A Simple Approach to Interactive Free-Form Shape Deformations

In this paper, we propose a set of free-form shape deformation techniques. The basic technique can be described as follows. Given a surface represented by a mesh and a control point, for every mesh vertex let us consider the difference between the control point and the vertex. The vertex is shifted by a displacement equal to the difference times a scale factor where the scale factor is given by a function depending nonlinearly on the difference. The function is bump-shaped and depends on a number of parameters. Varying the parameters leads to a rich palette of shape deformations. The proposed techniques include also shape deformations with multiple (real, auxiliary, and virtual) control points and constrained, directional, and anisotropic deformations. We demonstrate how that the proposed set of techniques allows a user to edit a given shape interactively and intuitively. The techniques use no mesh connectivity information and, therefore, can be applied directly to a shape given as a cloud of points