Mj. Lai, SCATTERED DATA INTERPOLATION AND APPROXIMATION USING BIVARIATE C-1 PIECEWISE CUBIC POLYNOMIALS, Computer aided geometric design, 13(1), 1996, pp. 81-88
We show that if the scattered data over a polygonal domain can be quad
rangulated, then the space of bivariate C-1 piecewise cubic polynomial
functions on a triangulation obtained from the quadrangulation has th
e full approximation order. We point out that our method is more effic
ient than the Clough-Tocher scheme.