February 28 1999                                                             INNOVATION


Police will soon use virtual reality to re-enact serious crimes,
writes Sean Hargrave

Computer recreates 3D scenes of crimes
RE-ENACTMENTS of crimes in virtual reality will allow the police to "fly" around the scene of a crime to search for new clues.

Greater Manchester Police are experimenting with a system being developed at Manchester University that can recreate a three-dimensional crime scene from police photographs and video footage.

The researchers at the university's computer-science department hope to perfect the system within two years. By then officers could feed in stills and moving images and a computer would create the scene in 3D within a couple of hours.

At present a computer operator has to scan in the evidence and manually build a scene. This can take days.

The system has already been used to prove a police hunch that virtual reality could help investigations. Researchers were asked to recreate a garage in Stockport to establish if officers could then fly around the murder scene and not just rely on the usual photographs and video taken at the crime scene.

According to Professor Roger Hubbold, who leads the virtual-reality team, the police were impressed with what they saw. "They came to us just to ask if the virtual-reality work we were doing could have any input in solving crimes," he says. "I think they went away knowing that it certainly could.

"The aspect of it they like the best is the way they aren't limited to photographs or moving pictures on a television. With 3D virtual reality they can put on a pair of specs and take a tour of the scene as it was when they found it.

"There is also the advantage that we can show them the scene as it was. When the police take videos and photographs they use powerful lights, which can alter the way a room looks. We can get far closer to what the eye would see."

In the garage experiment the researchers recreated the light intensity and distribution from every striplight so the room and adjoining office looked exactly as they would have at the time of the murder. The various surfaces were individually programmed to reflect light as they would in real life. The metal on the inspection ramps, for example, was instructed to reflect more light than a wooden desk in a neighbouring office.

"The police couldn't believe how life-like it was," says Hubbold. "When some of the officers arrived at the garage their colleagues had closed the doors to keep out the public, so it was darker inside than it was when the incident occurred. With virtual reality they could see what the garage looked like to the people involved."

Once the virtual rooms were built, the police were able to walk or fly around the scene, getting any view they wanted. This is not just useful for surveying a scene but can also be used to check what view different witnesses had of an incident to establish if they could have seen what they claim.

The garage recreation is an early experiment and so did not include virtual characters - avatars, as they are known. However, the Manchester team claims it would be a simple step to place witnesses in a scene and move them through a room. The criminal and victims could also be recreated so police could play out different scenarios of how the incident happened. The crime could be shown several times through the eyes of all those involved.

Sound could eventually be added to the system. There are many programmes that can add "spatial audio" to virtual reality. This would mean officers could hear what was going on at the time of an incident as well as see it. They could also place themselves in the position of witnesses to establish if they were able to hear what they claimed.

Detective Inspector David Heap was largely responsible for the approach to Manchester University. He is convinced that virtual reality will be a key technology to fighting and preventing crime.

"I think the team at Manchester University has proven that virtual reality will definitely be a great bonus to our investigations in a couple of years' time.

"One of the main advantages is that virtual reality allows us to freeze the scene of an incident. In real life we can only isolate a location for so long and then life has to go back to normal. With virtual reality we can keep revisiting the scene as we discovered it.

"It will also be useful not to be limited to flat photographs and video footage taken with huge glaring lights that only ever show what the photographer thought was important. With virtual reality we'll get the entire scene and we'll be able to choose our own angles.

"When it is fully operational we'll be using the technology to test whether witnesses really saw what they say they did and then programme the computer with different scenarios so we can see if what we suspect happened could have taken place.

"This is also going to be a useful tool for training. It costs a lot of money to set up mock crime scenes to train officers how to proceed. We could give our recruits a head start by showing them real scenes and instructing them how to find and preserve evidence.

"I can also see this being good for re-enacting car crashes. The computer could be programmed to know how roads react under different conditions and then replay a crash to see who is telling the truth about what happened."

When the system is finished in two years' time Heap says the force, which is the first in Britain to investigate virtual reality, will have to prove it is reliable enough to be used in court.

"We'll test it by shooting a room from one angle and then, in the virtual mode, we'll move around and see if it perfectly matches the real room," he says.

"Then a judge should hopefully accept it. Our experts, who now have to explain verbally what they think happened, will be able show a jury what they believe happened. It should be a lot clearer than words alone."

The Manchester University team has made the virtual-reality software available for free download from the Internet at aig.cs.man.ac.uk.

Reproduced from The Sunday Times, February 28 1999.