Mathematical Formulation

Figure 1: The flow of information though the system: 2-D observations to a 3-D dynamic model that feeds back to the 2-D observation process.

The human body is a complex dynamic system, whose visual features are time-varying, noisy signals. Accurately tracking the state of such a system requires use of a recursive estimation framework, as illustrated in figure 1. The elements of the framework are the observation model relating noisy low-level features to the higher-level skeletal model and vice versa, and the dynamic skeletal model itself. We will first describe the dynamic skeletal model, and then the observation model and its inverse. Finally we descibe a modification that addresses performance and engineering concerns.