Rachael Brady Explores New Realm of Scientific Analysis

by Monte Basgall

On a large screen at Duke's North Building, a projected videotape shows a shadowy figure walking through a hugely magnified sperm tail of a fruit fly.

As the person steps forward or stoops to peer at how particular features link up, the display -- a cluster of points of light that seems to float within a special room known as a CAVE -- spookily adjusts its own position to maintain a proper perspective.

"Think of a holodeck on the Starship Enterprise," Rachael Brady told her audience of Duke biomedical engineers as she narrated a videotape made at the University of Illinois (UI) at Urbana-Champagne. "That's what a CAVE system does."

In the science fiction series Star Trek, a holodeck used futuristic optical technology to create a three-dimensional artificial world where Enterprise crew members could spend their leisure time acting out their favorite fantasies. But the goal of this CAVE (a term trademarked by the University of Illinois) and similar facilities built around the world since 1992 is providing scientists and engineers new ways to analyze the real world.

It was during the 1970s and '80s that computer scientists at the University of North Carolina at Chapel Hill and elsewhere first pioneered the technology, called virtual reality, to immerse real people in artificial environments. By donning helmets fitted with viewing screens and manipulating a joystick, molecular biologists could view computer-rendered molecules that seemingly surrounded them in space. Similarly, architects could "float through" electronically created rooms, and astronomers could "soar" over the surfaces of distant planets that had been remotely imaged by space probes.

But virtual reality helmets proved cumbersome, even nauseating, for some users. "In head-mounted displays you cannot see your physical world," Brady said in a later interview. "You cannot see your hands. You cannot see your feet. You cannot see the person standing next to you.

"In CAVEs you still have all that. You have room between yourself and the display to hold up, say, a measuring tape. You can see your hands. That's why I find CAVEs more compelling as a way to do everyday work."

CAVE is an acronym for CAVE Automatic Virtual Environment. The word cave is in part a reference to the simile of the cave found in Plato's Republic, in which the philosopher explores the ideas of perception, reality and illusion, according to a Web site from the University of Illinois at Chicago Electronic Visualization Laboratory, which first demonstrated the technology in 1992.

The idea, said Brady, was to fill an entire theater-like enclosure with computerized virtual reality images by projecting them onto the walls and floor, sometimes even the ceiling. That way, users can experience virtual reality just by walking into the room and looking around. They also wear special tracking sensors so the computer can pinpoint their locations and accordingly adjust the perspective. The effect is further enhanced by donning 3-D glasses.

Brady had moved to Illinois in 1990 after working as a computer image analyst at the Jet Propulsion Laboratory in Pasadena, Calif., and earning her master's degree in statistics at the University of California at Berkeley.

When CAVE debuted in 1992, she was at the National Center for Supercomputing Applications (NCSA) -- within the University of Illinois at Urbana-Champagne -- designing computer software that could render biological and medical data as objects with volume. In that role, she co-authored and became project technical leader on the CAVE "Crumbs" software, which lets computers not only create artificial reality objects in three-dimensions in a CAVE but also allows users to trace out structures of interest on those images.

"Crumbs" is a reference to the trail of breadcrumbs in the fairy tale Hansel and Gretel. It evolved from a brainstorming session in which Brady and colleagues imagined "what would it be like if we could indeed walk through the human brain and leave behind a trail of where we've been," she said. Users can do this tracing in a CAVE by pointing and clicking a kind of three-dimensional version of a computer mouse. Every click inserts a virtual crumb. As an extra touch, the software also morphs the mouse into what appears to be a sword.

During her CAVE demonstration for the Pratt School's biomedical engineering department, Brady showed how one biologist used "Crumbs" to trace the tail length of a fruit fly sperm captured by a confocal microscope and then magnified to CAVE dimensions. Another biologist used "Crumbs" to similarly trace the magnified digestive track of a virtually rendered protozoan. And a veterinary medical professor used the software as a teaching tool to highlight complicated developmental changes in chicken embryos for her students.

At NCSA in 1997, Brady became technical program manager of the Virtual Environments Group, overseeing UI-Urbana-Champagne's first CAVE (they now have two). In 1999, she was named director of the Integrated Systems Laboratory at the Beckman Institute, a special interdisciplinary center also at UI-Urbana-Champaign.

This fall she came to Duke. She is married to David Brady, Brian F. Addy Endowed Director of the Pratt School's Fitzpatrick Center for Photonics and Communications Systems. While David Brady is a professor in the electrical and computer engineering department, Rachael Brady holds the position of research scientist directly under Pratt School Dean Kristina Johnson.

Topping her personal wish list for Duke: a six-sided CAVE -- four walls, plus floor and ceiling -- each delivering back-projected images onto wall-sized screens. The screens would be black when un-illuminated, giving the room a truly cave-like appearance.

Johnson has designed space for the CAVE in a planned new engineering building. Rachael Brady estimated the CAVE's cost at $1.5 million to $2 million, plus the expense for a full-time engineer and administrator to keep it operational.