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Video Surveillance Turns the Corner-PART I
April 12, 2010
Better cameras, smarter software and faster networks enhance systems.
Video surveillance has been around since law enforcement agencies started using closed-circuit TV cameras in the early 1960s. Today, the basic principle might be the same, but what goes on behind the camera is a far cry from a security guard watching a monitor. Digital and Internet-based technologies have made it easier and cheaper to set up and maintain surveillance systems. These days, a camera could be watching you on just about any busy street corner.
Many agencies are already using basic systems that let human operators monitor live scenes remotely and store videos for later review. And recent advances in software and hardware promise to further reduce costs and expand coverage while delivering analytical capabilities that can greatly enhance security.
The newest frontier in video surveillance is content analysis software. Instead of having human operators sit in front of monitors 24 hours a day and try to stay alert, software can now send an alert when a specified activity takes place. For example, a person crossing the U.S./Mexico border or jumping over the fence at a port facility could trigger such an alert.
A major component of advanced analytics involves not only recognizing objects but also tracking their movements. When you are working with surveillance, you want to know where something is and you want to know right away. Each video pixel can have a geospatial coordinate associated with it, and an extensive metadata catalog helps analysts track events. Sophisticated algorithms move from one camera to the next to ensure continuous views.
Another new technology is adaptive learning surveillance software; a cognitive video analytics system that examines video for behavior patterns. The software tracks objects frame by frame to detect variations from established patterns. When it sees such a variation, it sends an alert.
Play, record, rewind
Of course, the capabilities of new software depend to a significant degree on the capabilities of the hardware on which it runs. Most video surveillance setups involve an array of analog and digital cameras and the hardware to transmit, store, play and analyze video.
Storage is a subdiscipline all its own. In the world of analog, the key recording and storage technology is the digital video recorder (DVR).
Encoder devices bridge the analog/digital gap, which is important because analog equipment can be too expensive for many organizations to replace all at once. However, even though their images can be converted to digital format, analog cameras lack many of the features of digital cameras.
Digital cameras that use IP don’t need — but are often compatible with — stand-alone DVRs and can generally operate with a run-of-the-mill information technology infrastructure, such as storage-area network, network-attached storage and Ethernet Category 5 cable with RJ-45 connectors. In contrast, analog CCTV uses the National Television System Committee (NTSC) broadcast standard via coaxial cable.
Digital over IP can reduce costs by consolidating most functions in the server or the camera, which makes the system more scalable. The break-even point is about 40 cameras, even though digital units cost 50 percent to 70 percent more than analog ones. However, IP-based systems can also push the specialized requirements of video management and surveillance to IT departments that probably have little familiarity with them.
But digital video has another characteristic that makes it better for surveillance. Analog’s NTSC standard employs interlacing that draws the video in alternating lines, while digital cameras employ progressive scans — the top-to-bottom, linear painting of an image familiar to anyone who has watched a DVD movie. When frames are frozen in analog video, artifacts can distort the image.