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As stated previously, B-splines and NURBS give the designer great flexibility over the shape. We have already observed the influence of the knot values (see Figure 1.4) and the influence of the weights (see Figure 1.7). The designer can also operate smooth shape changes by modifying the coordinates of the control points, as shown in Figure 1.12. This possibility will be of great interest when performing shape optimization. The design variables could be the spatial location of the control points of the spline entities, which, given the high degree of regularity of spline functions, will enable us to get a light and smooth parameterization of the geometry and of its update. This point will be discussed further in Chapter 4.

Modification 2

Figure 1.12. Example of shape modification by altering the spatial location of the control points