The first sign of life is the twitching of an eyelid. Its powerful head moves slowly at first but gains speed steadily as it rises into the air. It looks around, pausing for a powerful yawn. But as it opens its fearsome reptile jaws a surprisingly human voice shouts: `And if you pull this lever you can see the mouth move.’
Jez Harris, the animatronics supervisor of the BBC’s Walking with Dinosaurs, pops his head out from behind the huge tyrannosaurus head. With his partners in Crawly Creatures, he has spent two years producing animatronic dinosaur models for the natural history epic. The first part of this, the BBC’s most expensive documentary ever, went out on Monday. Out of a budget of £6m the animatronics cost around £500,000.
Time, weight and lateral thinking are the three crucial factors in Harris’s work. `Time is the most important factor,’ he says. `We’d finish making the creatures for one episode then start on the next one. And we’d have just six weeks to do it.’
Design drawings were the first casualty in the need to reduce time. `Nature had already produced skeletons so detailed drawings weren’t necessary. We just had to flesh out them out,’ Harris explains.
The documentary makers used a variety of methods to bring dinosaurs to life. Computer animation was used for long-range shots such as a dinosaur running across a field. Crawly Creatures created models for close-ups. Large movements, like the dinosaur’s jaws moving, are controlled by a manual operator using mechanical levers. Electronic control is used for the details which make the models lifelike – skin twitching, eyes moving, nostrils flaring.
The Crawly Creatures workshop, behind Harris’s house in the sleepy Oxfordshire village of Fritwell, looks like an engineering jobbing shop, with an array of lathes, drills and grinders.
Most of the animatronic dinosaurs are made from glass fibre and polyurethane foam, with the larger reptiles built on alloy or drilled aluminium frames. These are mounted on rigs or harnesses which a member of the team wears during filming. Keeping a control on the model’s weight is crucial.
Harris’s partner, Richard Gregory, uses his experience of working with a Formula One team to keep the weight of his designs to a minimum.
`We use mutually supporting structures, or natural beams for longer features. In an F1 car, the gearbox doesn’t just change gear, it supports other parts of the car. Each part structurally supports the next. We use the same techniques here,’ he says.
Weight-reducing methods extend right down to the teeth of some models. Some dinosaurs had mouths over 3m long, so when leverage is taken into account the weight of teeth can be significant. Gregory’s Formula One contacts were a useful source of guidance when picking materials such as alloys for the model frames.
Some creatures had to be filmed underwater in the Bahamas, or on top of mountains in New Zealand. Undersea filming posed other problems – salt water interferes with radio waves used for remote control, so mechanical levers had to be sealed into the model.
Most of the electronics used to animate the models, such as servos, were cheap, off-the-shelf components. Faster-acting servos were needed for the eye movements, but a balance had to be kept between their speed and torque and their weight.
During filming of the series the Crawly Creatures team and computer graphics animators helped palaeontologists discover more about how dinosaurs behaved. For instance, modelling and animating the diplodocus showed that its long neck could not be lifted to eat leaves off the tops of trees, as shown in Jurassic Park. The vertebrae wouldn’t allow it. Instead the creatures would be more likely to move their heads from side to side, `vacuuming up’ low-level foliage and plants.
Gregory believes the creatures’ natural structures compare with today’s best designs. `The T-Rex’s head is like a space frame. Extraneous bone had been whittled down to the minimum leaving more space for muscle. The power to weight ratio generated was huge,’ he says.
Crawly Creatures has already moved onto its next project, modelling a human body and all its organs for a medical programme.
Back in the shed, Harris pulls the polythene cover back over T-Rex. But if Walking with Dinosaurs is as successful as previews have predicted, she could be roaring again soon.
Walking with Dinosaurs can be seen on BBC1, 8.30pm, Monday