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Virtual Environments
One of the key-features of the majority of VR systems is the support
of real-time interactive graphics. As a result of this there is a great
deal of common ground between computer animation research and VR research.
Support for real-time animation and interaction
To support interactive animation, the process of object movement and
update must be highly efficient. Work on the REALISM system has resulted in a highly
efficient collision detection process that can
be used for complex environments.
The system also supports many kinds of object in a scene, some of
which may be explicitly controlled by users, giving an environment where
there is no distinction between autonomous entities and actual users.
This, combined with the ability to define a real-time limit for the
frame update operations, means that the REALISM system is easily extended to
support interactive animation.
Object modelling
Realistic object models that exhibit the necessary features for
existance in a virtual environment are a prerequisit for convincing VR
systems. The REALISM system provides
libraries of predefined geometries, materials and behaviours that can be
used to create the required obejcts. Each geometric object has an
associated material that defines not only its visual appearance but its
physical properties.
Object models are easily extendible, and their behaviour can be
defined by the use of rules and constraints.
Performance issues
Whilst support for real-time interaction is one issue, the
ability to supply updated images at a sufficient rate for
convincing VR is another. Obviously, the primary requirement for this
is high-performance hardware, but software that takes advantage of this
is essential. To allow the use of parallel hardware schemes, the REALISM system has been extended in the
ACE system. This has been developed to
increase the speed of the generation of frame-based animation by
dividing the total work for a given frame on an object basis (i.e.
allocating a certain number of simulated objects to each processor).
The system also supports all the features necessary for real-time
interaction, and work is currently underway to increase this support to
give an even more effecient animation system for use in interactive
applications.
Author: I.J.Palmer
Last update: 15/8/95
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