Feat of Clay

UNIVERSAL CITY —  Like countless other visitors to the ancient Chinese city of Xian--where an emperor decreed about 200 BC that his tomb be guarded by thousands of life-sized, terra-cotta figures of soldiers and horses buried nearby--Swiss professor Nadia Thalmann wondered what it would be like if the buried army came to life.

But Thalmann had the power to make it happen, virtually.

The ebullient professor from the University of Geneva is one of the pioneers in virtual reality, the computer-assisted field that attempts to create three-dimensional, lifelike characters and environments.

Thalmann, whose best known work is the 1987 “Virtual Marilyn”--a computer animated Marilyn Monroe who appeared in several short films--is presenting a preview of her Xian-inspired work today at Virtual Humans 2, a conference that has brought film, animation, Internet and military experts to the Universal Hilton for a series of lectures and seminars.

Her minute-long video segment shows several of the clay soldiers--each of which, according to historians, was carved to look like a real-life member of the emperor’s army--awakening after thousands of silent years guarding the tomb.

“The emperor sought to make sure they would have life after they were gone by preserving them in terra cotta,” Thalmann said. “We sought to give them life with virtual reality.”

There is no mistaking the virtual soldiers on the video for the real things--the computer simulation is not nearly as polished as what Hollywood can do with virtual dinosaurs or aliens.

Thalmann and the graduate students with whom she works do not have the huge budgets studio filmmakers have at their disposal to achieve that polish. But that’s not the only reason their Xian soldiers, which have been three years in the making so far, seem unworldly.

The look and motions of human beings are far more familiar and complex than those of extinct or mythical beasts. Thus, a realistic simulated human is far more difficult to achieve.

But the Xian soldiers are a significant advance over the stiff stick figures that are the current norm for virtual humans. And some of the soldiers’ attributes, such as the way clothing moves on their bodies as they march, is breathtakingly lifelike.

“She may have been one of the first people to work in the field,” said Mike Bean, publisher of VR News, a periodical that is sponsoring the conference that ends Thursday, “but she still practically defines the cutting edge.

“You know what the cutting edge is when you look at her work.”

Thalmann, 49, whose doctorates are in quantum physics and computer science, directed her first computer animation film in 1982, long before the term “virtual reality” came into use. “Dreamflight,” which tells the story of a little space alien who visits Paris and New York, was primarily meant to be a showcase for how computer graphics could be used in animation.

“To my surprise, it got many artistic awards,” she said with a shrug Tuesday.

“Marilyn” was done by Thalmann and her students at the University of Montreal on a grant from Bell Canada. In 1989, she returned to her native Switzerland to found Miralab, a virtual reality research facility at the University of Geneva.

The lab, which attracts graduate students from all over the world (lab sessions are held in English, the most common first or second language among them) currently specializes in research into creating emotional expressions, clothing movement, realistic hair (a particularly difficult problem for human animation) and mouth movements for virtual humans.

The eventual aim of the work is to create virtual humans that will respond to real humans interacting with them via the Internet or in a game environment.

(Conference officials had originally planned to let participants step into the virtual worlds of the Xian soldiers and other works via the use of special hoods and computers to be supplied by the Electronic Data Systems company. But the company pulled out of the conference a couple of months ago because of a plunge in earnings that caused a company crisis).

Progress in interaction is slow. Thalmann’s lab has developed a virtual tennis match, for example, in which a virtual human can successfully react to some of the shots hit toward it by a real human with a virtual racquet.

But the virtual player’s reaction times are so slow, even a demonstration of a game is impractical.

Thalmann said the slow pace of progress is to be expected.

“It’s like being parents of children,” she said. “You have high hopes that a child will be able to walk all alone, and then one day they do. You wait for them to be able to speak.

“This can’t happen in a day.”