Abstract
This paper deals with a method of generation of parametric cubic spline surface representing free-form surface defined by contour curves. The method comprises four steps. The first step makes spline curves approximating contour curves. The second step sets the target value of partial second derivatives of the spline surface to be generated at all knot or mesh points, interpolating the shape of contour curves. At the third step, the characteristic vectors at the knot points are so decided that the difference of the actual partial second derivatives and their targets is minimized. The last step computes the final shape of the surface, utilizing twist vectors at the corner points whose obtaining method is also described. Examples show the accuracy of generation.
