Juries in murder trials are frequently required to examine stacks of crime-scene photos. It can be a daunting task; the number of pictures can often run into hundreds. To make things easier, two policemen in Queensland, Australia, have developed a virtual reality system that can be used to walk witnesses and juries through the scene of a crime.

Resembling the technology in the film Blade Runner that allowed Harrison Ford to navigate a flat via a photo, the Queensland Police's Interactive Crime Scene Recording system will be used for the first time in a murder trial pending before Brisbane's Supreme Court.

Based on Apple Computer's virtual reality technology, QuickTime VR, the system was developed by Snr Sgt Adrian Freeman, who takes a series of crime-scene photos, and Sgt Troy O'Malley, who stitches them together into navigable panoramas.

The result is like being inside a photographic cylinder that can be moved from left to right and up and down. You can zoom in on details of the scene and jump from one panorama to another, which gives the sensation of walking through the crime scene.

To make navigation of the panoramas easier, they are incorporated into an interactive document resembling a Cluedo board; on one side is a map of the crime scene, with hotspots linked to the panoramas. The map may also feature hotspots showing where key pieces of evidence were found.

Click on the hotspot and a photo of the evidence appears in a window to the left. If, for example, the evidence is a shell casing and a comparison test firing was performed, clicking on the picture again brings up a photo illustrating the test.

"It places the jury at the scene," says Sgt Freeman. Although virtual reality and other forms of interactive multimedia have been around for a couple of years, until now their potential has not begun to be realised. In general, the technology has been limited to demonstrating products like cars on the Web.

But last month, a pair of Canadian palaeontologists proposed using virtual reality to document new microscopic organisms. Writing in Palaeontologia Electronica, Patrick Lyons and Laurence Head show how researchers can stitch together images from an electron microscope to create a virtual specimen that can be explored from all angles. They claim the system will "revolutionise micropalae-ontological illustration".

"Interactive media at the moment is like the early days of cinema when they took stage plays and filmed them head on," says Joel Canon, owner of Interactive Photography, based in San Jose, California. "Movies have become a very powerful medium. People have to learn how do this with interactive media."

One of the areas in which interactive media may have a significant impact is education. Just as museums are turning to hands-on displays that teach through exploration, educators are deploying the software equivalents, called interactive illustrations, or exploratories.

Unlike static illustrations, exploratories are micro worlds whose parameters can be changed to see what happens. They often model a phenomenon, like astronomical orbits, or a problem, such as how to build a circuit to light a bulb.

"[Exploratories] are based on Piaget's constructivist theories of learning; learning by doing, learning by being engaged," says Professor Andries van Dam, head of the computer graphics group at Brown University in Providence, Rhode Island. "It's the discovery method of learning."

People have a faculty of graphical intuition, Prof van Dam argues, and things are seen more clearly if they are represented graphically. "If a picture is worth a thousand words, a moving picture is worth a thousand static ones and a dynamic picture that you can interact with is worth a thousand movies." Brown's computer graphics group has been building and experimenting with exploratories since the late 1970s. The advent of Java and the Web has provided an impetus to the effort, promising the means to deliver powerful learning tools over the Net.

Interactive media may also influence the design of software and computer interfaces. Many decry the current state of the art; Microsoft is among them. "We believe that in the next generation of business applications we will use multimedia more and more," says Mr Eric Engstrom, Microsoft's general manager of multimedia. "Information will be presented visually in the form of interactive illustrations. The goal is to bring multimedia to business applications and eliminate the learning curve." To that end, Microsoft last month launched Chromeffects, a technology for creating interactive multimedia and delivering it over the Net.

According to a white paper that accompanied the launch, software will gradually begin to resemble other means of mass communication such as films, TV and radio. Among the methods proposed are interactive 3D interfaces.

Some critics have heard it all before. "Several companies have looked into it and found it difficult," says Jakob Neilsen, a principal of the Neilsen Norman Group, a consultancy in Atherton, California that specialises in interactive design.

"Humans are not frogs, look at where our eyes sit. They point forwards. We've evolved to walk on the savannah, not fly through 3D space." Despite this, Nielsen says the advent of new software interfaces is overdue. "The world is about to change, use-ability is about to take off. The computer interface is still an interface for a calculating machine, but it's becoming a communications tool and it needs an appropriate interface."

For more information on the Queensland Police's Interactive Crime Scene Recording system, see www. apple.com.au/qtvrpolice1.html