Hollywood is on the verge of breaking into an entirely new virtual world. Scientists have developed systems to make digital doubles of actors which are so realistic that audiences will never notice the difference. Computer-generated visual effects have long since been used by film-makers to create space ships and monsters. But the latest technology allows them to create models of real people that can be seamlessly morphed into action scenes featuring human actors. "We're just at the cusp of being able to create the actors, the heroes and the stars of the film, using computer graphics as well," says Dr Paul E Debevec, a graphics researcher at the University of Southern California. 'Compelling and convincing' The process of creating a digital double starts with the actor subject, posing for an extremely high-tech photograph. The Aguru Dome, a futuristic-looking photo booth, has been developed to scan a person's face in extraordinary detail. "It's the world's highest resolution face capture system," says Paul Carroll, an engineer with Aguru Images. "It captures not only the shape of your face but the way light interacts with your face from every angle." The actor's head locked in place, lights flashing from 546 directions and 93 computers operating, the device produces one of the most accurate images of any camera system in the world. The data is then used on a computer to manipulate the image. Once animated, film-makers can create action sequences featuring the actor, which never actually happened. "They are completely compelling and convincing," says Mr Carroll. For now, the technology is not designed to replace human performers entirely. It will be used when film-makers need to re-shoot scenes when the actor is no longer available. The star of the movie may have moved on to another project or changed their physical appearance for a new role.