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Video Cameras
(Chapter 2   Video Surveillance, Continued)

Fixed versus pan-tilt-zoom cameras

Two types of camera configurations are available on the market: the fixed camera and the pan-tilt-zoom camera. Fixed cameras are mounted in a stationary position (although what the camera is mounted on may actually move, such as on a police vehicle). These cameras will view the same scene until physically relocated. The scene is typically recorded and, less often, the scene is also viewed simultaneously on a monitor by security personnel.

Pan-tilt-zoom cameras can operate in either of two modes. The mode for which these cameras are most useful allows the scene that is viewed to be controlled by an operator sitting at a video monitor. This operator can control the direction and angle of the camera as necessary. These cameras typically have a zoom option that will allow the operator to focus on parts of a scene, such as zooming in on a suspected perpetrator. The second mode for pan-tilt-zoom cameras is an automatic mode, in which the camera automatically scans back and forth over a certain portion of its range. Normally a pan-tilt-zoom camera should be protected and shielded from view by an opaque enclosure (domes are quite common) so that it is difficult for a would-be perpetrator to tell where the camera is actually aimed.

Exhibit 2.06Most applications in schools are better served by fixed cameras. One consideration is that the pan-tilt-zoom camera can cost around three to five times as much as an equal quality fixed camera. More important, though, is the fact that pan-tilt-zoom cameras, when run by an operator, consume the time of a security staff member. When run in automatic mode, the chance of the pan-tilt-zoom camera looking (and recording) in the direction where an incident is occurring is much less likely than the chance that it will be looking in the wrong direction (exhibit 2.6). Pan-tilt-zoom cameras also introduce a mechanical component to the system that will require more regular maintenance (e.g., oiling gears, replacing motors, and so forth) and that will be one of the more likely fail points.

Pan-tilt-zoom cameras may be employed during a fixed portion of the day, such as the lunch period, if an operator is available to watch and track suspects with this camera. Gateway High School in Denver, Colorado, has a dozen fixed cameras located throughout the campus but also successfully uses one pan-tilt-zoom camera overseeing the parking lot that allows an operator to watch suspected perpetrators before and after classes. Gateway's goal is to record a suspected individual while he or she is involved in a regularly occurring incident of which the school is already quite aware.

With these considerations, it would usually be more cost-effective and more reliable to capture incidents using multiple fixed cameras looking in different areas from a single point than to use a single pan-tilt-zoom camera. (This does not take into account installation costs.)

 



Research Report:   The Appropriate and Effective Use of Security Technologies in U.S. Schools