  Implicit functions provide a fundamental basis to model 3D objects, no matter
they are rigid or deformable, in computer graphics and geometric modeling. This
paper introduces a new constructive scheme of implicitly-defined 3D objects
based on products of implicit functions. This scheme is in contrast with
popular approaches like blobbies, meta balls and soft objects, which rely on
the sum of specific implicit functions to fit a 3D object to a set of spheres.
