AGOCG logo
Graphics Multimedia VR Visualisation Contents
Training Reports Workshops Briefings Index

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 A Earnshaw uk