surfaces and, in general, for preconditioning geophysical estimation problems with smooth models.