Critical Design Elements for Video Surveillance Systems

A Video Surveillance System (VSS), more commonly referred to as Closed-Circuit Television (CCTV), has been a vital design element in the construction industry for many years. Its main purpose within the workplace is to protect both the Institution and its employees from crime and loss. Monitoring the workplace is crucial for companies to deter unlawful and prohibited or unauthorized behavior, as well as to hold offenders accountable for their actions.

A typical IP (Internet Protocol) - based VSS consists of strategically placed cameras connected to an IT network switch which is connected to both a PC/monitor for viewing and a server & storage unit to access saved video for playback for a pre-determined amount of time. Apart from the cameras, all of this equipment typically resides in an IT or security room, where it can be accessed by a guard or user station to monitor the video. Some of today’s systems leverage a cloud-based architecture that eliminates the need for this backend equipment, but the cameras are still required and remain the focal component of a VSS that affects the aesthetics and architectural planning for the overall design. An important item to note is that almost all IP cameras are designed to support Power over Ethernet (PoE), so a separate, dedicated electrical receptacle for the camera is not required. The cabling that connects the camera to the network provides power to the device. IP Camera w/PoE

Wireless IP Camera IP Camera

PC Switch Server

Storage

Figure 2: Typical IP video surveillance system design

Planning for Camera Coverage The planning of camera locations is a critical element of VSS design. Similar to the planning for wireless access point locations for technology access, the planning for video surveillance is based solely on user requirements, not on code requirements. In terms of common form factors, there are many different housing types for surveillance cameras today. Typical options are shown below: the other form factors are that they are less conspicuous when mounted flush to either a wall or ceiling, and they have a higher vandal resistance than most other types. They also tend to be less obtrusive, as the camera direction is typically not visible to anyone in the general vicinity.

Many different imager types can be installed within the different housings shown above. Fixed Focal Lens, Varifocal Lens, Single Lens Panoramic (Fish-Eye), and Multi-imager Panoramic cameras represent some of the main options available in the industry. A basic description of these camera types is provided below:

Fig. 3: Common surveillance camera housing form factors

The most common form factor for video surveillance cameras in the industry today is dome. IPVM, one of the world’s leading authorities on video surveillance, recently conducted a study that found dome cameras are by far the most popular form factor in video surveillance, with security integrators preferring them to non-dome form factors nearly 2-1. Some of the advantages of a dome camera over • Fixed Focal Lens – The Field of

View (FoV) of the camera cannot be changed unless the lens is changed. • Varifocal Lens – This camera allows for immediate adjustment of the

FoV simply by adjusting the control of the lens/camera. • Single-Lens Panoramic (Fish-Eye )–

A single camera features a wideangle lens typically housed in a dome form factor that provides 360-degree FoV. • Multi-imager Panoramic – Multiple image sensors are contained in a single housing to cover a wide area.

The camera type selected can directly affect the design of the space. By choosing to deploy only fixed single-lens

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“Critical Design Elements of Video Surveillance Systems” continued from page 2

cameras, you may need to install more cameras than if you were to select only panoramics. Fixed single-lens cameras have a limited FoV but provide more detail, while panoramics cover more area in the FoV, but result in a reduction in details captured.

Images 2-3: Typical Fisheye 360-degree camera view vs. conventional fixed camera view

Another question that comes up frequently while designing a video surveillance system is the height at which a camera should be mounted. Specific to outdoor and entryway installations, there can be a desire to install the camera high up on a building façade, light pole, or other structure to help safeguard against the risk of vandalism or obstruction, as well as for aesthetic reasons. Similar to the camera type selection, there are tradeoffs to this approach. The higher the camera is installed, the less likely it is to get facial recognition details. Industry recommendations for camera mounting height vary widely due to these tradeoffs.

A helpful tool in determining the right type and quantity of cameras to provide for a design is the FoV Calculator. This is free software offered by most major camera manufacturers and independent testing labs that help the user understand what type of coverage and image detail they can expect from a specific camera. To create a preliminary design, a floorplan or satellite image is loaded into the program and a camera type is selected and placed onto the plan. By setting parameters such as desired distance, width, and level of detail, the field of view output will show most likely what the selected camera will mounted just above the door at the main entrance to the school. The goal for this camera placement was to view people entering the building. The images at the right of the scene show the representative details captured at 15’ distance from the camera in both day and night vision. The field of view for the camera was set at 80 degrees. As you can see, the details captured are a much higher image quality, as the desired distance is much

provide. See the below examples: less, even though the FoV is double. It

was determined that facial recognition details were of far greater importance when entering the facility than entering the site.

Images 4-5: Satellite images capture 2MP camera mounted above school entrance

The first satellite scene above depicts a two-megapixel (2MP) camera mounted at the corner façade of the school with the goal being to view the NW corner entrance to the site. The images at the right of the scene show the representative details captured at 100’ distance from the camera in both day and night vision. The field of view for the camera was set at 40 degrees, as it was determined the only area requiring coverage by this camera was the NW entrance.

This second satellite scene above depicts the same two-megapixel (2MP) camera Video Surveillance System planning requires a combination of strong engineering skills and knowledge of design aesthetics. While it is understood that surveillance cameras are necessary within the workplace to protect both the institution and its employees from crime and loss, it should also be understood that this goal should be accomplished with the least intrusion into the overall