Technology Showcase: PTZ Security Cameras
Feb 1, 2008 12:00 PM, By Jay Ankeney
There is no hiding the innovations in remotely controlled video surveillance cameras.
Most of us grew up under the nightmare tutelage of George Orwell's famous novel 1984, which warned us of the dangers of constant surveillance. Yet the events of recent years have made us reconsider the potential advantages of having someone watching over us — especially in potentially dangerous surroundings.
Today, the presence of surveillance cameras can bring the assurance that someone, somewhere will at least be alerted in case of trouble — if not actually come to our aid. In addition, having an unblinking electronic eye overhead is one of the most powerful deterrents to both theft and intrusion. Truly, being under someone's watchful surveillance has become part of our existence — and as long as that observation does not become part of a massive control organization run by a ubiquitous governmental Big Brother, most of us are resigned to its eternal vigilance.
As a result, the installation of remotely monitored and controlled surveillance cameras, known to the AV industry as pan, tilt, and zoom (PTZ) cameras, has become a rapidly burgeoning business. Often referred to as a network camera or an IP camera because of its connectivity, a remotely controlled PTZ camera system combines an analog — or more commonly digital — camera mounted on a motorized control head with communication capabilities to a remote-monitoring site, and it features either automated or humanly directed control and observation capabilities.
The market research firm Frost & Sullivan estimates the network video surveillance camera market in North America alone will grow from more than $200 million in 2008 to more than $800 million by 2012.
Recent trends have given these cameras, usually mounted in protective domes, the ability to pan up to 360 degrees and move at varying speeds. Equipped with full-color imaging sensors for daytime operation, they can see in the dark with the help of removable infrared filters, and they incorporate sophisticated motion-sensing technologies that can detect when an object enters or is removed from the scene.
Control technologies are available from many of the PTZ camera manufacturers themselves. There are also third-party software packages from other vendors that often provide additional functions and access to dozens of cameras by multiple operators. The front-end user interface for a PTZ camera can range from a dedicated control console to the up/down/left/right arrows on a digital video recorder or a joystick on a keyboard connected to the Internet. Many have built-in motion and/or object-recognition capabilities to help detect activity in their coverage. Most systems can be programmed to scan a repeatable tour of specific preset areas, while also intentionally not observing other zones the operators have determined to be off limits.
The reach of PTZ cameras has also been extended with improved optical-zoom lenses reaching out up to 36X — and even that can be vastly extended to the point of pixelation with the addition of digital zoom technology. Several of these zoom lenses provide extra-wide-angle views in addition to increased telephoto range, and new-image digital signal processing (DSP) stabilization algorithms help make those pictures discernable even at maximum zoom. An increasingly common feature is some form of 180-degree autoflip that inverts the image if an object's course moves underneath the camera and passes by. That way, the operator doesn't have to stand on his or her head to identify the image as it rotates through the scene.
Some models also have the capability of picking up sounds from their local environment, and they can be loaded with prerecorded verbal warnings that can be broadcast in case an outsider invades their field of observation. That's why visitors to London often report hearing a disembodied voice from above if they have parked in a forbidden zone.
The domes that house these cameras are often heated and cooled internally to protect the cameras' electronics, and their ability to withstand the elements is specified by Ingress Protection (another use of “IP”) ratings that have been developed by the European Committee for Electrotechnical Standardization. An IP rating normally has two or three numbers: The first indicates protection from solid materials (dust and dirt); the second relates to protection from liquids (rain or direct sprays); and the third reflects protection against mechanical impacts (dropping the dome or whacking it with a baseball bat). Because the last is pretty hard to determine — and not always flattering to the manufacturer — it is often omitted. The higher the number, the better, so a dome with a rating of IP66 should ensure protection against the threat of blowing dust and high-pressure water jets from any direction.
This would all be useless, of course, if these surveillance cameras couldn't send out some kind of call to action. Although this technology started in the analog era — with cameras distributing their surveillance vision over coaxial, unshielded twisted-pair (UTP), or fiber-optic cable — today, most of the latest models of these surveillance cameras are digital, and they have built-in web browsers. That way, they can send their messages over the Internet using a TCP/IP network to anywhere in the world, letting IP operators globally oversee their operational status and observe any activities that seem out of place. These days, a remotely controlled digital PTZ camera can phone home with warning alarms, text messages, Wi-Fi calls for help over IEEE 802.11g to a PDA, or specifically targeted email alerts over the Internet.
Internet Protocol (returning to the more common use of “IP”) has enabled these remotely controlled PTZ cameras to be monitored and directed from anywhere with web access. The downside of IP connectivity can be a delay in sending the video packets across a network unless the system has a very large bandwidth capability. Recent improvements in compression technology, such the H.264 version of MPEG-4, have greatly increased the immediacy of these cameras' communication, and they are being adopted more frequently.
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