Advances in Vision-Based Human Body Modeling - 3D Modeling and Animation: Synthesis and Analysis Techniques for the Human Body - page 5

Figure 2. Left: Volumetric model defined by 10 cylinders - 22 DOF. Right:
Volumetric model built with a set of superquadrics - 22 DOF.
cylinders (Figure 2 ( left )), or superquadrics (Figure 2 ( right )) have been largely
used. Delamarre & Faugeras (2001) propose to model a person by means of
truncated cones (arms and legs), spheres (neck, joints and head) and right
parallelepipeds (hands, feet and body). Most of these shapes can be modeled
using a compact and accurate representation called superquadrics. Superquadrics
are a family of parametric shapes that can model a large set of blob-like objects,
such as spheres, cylinders, parallelepipes and shapes in between. Moreover, they
can be deformed with tapering, bending and cavities (Solina & Bajcsy, 1990).
On the other hand, in computer graphics, accurate surface models consisting of
thousands of polygons are generally used. Plänkers & Fua (2001) and Aubel,
Boulic & Thalmann (2000) present a framework that retains an articulated
structure represented by sticks, but replace the simple geometric primitives by
soft objects. The result of this soft surface representation is a realistic model,
where body parts such as chest, abdomen or biceps muscles are well modeled.
By incorporating a mathematical model of human motion in the geometric
representation, the HBM comes alive , so that an application such as human body
tracking may be improved. There are a wide variety of ways to mathematically
model articulated systems from a kinematics and dynamics point of view. Much
of these materials come directly from the field of robotics (Paul, 1981; Craig