The days of stunt men or women leaping from burning buildings, tumbling down stairs or clinging to fast-moving trains may soon be over. Virtual stunt artists are waiting in the wings, and are not afraid of anything. Better still for film producers, they do not need insurance.
A postgraduate researcher at the University of California, Los Angeles – just down the road from Hollywood – has developed "virtual actors" that react to the physics of the real world, rather than having to be laboriously "instructed" by a human illustrator. The virtual actors respond correctly to gravity, friction and impact with other objects.
That means that realistic, but completely virtual, stunt artists could soon be appearing on film screens.
Petros Faloutsos, the system's developer, told New Scientist magazine that the software produced a skeleton that could be digitally "dressed" as any film star using digital technology, and so appeared to do things real film stars were not allowed to.
With the notable exception of the kung fu star Jackie Chan, modern stars are never allowed to perform their own stunts, even if they say they do, because their insurers forbid it. In Mission Impossible: 2, Tom Cruise appeared to be hanging on a cliff face, but in fact wore two harnesses that were digitally erased after filming.
Silent screen stars, notably Buster Keaton, often did their own stunts, although Harold Lloyd's famous clock-hanging scenes in the 1923 film Safety Last used tricks of perspective. He was in fact a few feet above a terrace.
Modern stunt artists may be the most skilled people on film sets. But computer technology has already started eating into their territory: explosions can now be digitally added to films in the cutting room. That means stars can appear in a scene which, if it were done in real life, would be too dangerous for them.
"Inevitably we will be replaced some day," conceded Andreas Petrides, a stuntman based at Pinewood Studios, near London, who co-ordinated the fighting in Star Wars 1: The Phantom Menace. The film had the largest amount of digital post-production of any non-animated movie.
"It comes down to money. If computers can do what I do, but for cheaper, then the studios will go with them."
Virtual stuntmen, he noted, would be able to do the things that their human forebears could not, such as being filmed falling from a building, all the way to the floor.
With a human, that requires two shots – one of the stuntman falling on to an huge inflated cushion (which is kept out of the shot) and a second showing the aftermath.
However, Jackie Chan said recently in an online forum: "I believe that today's audiences are very clever. They can tell the difference between a real stunt and a special effect." Chan added: "I could do 10 movies a year [and] jump between a building in every film. But it only takes one miss for me to die."