If we are given enough values at specific points, we can use Lagrange interpolation to find underlying polynomial
Spline interpolation is a form of interpolation where the interpolant is a special type of piecewise polynomial called a spline. That is, instead of fitting a single, high-degree polynomial to all of the values at once, spline interpolation fits low-degree polynomials to small subsets of the values, for example, fitting nine cubic polynomials between each of the pairs of ten points.
Signature Smoothing using bezier curve interpolation.
Finding if signature are similar using Frechet distance