It’s sometimes intimidating but definitely necessary to learn the intricacies of camera technology. Before specifying surveillance for physical security, focus on the threats and the end-result the customer wants to achieve. For applications which require an expansive field of view, such as stadiums and entertainment venues, transportation, Smart Cities, gaming, retail and industrial properties, there are many options available. Cameras on the market include hemispheric panoramic (fisheye); multisensory, multiview 360, 180-degree units; and even omnidirectional devices.

But how do you assess what you need? Mark Espenschied, director of marketing at Digital Watchdog, Cerritos, Calif., said integrators should plan systems around the end use of the application. “Consider how many cameras are needed to cover the area(s). For wide-area general surveillance, weigh the merits of a pan-tilt-zoom [PTZ] on a preset tour versus all-seeing, multisensor panoramic.” He added that multisensor, user-configurable cameras offer a lower cost and more aesthetic appearance than camera ‘trees.’

 

Sorting out technology

Espenschied said multisensor/multiview is similar to having multiple cameras in one housing, but typically require only one recording license in an enterprise video management system. “The alternative is a camera tree with multiple, full-size cameras which require separate recording licenses. Multisensor cameras are typically available with a fixed 180- or 360-degree view and user-configurable where the sensors can be arranged in limitless configurations on a track assembly. Advantages of multisensor cameras are in reduced installation costs (fewer cameras needed) and increased image resolution (better image quality) versus hemispheric fisheye panoramic.”

Another category for wide-area surveillance is the hemispheric fisheye panoramic camera. These can be a single-sensor camera equipped with a fisheye lens to provide a 180- or 360-degree view. Espenschied said hemispheric fisheye cameras need to undergo a process called dewarping. “The issue with hemispheric cameras is that as much as half of the resolution is lost through this process. A fixed 360-degree multisensor camera will preserve the resolution of the individual sensors. Fisheyes are great when the application is right (small areas, or larger areas if you spend more for an extremely high-resolution camera.) But security contractors need to remember that there’s typically a big resolution boost with a multisensor camera and you don’t need to deal with dewarping. Experienced integrators and architects and engineers should compare the overall cost of a system, not the price of one camera against another.”

With omnidirectional units, another category, camera sensors move around on a track for different adjustable views. The track design on which the sensors rotate can incorporate many positions and there are also options to use multiple lenses. Omnidirectional cameras are more sophisticated in that the camera’s internal processing can be adjusted to look in different directions than fixed view or panoramic multisensors. 

“The category of 180- and 360-degree cameras are the same technology, referred to simply as panoramic cameras or as multisensor panoramic or even multisensor cameras,” explained Jeff Whitney, vice president of marketing at Arecont Vision, Glendale, Calif. “They use different technology layouts - all sensors on one side, or spaced equally around the outside surface. Internally these are very sophisticated computer and lens systems.”

 

Multisensor perks versus PTZ

A properly designed multisensor camera can dramatically reduce the surveillance project’s cost while offering improved situational awareness, said Whitney. “A single multisensor camera, for example, can replace multiple PTZ or fixed-view surveillance cameras by providing nonstop, high-resolution scene coverage. Unlike a PTZ, recording is non-stop, 24/7. When a PTZ is zoomed in, only that specific area is monitored or recorded. The same is true when the PTZ is on a program or under control of an operator—only about a 40-degree cone of coverage is typically achieved with the rest of the scene left unmonitored. With a multisensor camera, when a portion of a scene is zoomed in, the entire rest of the coverage area continues to be viewable and recorded. While a PTZ can miss action happening off screen, the multi-sensor camera does not.” He added that the constant movement of PTZ leads to additional maintenance, repair or adjustment.

Whitney offered these design tips for wide area surveillance:

  • “Determine the viewing angles and coverage. If it is a simple view, a panoramic camera may be the most affordable and easiest to install choice. If it is more complex, a multisensor is more likely the best fit.
  • If surveillance is required in a variety of lighting conditions, ensure that the specification calls for day/night capabilities. Some cameras are suitable only for use in daytime lighting conditions, and do not feature a night capability.
  • Look beyond the camera’s listed resolution. Four sensors is the ideal number to provide proper viewing angles and pixel density for most indoor or outdoor scenes. Some vendors try to reduce the complexity of design in their cameras and cut costs by using three sensors. This limits potential viewing angles and means fewer pixels are focused on a specific area, even when the megapixel rating of a three-sensor camera may be higher. And some adjustable view cameras can’t really adjust all sensors to cover any scene.”