Like an otherworldly portal in one of those houses built on an old graveyard in the movies, Lynn Hershman's Difference Engine 3 attempts to breach the line between the physical world and something slightly beyond it. The installation - which will be a permanent fixture of the new ZKM museum in Karlsruhe - consists of a networked group of movable computer screens that allows visitors to the museum and to its Web site to interact in both real and virtual space.
The project is based loosely on the concept of Charles Babbage's original 19th-century Difference Engine, a mechanical calculating machine widely considered the first computer. Whereas Babbage's engine was used to calculate numbers, "This calculates visitors to the museum," says Hershman. "It's about the calculations of all the elements of individuality."
The piece consists of three 22-inch by 34-inch screens - referred to as Bi-directional Browsing Units (BBUs) - equipped with sensors that move the unit in response to the viewers movements. Simultaneously, a QuickCam on the BBU captures the visitor's face and places it on an avatar pictured on the screen within a virtual representation of the gallery. The avatar's eyes are covered with a serial number. All these features address "the dynamic of abandoning the body into cyberspace," says Hershman.
Meanwhile, up to seven Web visitors can wander a VRML version of the museum's 41,800 square meters as avatars themselves. The Web user is able to move models of the BBUs in virtual space, which, through telerobotics, causes the actual BBUs to move, shifting the user's view of the outside world through the unit's QuickCam. It is therefore possible for a person standing in the real museum at a BBU to see himself on the screen surrounded by the ghostly avatars of remote visitors, or to watch while the screen is moved by an invisible hand.
This kind of correlation between worlds real and reproduced is nothing new for Hershman, a Prix Ars Electronica winner who, way back in 1979, produced what is probably the first interactive disc for an installation in which viewers controlled the actions of a character onscreen by skipping through a video disc with a remote-control unit. Much of the work for the new piece, in fact, was done at the same time Hershman was completing the feature-length film Conceiving Ada, a work for which she created a system to render and film green-screen virtual sets in real time.
Much of the hardware and software customization for the DE3 project was provided by Construct Internet Design, which matched Hershman's US$100,000 ZKM grant, the amount of the company's R&D budget for the year. For Construct, says R&D head Mark Meadows, the point of the project was "to try to figure out how to build some information layers between the real and virtual worlds."
He sees possible applications for the BBU interface in developing a shared desktop space for businesses, air traffic control systems, and multiple-user entertainment, as well as for further use in virtual extensions of museums. It's a question, he says, of finding locations that need a connection to the Internet and figuring out "how do you want to get the Internet to hook up to this particular location?"
One of the ways DE3 connects the ZKM museum to cyberspace is through a 72-inch LED screen in the museum's lobby that Meadows calls the "fish tank window," where visitors can see assorted views of the virtual museum space. Among those views is one of the "Purgatory" where avatars are stored as stacks of faces after their journeys through the cyber-galleries are complete, reinforcing the exhibit's there-but-not-there sense of space and identity. "Anyone who goes through the museum," explains Hershman, "ends up in the Purgatory and becomes the ghost of a museum visitor."
