Distribution
of 3D content using MPEG-4
Although
the content production tools being developed in PROMETHEUS can
be applied to the production of virtual studio TV programmes
incorporating virtual actors, the real benefit of 3D programme
production lies in keeping all the elements in the form of 3D
models right through to delivery to the viewer. In this way,
the programme can be viewed on a 3D display, and the viewer is
free to navigate round the scene, choose his own viewing angle,
or even view the programme immersively, or from the viewpoint
of one of the characters. Furthermore, availability of the programme
elements as distinct 3D objects will support 'object-based functionality',
such as allowing the viewer to choose which virtual presenter
appears in a programme. Object-based representation will also
allow the programme-maker to re-use elements in other productions.
The
MPEG-4 standard offers all the functionality that is needed to
support 3D content representation and delivery. The PROMETHEUS
project will develop ways of encoding the virtual background
and virtual actors using MPEG-4.
The
virtual environment will be represented using BIFS (Binary
Format for Scenes) - a representation based on VRML.
Actors
represented as 'live' texture maps will be represented using
MPEG-4 arbitrary-shaped
video mapped onto 3D geometry. Face & Body
animation tools to animate virtual actor models, with animated
3D meshes to represent clothing. The high quality avatars that
the project aims to produce may stretch the MPEG-4 face & body
tools to their limits, and it may be necessary to investigate
higher quality methods of avatar representation. For more information
on MPEG-4, see the Tutorial
Issue on the MPEG-4 standard in a recent edition of the Image
Communication Journal.
The
MPEG-4 encoding work in the project will build upon the expertise
developed at Queen
Mary & Westfield College on the application of parallel
computing to MPEG-4 encoding. This is one particular aspect
of the project that is being closely followed by Snell & Wilcox,
who are examining which parts of the PROMETHEUS programme chain
would benefit from the production of specialised hardware.
The
project does not intend to model the actual distribution of the
MPEG-4 data; this is being addressed in other projects. For example
the CustomTV project
looked at ways of transporting MPEG-4 over DVB, and this work
is being continued in the SAMBITS project,
in the EU's Framework 5 programme. Two PROMETHEUS partners, BBC
and QMW, are also partners in SAMBITS.
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