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Last Updated: Friday, 13 May, 2005, 16:54 GMT 17:54 UK
How to catch a thief with your PC
Dan Simmons
By Dan Simmons
Reporter, BBC Click Online

With webcams becoming cheaper and their software ever more sophisticated, it has never been easier to put your PC in the front line of your own security, as Dan Simmons has been discovering.

Burglar caught on webcam
Duncan Grisby's system managed to catch a serial burglar red-handed
A computer can be a PC in more ways than one, as 19-year-old burglar Ben Park now knows.

Earlier this year, he was caught on camera by the very computer he was stealing.

Suspicious of a noise, he looked straight into the computer's webcam, which then captured him in the act of walking off with the computer.

Cambridgeshire police praised the set-up - by software engineer Duncan Grisby - as "absolutely brilliant".

The pictures landed the intruder in jail and made headlines around the world.

The thief-catcher says any of us could have done the same.

"The technology to do this has been around for a long time," said Mr Grisby. "Most of the time if you buy a webcam it comes with software that does this kind of job.

"It's more hi-tech than a video camera with a tape in it, but the fundamental idea is not very different at all."

Motion sensor

So just how easy is it? Mr Grisby's own website gives some clues as to how he set his system up, and offers some helpful tips.

A quick search on the internet also brings up a wide range of software options, some of which are free.

But round the clock monitoring is not without its problems.

David Petrook, a video surveillance expert, says: "Video surveillance is continuous. It's streaming video and it takes up a lot of space on the hard disc.

"So where you thought you had a lot of space on your 80Gb hard drive you're going to find that filling up extremely quickly."

Motion detector
Motion detection software removes the need for continuous surveillance
One way around that problem is to make use of motion detection software.

The technology is more commonly used today for face tracking during video conferencing, so you do not need to keep adjusting the camera while talking to friends in order to stay in shot.

However, it will track criminals just as well.

When the PC detects movement it can start saving the recording, so you only store the moments when something moved.

One version can send you a warning e-mail too, although you will need to know the simple mail transfer protocol (SMTP) of your e-mail server, something your internet service provider should be able to tell you.

Be aware that some services do not use SMTP, so you may need to set up an account with one that does.

If you are worried that your pets might accidentally set the whole thing off, on some systems you can select the area of the picture which is sensitive to movement.

So for example, you could set it to only detect anything that stands taller than about a metre.

But what happens if your intruder then walks off with the evidence and steals the PC with the images on? The answer is to send your images to a website.

Again you will need to know a bit of technical information to get your computer automatically to start uploading images to a website, and while many systems come with instructions on how to do this, check if they provide a helpline and be prepared to use it, especially if you are not familiar with uploading images to the web.

Smart options

To do this you will need a webcam and a broadband connection. And the more you spend, the smarter the camera.

One $200 (108) webcam rotates to track movement, while another, purpose-built, home security camera, available at twice the price, detects heat sources using infrared.

More and more sophisticated webcams are coming on the market
More models are beginning to offer on-board recording so you do not need to leave your computer on all the time.

And some companies are offering to cut out the computer's role entirely. By attaching the camera to a broadband router, the images are sent straight to the web.

At around $1,500 (810), some cameras can automatically call multiple phone numbers using internet telephony if they detect movement, send an image to your mobile phone, and even let you talk to the intruder - if you can think of something to say!

So what next? Dr Chiao-Fe Shu, an IBM software developer, is working on a system which some governments are interested in, but is designed to work on a home PC.

He says: "Basically, the system we have here can use a fixed camera to locate the head of a person in a room.

"Then, after it locates the head we control the moving camera, zooming in to capture the face.

"This is probably the first system to be able to track people and also zoom in to capture people's faces. This is something that we haven't seen in the market yet."

The smart surveillance system promises to improve facial recognition and help secure more convictions, although it does require at least two cameras and will not be available until next year.

Click Online is broadcast on BBC News 24: Saturday at 2030, Sunday at 0430 and 1630, and on Monday at 0030. A short version is also shown on BBC Two: Saturday at 0645 and BBC One: Sunday at 0730 . Also BBC World.

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