Video surveillance technology is a type of closed-circuit television (CCTV) technology dedicated to monitoring some particular area of observation. Video surveillance systems may monitor and/or track people, vehicles, machines, hazardous conditions, etc.
Basic video surveillance systems consist of any number of cameras and monitors, and a communications network to connect them. In addition, there may be video recording devices, video content analysis/object recognition devices (usually based on computers), and/or tracking devices.
Some of the goals for video surveillance are:
- Crime prevention (parking lots, public transportation areas, banks, stores, etc.)
- Safety issues (schools, transportation, public places, etc.)
- Industrial processes (human hazardous areas in chemical or nuclear industry, assembly-lines monitoring). In these applications special cameras may be utilized (thermographic cameras, line-scan cameras).
- Traffic monitoring
- Law enforcement
- Control of working or retail areas
Analog Video Systems
Analog video surveillance systems are generally older and based on analog CCTV technology. Video tape recording is used. The analog signal is transmitted from the camera to the monitoring station through coaxial cable. The resolution and picture quality are low and often unreliable.
Digital Video Systems
Digital video surveillance systems are based on digital cameras that send video or still images through a local area network (LAN) to a server. Typically digital systems are IP-based. If the LAN is connected to the Internet, the surveillance information may be accessible from anywhere, usually through a secure, encrypted channel. It may also be possible to store the surveillance information in the cloud.
Some digital cameras also have built-in web servers so that external servers are not required. In this case, the surveillance information is transmitted directly to the terminal location for storage or play-back. There are also digital cameras with their own CPU and memory to do onsite preprocessing of the video. This may include object recognition and/or object tracking.