3D
content creation in the PROMETHEUS project
The
PROMETHEUS project is addressing many issues related to the easy
creation of high quality animated 3D actors. This builds upon
earlier work in virtual
production at BBC R&D, which included the development of
tools for tracking the position of the studio camera, and generating
photorealistic virtual backgrounds using live video.
There
are two basic methods that can be used to represent people in
3D:
Live
texture mapping
This
involves the capture of moving video images from one or more TV
cameras, which are 'mapped' onto some form of 3D geometry. This
produces a 3D model which will look 'photorealistic' when viewed
from a position corresponding to that of the camera which captured
the scene. As the viewpoint moves away from this position, the
appearance of the model will depend on the accuracy of the 3D geometry
onto which the texture is mapped. At simplest, the video image
could be mapped onto a plane, positioned at the point in the scene
where the actor is standing. This allows the actor to walk around
virtual objects and to appear in front or behind them. In the PROMETHEUS
project, BBC R&D has developed a method of tracking the position
of an actor within a virtual studio, which provides the basic position
information needed to support this. However, as the viewpoint is
moved away from the camera position, the flatness of the actor
will readily become apparent! The project will explore the use
of simple non-planar models, derived for example from silhouette
information, to allow a wider range of viewing angles. The aim
is to be able to create and visualise these models in real-time,
using high-end graphics computers that support real-time texture-mapping.
Approaches
based on texture-mapping are likely to provide the most realistic-looking
representation of actors. However, these approaches only allow
the 3D actor replicate the precise movements and appearance of
the real actor. In order to create from scratch, or edit, the
movement or appearance, it is necessary to have a true 3D model.
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