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Imaging on guard

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Greg Blackman finds that, in order to make security systems effective with video analytics, image quality is of paramount importance

Security systems are becoming more proactive – at least that’s the idea behind the Crime Buster, a surveillance system from Dutch company Pebble Group. The system is based on video surveillance installed to protect building complexes or other defined areas, but also incorporates an audio alarm to warn intruders that they’re being watched – and, hopefully, scare them off.

‘In general, security alarms and cameras are reactive systems,’ comments Pascal Broers, business development manager at Pebble Group. ‘An alarm system is activated, alerting a security guard or the police.’ Security video might also be studied after the event as part of a criminal investigation. The Crime Buster by contrast is designed to act as a remote security guard, preventing or limiting damage to property.

The surveillance system operates on the principle of protecting a ring surrounding a core area, which might be a building’s premises. The military employ this type of security setup for protecting its bases, explains Broers. The Crime Buster uses industrial cameras from Sony, automatically relaying a video stream to a control room when activated. The operator then verifies that the alarm is a burglar or trespasser, and triggers an audio alarm to warn the person they’re under surveillance. ‘Suddenly being addressed by the system during the dead of night is designed to startle a would-be intruder. That’s the idea behind the Crime Buster system,’ states Broers.

The software for the Crime Buster is very specific and has to be reliable, Broers says, to avoid false alarms. What complicates matters is that the environment is far less well defined with outdoor detection than indoor detection; parameters like temperature differences and movement from wind and falling leaves have to be taken into consideration.

The video analytics for the system was developed specifically for the Crime Buster by a German video analytics company. The company’s algorithms are used in a security system protecting the German embassy in Kabul in Afghanistan, for instance, as well as in systems protecting nuclear power plants in Germany.

The Crime Buster can also function during heavy snow. ‘Automatically identifying a person in a scene becomes more difficult when dealing with bad weather conditions like heavy snow because there is a lot of movement in the scene,’ explains Broers. ‘Likewise, in darkness it’s important to be reliable.

‘A high-end security system requires excellent image quality, even at night,’ adds Broers. The Sony FCB-EX985E/P camera used in the system provides excellent image quality and near-infrared sensitivity for operating at night. In addition, the camera doesn’t have a focus shift when working in the infrared – which, Broers says, can be the case with some cameras, meaning the image remains sharp. A wide field of view is also important to allow the camera to track two people moving apart and keep them in the same frame.

Pebble Group has four Crime Busters protecting its facility. In Amsterdam, in the financial centre, the company installed the system to monitor an artistic project, whereby coins are produced by an early money press. ‘It’s our first prototype system and it’s still functioning one and a half years after being installed,’ says Broers.

The Crime Buster can draw on up to six or seven fields of detection, which can be interlinked. Broers explains the capabilities of the system: ‘If there is a fence and behind the fence a sidewalk, the sidewalk isn’t selected as part of the protected area. However, the system is advanced enough to react to someone walking on the sidewalk, but without sending an alarm. When a trespasser crosses the fence, though, an alarm is sent. We can interlink different areas to improve how the ring is monitored.’

The Crime Buster is compliant with German protocols for alarm call centres. ‘Normally with outside protection you run into some usability problems, in terms of when to enable the system,’ Broers continues. ‘You can do that on a time schedule, although if someone is working late they trigger the system. We are able to connect the video analytics to the alarm system, so that the outside perimeter is protected when the alarm is set. The camera surveillance centre will have to work with the system, so usability is very important.’

Minimising false alarms

A surveillance system like the Crime Buster requires excellent image quality for the video analytics to function correctly, which has to be the case both during the day and night. Sony’s FCB cameras contain the company’s latest HD image sensors and advanced features, such as auto iris, zoom and focus functionality, near-infrared sensitivity and the management of NIR wavelengths when imaging at night. The FCB camera’s image signal processor manages and enhances the image signal from the sensor, as well as controlling the lens.

‘As soon as you need to automatically analyse image content it becomes important to have a clear image for the software to work reliably with a high detection success rate,’ comments Stephane Clauss, business development manager at Sony Europe’s Imaging Sensing Solutions division.

Many surveillance networks have a control room with a guard watching a bank of monitors displaying the video feeds from the various cameras. Clauss says that today’s security cameras generally need more functionality than just sending an image. ‘It’s difficult for one guard to effectively monitor a bank of 20 camera feeds in a control room. The industry can provide smart cameras with video content analysis to make systems more effective and aid security personnel in a control room,’ he says. The downside of smart cameras, however, is the potential to produce false alarms, which is why it’s important to have excellent image quality and robust analytics to keep false alarms to a minimum.

With an off-site control room, a potential problem is power outages or the video recorder failing meaning the images are not stored. Digital camera specialist Basler has equipped its IP cameras with an SD card slot for local data storage of up to 32GB. In case of a network failure, the camera acts as a backup solution by recording video streams to the SD card.

‘We have a lot of customers with surveillance cameras installed in building complexes and apartment buildings, but which have the network video recorder located off-site,’ says Björn Weber, product manager at Basler. ‘If the video recorder is disconnected for some reason, then Basler IP cameras have the ability to write data onto an SD card ready for download as soon as the connection is re-established.’

The storage capacity of the SD card depends on a lot of factors, such as the codec used and the frame rate. For example, H.264 has a high compression rate so a lot of video can be stored. Also, data doesn’t need to be stored at 30fps and most customers are satisfied with 1fps, says Weber. Recording time on the SD card can vary from a couple of hours to a few days.

Surveillance at electricity plants

Sony’s FCB cameras are sensitive in the near infrared making them more effective when imaging at night, but for advanced vision capabilities in the dark you need thermal imaging. In Stavanger, Norway, Lyse Energy has installed thermal cameras at its electrical substation, in part for perimeter security, but also for monitoring how efficiently the substation is running and preventative maintenance.

Surveillance at the power station is important to help protect against damage from vandalism, for instance, but breakdown caused by wear can be dangerous as well, not to mention costly, explains Torje Knag, CEO of Norwegian security company, Noralarm, which installed the system.

Flir cameras in action at Norway’s Lyse Energy substation 

‘By constantly monitoring several key parts of the electrical substation we ensure that faults are detected as they develop,’ says Knag. ‘In that case, the energy company can reroute the power through other parts of the infrastructure to prevent immediate breakdown. This buys the repair teams some time to order parts and plan the repairs.’

Knag says that combining security and condition monitoring as part of a thermographic installation will lead to 20 per cent fewer breakdowns, which could result in savings in excess of €8 million each year.

Noralarm uses Flir SR-Series thermal imaging cameras for the perimeter protection system. The company chose thermal imaging, in part, as it produced fewer false alarms than alternative intruder detection methods, such as sensor cables or visual light CCTV cameras. ‘Thermal imaging cameras combine really well with video analytics software compared to regular CCTV cameras,’ says Ronny Hjørnevik, installation manager at Noralarm.

Thermal cameras produce footage based on the infrared radiation emitted by the scene, providing high contrast thermal images in all weather and lighting conditions. The false alarm rate at the Lyse Energy electrical substation is close to zero, according to Noralarm.

The Flir SR-Series cameras contain an uncooled vanadium oxide (VOx) microbolometer detector, which in the case of the Lyse Energy substation produce thermal images at a resolution of 320 x 480 pixels, although Flir also offers models with resolutions of 640 x 480 pixels or 160 x 120 pixels. The analogue video output of the cameras is linked to video encoders to digitise the footage. It is then sent over Ethernet to a local server, which analyses the footage and sends it and alarm data to the central Noralarm control room in Stavanger.

For monitoring the substation for mechanical failures, Flir’s A310 thermal cameras are used. These cameras produce thermal images at a resolution of 320 x 240 pixels, making non-contact temperature measurements with a thermal sensitivity better than 50mK (0.05°C). The system will automatically sound an alarm if particular areas within the thermal image reach temperatures higher than the threshold.

‘The four Flir A310 thermal imaging cameras that are incorporated in the alarm system continually monitor the critical parts of the substation,’ says Mikke Ståhl, Noralarm sales manager. ‘If any part of the monitored equipment rises above the threshold temperature an alarm will go off. The energy company can then reroute the power to prevent breakdowns.'