Bivariate cubic spline space and bivariate cubic NURBS surfaces

In this paper, we study the bivariate cubic spline space S/sub 3//sup 2,1/ (/spl Delta//sub mn//sup (2)/) and construct a kind of bivariate cubic NURBS surfaces by using the bivariate B-spline bases in S/sub 3//sup 2,1/ (/spl Delta//sub mn//sup (2)/). Compared with the bicubic NURBS surfaces, this kind of bivariate NURBS surfaces are non-tensor product surfaces on the type-2 triangulation with many good properties.