Background

With the increased interest in 3D graphics over the past decade there has also been a steady emergence of character modelling software to create and animate 3D human figures. During the same period a number of systems have also been developed for tracking the motions of a "real world" human being. The prevalent obstacle encountered when using more than one of these software packages and systems is in the area of information exchange. The lack of a standardized skeletal system within this community often forces animation houses and motion capture studios to develop their own proprietary solutions to help smooth the transitions between the systems and software they want to use.

This document specifies HAnim, an abstract representation for modelling three dimensional articulated figures, including but not limited to human beings. This document describes a standard way of representing humanoids that, when followed, allows human figures created with modelling tools from one developer to be animated using tools from another developer.

Design objectives

Three fundamental goals to help guide the development of the HAnim Specification were established. These goals are:

Compatibility:

The features of an HAnim human figure may be implementable in any compliant browser.

Flexibility:

No assumptions are made about the types of applications that use an HAnim human figure.

Simplicity:

Architectural design includes only those features that are necessary for humanoid figure representation and animation.

Using these three simple goals, a straightforward specification has been created that allows direct access to the joint hierarchy of the articulated figure as well as the vertices of the geometry that make up the individual body segments in a way that allows animations to be generated in a model independent manner.