To produce a spline curve with shape control, a C 1 interpolatory rational cubic function, was described and analysed in [1] for use in computer graphics. Two shape parameters were introduced in each interval that provide a variety of shape controls like biased, point, and internal tensions. This rational spline scheme, in general, does not preserve the shape of the given data. To achieve the shape preservation characteristics, the user needed to play with the shape parameters on distinct areas of the curves which, of course, is not a convenient job. This paper, in addition to reviewing, also discusses the above mentioned rational function to solve the problem of shape preservation and describes the scheme for C 1 planar curves. To obtain the visually desirable shape, shape parameters can be adjusted. Furthermore, the curve method in [1] is also extended with a technique that designs a parametric surface interpolant to a given rectangular set of points. A simple cardinal product method is presented, which is equivalent to forming a network of interpolatory rational cubic spline curves through the data points. The shape parameters involved in this approach are variable and can be used to achieve local or global shape control, like point and interval tension. This cardinal product technique produces a C 2 surface and the practical (computational) way that attempts to compute the surface method is nearly C 2.