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Abstract

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.