A direct deformation method

A new free form deforming interface named direct deformation method (DDM) is presented. DDM allows designers to touch and deform free formed surfaces directly, at any point of the surfaces, even if they are represented only by control points and knot vectors. Users do not need to know such parameters that represent surfaces. The deforming actions of a user are used to calculate new parameters that define the deformed shape of the object. The shape is then reconstructed using the new parameters, allowing the user to visualize his or her deformation. This technique is easy to apply and useful for various form representations