Digital humans. The very words conjure images of the polygon personas created for the next blockbuster by production houses like Industrial Light and Magic or Pixar Animation. But there is more to this technology than big-screen eye candy. Take Santos, for example.

A virtual human, Santos may save corporations big money and help the military save lives.

He's a creation of Virtual Soldier Research at the University of Iowa, and was built using algorithms combined with motion-capture data. He can be as tall or as short as his assignments dictate, and everything about Santos -- from his wire-frame skeleton to his muscle movements -- owes its existence to a scanned and digitized human volunteer.

"Human modeling technology today is so refined, we can use it to test products before they're ever produced," said Karim Abdel-Malek, professor of biomedical engineering and director of the Virtual Soldier Research program at Iowa.

Because just about every manufactured product begins its life in the form of CAD data, a reduced prototype version can be loaded into the system, where it appears onscreen in three dimensions. With a mouse click on a control panel that resembles a PDA, an operator can command Santos to interact with the digital prototype, replicating how a human would engage with it in the real world. A physical prototype becomes unnecessary, saving manufacturing and materials costs.

Santos is so good at what he does that Caterpillar has hired him to make sure its heavy equipment is not only ergonomic but easy to service.

"They (Caterpillar) have an interest in serviceability and mental ability," said Abdel-Malek. "We can ask Santos to change an oil filter on a dump truck or some similar task. As he goes about doing the job, we can query any part of his body functions, such as heart rate, temperature, muscle load and others. At the same time, we can watch him work onscreen and observe any problems he might encounter."

Santos is programmed with extensive modeling data, the result of research on the human body. As he moves in response to commands, he sends back information on his comfort level and joint angles. And, if Santos has difficulty completing a task, project engineers will have the correct information to make modifications before the first stage of production begins.

When the U.S. Army needs new designs of combat-ready body armor and other protective gear, it, too, turns to digital human technology. Santos can model the new duds and advise if they are too restrictive, or if the material doesn't have enough give to be useful in the field.

In a demonstration, Santos appeared on a monitor, dressed in desert camouflage. Darkness enveloped an overturned Humvee, and Santos struggled to escape through a narrow hatch opening. After removing his vest and holster, he easily slid through to safety.

Digital modeling of the human body will continue to be refined. One project known as the Visible Human is providing information gleaned from reducing a cadaver to slices only 0.3 mm wide. Resolutions down to the cellular level -- or eventually the atomic scale -- could mean almost limitless scenarios for virtual humans, including forensics and accident reconstruction.

"These new roles will become part of the evolution (of digital humans), largely due to the availability of better computing systems," said Clay Easterly, a senior researcher at Oak Ridge National Laboratory.

Try to imagine crash-test simulations done digitally, where no dummies need to be banged around and only the virtual prototypes are wrecked.

"I can definitely see that happening in the future," said Easterly.