Second, sometimes too many pixels can actually be overkill. Based on typical identification needs of security departments, a 6mm lens and a 1/3-inch sensor chip produces images good enough to identify a person at the following distances: VGA (10 feet), 1.3MP (20 feet) and 5MP (44 feet). In other words, in a 10-foot room, even VGA resolution would be adequate for identification.
Additionally, some megapixel cameras offer multi-view streaming, meaning that just one megapixel camera can isolate different video streams and, in essence, create several virtual cameras (HDTV can do this as well). This solution has been used in retail outlets to have one camera monitoring several registers.
Also remember that low-light performance can suffer with a higher resolution because less light is available to activate the many pixels on the sensor. So, if you require a camera in a low-light setting, make sure to field test that the higher-resolution camera has the lux level for your scene - do not rely solely on data sheet specs.
Application: A company needs to monitor who is coming in and out of a computer storage room. It is a very low-traffic area, but security needs to be able to clearly identify the person in the scene when the access control system is activated.
Technology: Megapixel. While HDTV in a flipped 9:16 format would work well for this situation, there is no need to deliver 30 fps at all times to monitor this doorway. Also, if real-time and post-forensic identification is important, the office security staff needs all the pixels it can get. Storage concerns can be alleviated if they record on movement or integrate the camera with the access control system to record when the door is opened.
Application: A hospital suspects that certain drugs have been disappearing from its pharmacy. They plan to mount a camera to monitor the pharmacists and nurses behind the counter as well as identify people who request prescriptions.
Technology: HDTV. Since the bottles are small and can be passed quickly between people, a high frame rate will be important. Also, if the camera is installed at the proper angle, not only will this wider view enable security personnel to see behind and in front of the counter, but they can also zoom in forensically on the computer screen during a transaction to ensure the proper drugs were entered into the system.
Application: A busy, outdoor common area is a place where students congregate. There have recently been fights there, and the campus police sometimes find it difficult to identify who provoked the fight in the sea of students.
Technology: HDTV. The 16:9 view will give a great overview of the outdoor common area, since the sky is not an important area to record. With many people moving in and out of view, full frame rate will help campus police identify people moving throughout the crowd. Additionally, if someone in a blue jacket instigates the trouble, the central station can dispatch others to look for a specific-color jacket without hesitation thanks to the format's guaranteed color fidelity.
Application: A company notices that someone has been illegally using its dumpster at night. The company wants to install a camera above the wall directly behind the dumpster, but it does not want to install any artificial lighting.
Technology: Neither. Because of the low-light problems presented in the scene, a VGA or SVGA camera with exceptional low-light performance might be all that the company needs. Additionally, since the installation point is directly behind the dumpster - presumably only five feet from where the perpetrator would be standing - a standard resolution image should provide enough pixels per inch for identification at that distance.
Fredrik Nilsson is general manager of Axis Communications and author of the book Intelligent Network Video. A regular contributor on topics of networked surveillance, his popular "Eye on Video" series can be found at SecurityInfoWatch.com.