Fitting and manipulating freeform shapes by extendable freeform templates

Finding effective and efficient methods to fit and manipulate an existing freeform shape is one of the state-of-the-art topics in computer-aided design. Although general approaches give satisfied results, the computation time and the complexity often prevent their further developments in more complex cases especially in reusing an existing design. In this paper, for a better control of existing freeform shapes, feature based deformable freeform templates are introduced as the bridge between user actions and the existing freeform shapes. By the advantage of the small number of intrinsic parameters, existing freeform shapes are quickly approximated by the deformable templates. Based on the extendable concept, those deformable templates are further developed to match complex freeform shapes. With the distance and the projection mapping, the original shape and the approximated template are associated. Thus, further shape manipulations can be conducted effectively using the shape intrinsic parameters. Numerical experiments are conducted in order to verify the proposed algorithms. It is also described how the matching technique can be applied in computer graphics and computer-aided design applications.