There a two standards groups involved:

• VRML h-anim
• SNHC (MPEG4)

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VRML h-anim

h-hanm defines the following PROTOs:

Instances of these PROTOs are used to build a humanoid as follows:

SNHC (MPEG4)

SNHC stands for Synthetic/Natural Hybrid Coding and deals with the representation and coding of synthetically and naturally generated audio-visual information.

VTC stands for Visual Texture Coding. It is a still texture-coding algorithm that is particularly well suited for 3D coding/transmission, because of its scalability capabilities. JPEG2000 is a similar texture compression method incorporating wavelet technology, but standardized for another application domain, i.e. for very high quality 2D image compression applications.

The Animation Framework extension (AFX - pronounced 'effects') provides enhanced visual experiences in synthetic MPEG-4 environments. The framework defines a collection of interoperable tool categories that collaborate to produce a reusable architecture for interactive animated contents. In the context of AFX, a tool represents functionality such as a BIFS node, a synthetic stream, or an audio-visual stream. AFX utilises and enhances existing MPEG-4 tools without sacrificing backward compatibility by offering: · Higher-level descriptions of animations (e.g. inverse kinematics) · Enhanced rendering · Compact representations (e.g. subdivision surfaces) · Low bitrate animations · Scalability based on terminal capabilities (e.g. parametric surfaces tessellation) · Interactivity at user level, scene level, and client-server session level · Compression of representations for static and dynamic tools. Compression of animated paths and animated models is required for improving the transmission and storage efficiency of representations for dynamic and static tools.

Nodes - Body -3D Mesh

Nodes - Face - 2D Mesh

from Marius Preda, MPEG-4 Face and Body Animation (FBA) standardize two type of streams in order to animate an avatar. The first one is the so-called definition stream (Face Definition Parameters - FDP or Body Definition Parameters BDP ) which is based on the h-anim 1.0 specifications. More precisely the BDP Node from MPEG-4 contains the Humanoid Node from h-anim. The second stream is specific to MPEG-4 and deals with motion parameters. That is, in order to animate a face model you need a FAP (Face Animation Parameter) file and to animate a body model you need a BAP (Body Animation parameters) file. Moreover MPEG-4 standardize the compressed form of such an animation stream (two technics are currently adopted: DCT-based and prediction-based). Using the compressed form of the animation parameters one can perform face animation with a bitrate of 2kbps or body animation with a bitrate between 10 to 30kbps. Actually, MPEG-4 addresses new animation functionality in the framework of AFX group (the next version 5 of the MPEG-4) by including also a generic seamless virtual model definition and bone-based animation. More information related to the MPEG-4 SNHC standardization effort is available on the SNHC home page : http://www.sait.samsung.co.kr/snhc or on SNHC email reflector : mpeg-snhc@gti.ssr.upm.es Hope this help, Regards, Marius Preda MPEG-4 FBA Co-chair.