Computer Graphics Pioneers visit the University of Bradford
In the week of 4 December,1995 the Electronic Imaging and Media Communications
(EIMC) Unit at the University of Bradford had three distinguished international
visitors, each giving seminars on their work, and having discussions with
staff in the University.
EIMC Unit David Howson Lecture
The first visitor was Prof Brian Wyvill, Director of the Graphics and Animation
Group at the University of Calgary, who gave the first EIMC Unit David Howson
Annual Lecture, in honour of the retiring founder of the Unit, Prof Howson.
In addition to meeting the staff of the Unit, Prof Wyvill also had discussions
with the Deputy Vice-Chancellor, Prof Costall, Pro Vice-Chancellor, Prof
Green, Prof Gardiner, and Ms Amanda Nevill and Mr Tony Sweeney at the National
Museum of Photography, Film and Television.
Prof Wyvill's Lecture was introduced by Prof Howson's successor, Prof Earnshaw,
who welcomed Brian back to the University after graduating with his PhD
20 years ago. His research area then was recursive hierarchical data structures.
After a period at the Royal College of Art, Brian emigrated to Canada and
now lives in the Rocky Mountains in Calgary. (His brother, Geoff Wyvill,
also a PhD graduate - 1976 - from Bradford, emigrated to New Zealand, and
is now at the University of Otago. He also researches in computer animation
and has an animation company). Prof Wyvill gave his lecture on "Computer
Animation - Past, Present and Future"
The Growth of Animation
Prof Wyvill began by describing the elements of animation, including geometry,
implicit and parametric surface definitions, and how objects can be modelled
with outlines, or skeletons, as they are called. His early work examined
recursive structures, where a mathematically-generated pattern repeats to
create a larger shape. Sea horse shapes were shown, and this led on to the
mention of fractals, where the same idea results in more complex objects.
At Calgary, Prof Wyvill's work smoothly made the transition, in understanding,
from 2D to 3D shapes.
'Alien' Animation
Computer animation was defined as a combination of three disciplines: modelling,
motion control, and rendering. Some of his work included sequences for the
film Alien, for example. Up to the mid-1980's, computer graphics was concerned
primarily with rendering. Parametric patches were
the start of suitable modelling methods, but these were rather tedious and
more suitable for representing car bodies and aeroplanes than for 3D cartoon-line
characters.
Scientific Applications
A serious project, which initiated animation for more entertaining applications,
was about oil pumping in Alberta. Apparently, in order to extract crude
oil from the absorbent rock, it was important to know the temperature gradients
which could be set up when pressurised hot water was pumped in to the rock
to displace the oil. Animation was a very suitable tool for this, given
certain parameters about the physical properties of the materials involved.
Trains and Planes
Animation of 3D objects could be started by blending skeletal elements -
primitives - which were in close proximity. For example, if two geometrically
defined spheres were brought ever closer together, then, at a certain distance,
a dog' s bone shape could be created. Taking the idea further, with different
size spheres at varying distances, a dinosaur shape could be made. By 1987,
Prof Wyvill's work allowed a series of such connected volumes or shapes
to follow a trajectory, exhibiting some novel properties. An example of
this, well illustrated with a video clip, was "The Great Train Rubbery",
in which a train shape (Caption 1) followed the bends and undulations of
a roller-coaster-type track, as though the train was made of rubber (hence
the name!). Other animated characters (eg Caption 2) also appear in this
film!
Dynamic Objects
Negative objects can also be created. These allow holes and boundaries to
be defined within objects. Animation is clearly more than meets the eye:
another one shown, called "HiFi Mike", had inbuilt mechanical
dynamics, so that the objects moved in a realistic manner, bouncing on the
floor and off other objects, for example. It also included some speech synthesis
automatically synchronised to lip motion. However, it was admitted that
the computer generated speech was inferior to human speech so a human voice
had been dubbed over the computer's.
Warp Speed
Warping was then discussed, in which 3D space, instead of being linear,
became distorted, so that linear objects created externally were affected
by the distortion. Where this technique was illustrated was when a rubbery
object landed on a firm surface, changed shape due to momentum and
compression, and then bounced back upwards, and regained its original form.
The space just above the surface had been distorting, so that all objects
approaching it were transformed accordingly. Examples shown were "Cartoon
Ball", "Nelson, the Jumping Bear", and "Spike the Slug".
Actors and Objects that behave themselves
Texture mapping onto surfaces, using fractal-type techniques, was illustrated,
with a leafy-covered dinosaur, whose appearance was a topiary bush - a more
formal example of a simulated garden. This represents joint work with Prof
Prusinkiewicz at Calgary. With this technique, and with other solid modelling
techniques (CSG) Prof Wyvill was then able to show progress by comparing
his 1985 train (from the "Great Train Rubbery") with a much more
recent product (Caption 1), which has better detail, texture, and overall
realism. Another interesting effect was demonstrated - that of
the group animation (the work of a PhD student Hongwen Zhang). The "Digifly"
sequence showed simulated insects flying in a group towards a scent source
(a flower) and around objects (each object with its own distorted space
built in and around) - this is known as "behavioural animation",
since group behaviour is modelled and animated to look as it would appear
in real life.
Insects and Dinosaurs - Jurassic Park
Because the space in which they flew was mathematically-defined, each digifly
appeared to be an independent object in flight, and this effect was used
to great advantage in the Steven Spielberg film Jurassic Park, when some
of the cast were running to escape two-legged dinosaurs which resembled
ostriches. This latter special effect was contributed in part by one of
Prof Wyvill's students at Calgary University. The advantage of behavioural
animation is that it enables animators to have a higher level control of
characters in a scene and produce aggregations of objects and characters
which behave in predefined ways.
A Lightning Finish
The talk finished with some lightning strike effects being demonstrated
and explained, using modifications of the techniques already demonstrated.
The talk was very well received, with an excellent representation of staff
and students alike in the audience.
It was also clear that, when animation was seen on the screen, this represented
a considerable amount of work behind the scenes. Particularly, it was a
revelation to see that, in each animation, it might take 20 minutes for
a computer to calculate the image data for one frame, but only 1/24th of
a second to show it in the final product, so that, with a 30 minute animation,
that means 42,300 minutes of computer time, or nearly 30 complete days worth
of calculations!
The second visitor was Prof Jack Bresenham, Professor of Computer Science
at Winthrop University, USA, who gave a seminar on Rapid Prototyping, which
is the ability to create 3D solid objects direct from computer models.
Rapid Prototyping
Prof Bresenham outlined the exciting growth application area for computer
graphics - Rapid Prototyping (RP). In the 1960's subtractive RP emerged
as numerical control (NC) tools became popularly available. Computer aided
design employing graphics workstations helped cut design
time significantly. NC tools then further reduced the time traditionally
required to design and manufacture real prototypes of complex parts. Computer
graphics now can be a key enabling application as additive RP emerges in
the 1990's. To enhance graphics researcher and practitioner awareness of
these new RP technologies, several leading technologies for additive RP
were presented and reviewed. These included stereolithography, selective
photocuring, selective sintering, droplet deposition, fused deposition modeling
and laminated object manufacturing.
Virtual Reality
The third visitor was Dr Larry J Rosenblum, Director of VR Systems and Research
in the Information Technology Division (ITD), Naval Research Laboratory
(NRL), Washington DC, who addressed the current research issues in Virtual
Reality. These included Realism in the Virtual World, Display Resolution,
Input Devices, Interfacing, Acoustics, Sensory Perception, Human Factors,
and Collaborative VR. VR is a highly interdisciplinary field, involving
the disciplines of computer science, computer graphics, imaging, robotics,
acoustics, materials, sensor technology, human-computer interface, and psychology.
Progress will only be made in all these areas by a collaborative and interdisciplinary
approach. Applications areas for VR include simulation and training, design
and manufacturing, medicine and health care, hazardous operations, information
visualization, telecommunications and teletravel.
An Exciting Future!
In conclusion, it is clear that animation, modelling, and VR are all key
areas for the future. The recent production of "Toy Story", the
first completely computer generated feature film, produced by PIXAR for
Walt Disney, marks a watershed in the sophistication of computer animation,
coming as it does 100 years from the first cinema production. The upsurge
of digital effects studios in Hollywood testifies to the growing demand
for digital imaging as we move forward to the 21st century.
R J Green
R.J.Green@bradford.ac.uk
R A Earnshaw
R.A.Earnshaw@bradford.ac.
uk
