STAFF shortages are behind the security industry's embrace of intelligence-based systems, which are replacing traditional guards, fixed cameras and remote alarm services.

Bryan de Caires, chief executive of the Australian Security Industry Association, says event-activated detection technology is increasingly used in public places and commercial properties.

In particular, networked cameras and video analytics software have converged into smart systems that can recognise abnormal events and alert the control centre that a response is needed.

"The industry is moving away from guards patrolling around the clock because you can't have people everywhere. It's a huge cost," de Caires says.

"It's far more efficient to have cameras or access controls linked into the network to manage things like appropriate access to buildings, and send out an alarm when there is a breach.

"We're also seeing surveillance systems based on biometrics such as facial recognition, to pick out a person in a crowd.

"One application will pick out a person listed as a problem gambler in a casino, for instance, or a known card sharp. While that's not illegal, casinos like to know when these people are on the premises."

IBISWorld senior analyst Edward Butler says there has also been a big shift away from obvious cameras and visible closed-circuit television systems towards smaller, less obtrusive devices.

"Surveillance is far and away the biggest growth sector in security," Butler says.

"Cameras used to be placed where they could be seen, essentially to send a message that you are being watched.

"That is still part of the agenda, but hidden surveillance of people is much more common now because it's cheaper and easier to do. These measures are aimed less at deterrence than at being able to catch and prosecute offenders."

Rustom Kanga, chief executive of iOmniscient, a local developer of patented intelligent video analytics software, says its products go far beyond previous video motion detection systems.

"VMD works by taking images one at a time and comparing them," he says. "That works very well if you want to catch someone jumping over a fence, but you can't use motion detection in a busy airport or railway station, where there may be 1000 people moving around."

Instead, iOmniscient has developed a non-motion-detection technology that "can see through the crowd" to identify abandoned objects such as bags.

"The biggest problem is not detecting things, rather it's coping with all the false alarms," Kanga says.

"You need to know that a bag has been left unattended in a busy scene after 10 or 20 minutes, but you don't want to know every time a bag is left unattended for a couple of minutes.

"Likewise, you want to know immediately if someone has fallen down, so you can send someone to assist."

The Sydney company has sold more than 20,000 IQ-Infinity systems worldwide since 2004, with applications such as slip and fall monitoring, crowd and queue management, theft or vandalism reporting, people and vehicle counting, and detection of anomalous behaviour such as loitering, running or speeding.

Its latest offering, iQ-Hawk, brings together simultaneous detection and identification capabilities on the same camera. The system was designed to interface with third-party facial recognition systems and its own licence plate recognition system.

The association's de Caires says the new systems allow security personnel to intervene when trouble occurs, instead of viewing the footage for investigative purposes later.

"People want real-time monitoring," he says. "The video has to be available immediately, not seven minutes later, as something terrible may be happening. Compression and transmission are issues, as we're now using megapixel cameras that provide great resolution - but they are bandwidth hungry."

As a result, most surveillance systems are now being deployed over the internet, using internet protocol technology.

De Caires says the electronics sector of the local security market is worth about $2.2 billion a year; closed-circuit television systems account for about $250 million to $300 million, "and we have nowhere near the penetration you see in the US and Britain. There are more than 4 million cameras in London alone".

Nevertheless, there are cameras everywhere in all central business districts, and in most sporting venues, shopping centres, office buildings and transport facilities.

BISWorld's Butler predicts rapid advances in technology such as facial recognition as businesses take advantage of the internet to transmit video.

"One of the previous limitations was the use of tapes to record from surveillance cameras," he says.

"With digital, you can easily store thousands of hours of footage."