Closed-circuit television
Video surveillance systems are used for observation with optical- electronic devices. In the English -speaking world, these systems fall under the designation of Closed Circuit Television (CCTV ). The term Closed Circuit ( translatable with closed loop or closed conduit ) points out that the images of CCTV cameras can be transmitted to a limited number of receivers. The reference to the "closed pipe " borders one from the CCTV broadcasts from public television, the images can be viewed from a highly visible large audience.
The main use of video surveillance systems is the monitoring of public or private spaces, transport and technical facilities of all kinds
Conventional video surveillance systems consist of at least one surveillance camera and a display monitor, optionally, the systems allow recording the images ( for example, on videotape ), the transmission is analog, wired or wireless.
In modern plants digital cameras that are connected over a TCP / IP network to a computer ( IP camera ) used in the rule. Additional features such as motion detection, face detection and storage of data may be made via special video surveillance software.
- 5.1 The legal aspects
Technology
Since it may be both in a video surveillance system to a simple structure, which consists of only a single camera, the image will be broadcast live on a single monitor, as well as a complex system with multiple cameras and different systems for the storage and analysis of image - or video material, the technologies used are very diverse. A system can be supervised by personnel of the operator or a service provider or work fully automatically after installation. In fully automated systems in which, for example, the live image is not considered, by sampling carried out functional checks and visual material accessed only when needed.
Initially own, analog transmission systems have been constructed by means of coaxial cable, twisted pair technology or analog fiber optic transmission. This technology is indeed common to be far, but is no longer configured in this classic shape due to the ongoing technological progress and the transformation to IP technology for new plants. This is supported by the relative bulkiness and the wear behavior of video cassettes towards digital storage media.
For several years, the transition takes place towards digital CCTV systems. These are available in several variants. For one analog cameras that are connected to a computer, which digitizes a corresponding map the camera signals they represent and can pass over a network. Such hybrid systems are found mainly where analog cameras were already present and not without great effort ( re-wiring ) can be replaced. Secondly, in the exclusively digital version. Here to use IP cameras, for which video is transmitted via a private or public IP network to the monitoring center where they are displayed and / or recorded. The transmission of the video takes place purely on commercial IT systems ( routers, switches, etc.). The challenge in this case is the reliable and safe change (ie forensic grade ) transmission. The change to or the integration of digital technologies therefore poses some advantages ( space requirements of the storage media, image quality) a number of new problems ( memory and bandwidth requirements as well as the variety of formats of techniques for video compression ).
With digital video surveillance systems also allows the operator to choose very flexible, under what circumstances and in what form ( low - or high-definition image, video, possibly with sound ), a record. The camera can even serve as a motion sensor; is a motion in one or more areas pre-defined place, a recording - or even Logging - effected. This serves to reduce the memory requirements and the time needed, which must be invested by the operator in the sighting. The challenge at this point is to avoid Fehlauslöungen by insect and bird flight or just the change of light conditions, without at the same time to miss the actually controlling events. An integration of other sources, such as alarm systems, is also possible.
Most camera sensors are sensitive to visible light (laser light, sunlight, headlights). This results in an unfavorable angle of incidence to over- exposure of the camera image. The latter is not only for outdoors but also for interiors of importance. Sunlight or artificial light falling through a window or a door, can significantly degrade the image of a camera. The software in cameras or recording system can counteract this problem limited to the white balance and individual exposure settings. Often, the problem of glare of a camera, which would result in all or partially exposed images, achieved by the formation of multiple cameras with different angles.
Because of the many possibilities of signal acquisition, processing and recording there is no technological standard for video surveillance systems. Depending on the application and location but must in the selection and installation of video surveillance system by the operators country-specific legal norms are observed and therefore limit the choice. These are also those which do not deal directly with surveillance, but with fire protection and accident prevention.
History
The first television monitoring system was installed by Siemens in 1942 on the test bench VII in Peenemünde to monitor the launch of the A4 rocket.
Applications
Main article: Video surveillance
Public monitoring
Individuals, businesses and governments try by video surveillance equipment in their buildings and grounds from attacks to protect, such as burglary, theft, vandalism and sabotage and to intervene rapidly in case of possible violations or to identify the perpetrators after the fact.
Furthermore, be used by the police in addition to conventional films and photographs mobile surveillance cameras to monitor demonstration participants to identify you personally and to document violations demonstration conditions and laws.
A massive use of video surveillance of public spaces including the EU project INDECT, which started in 2009 and will run for five years. It is through automated analysis of the images of a plurality of cameras " abnormal behavior " be recognized preventive. The data in real time with other, e.g., publicly available data from the internet links, such as from social networks. Suspects are then followed by fully automated flying camera drones. The project has caused massive criticism from various quarters.
Industry
In space technology television monitoring of missile launches, followed by recording assists in the review of rocket flight and makes it easier in the case of failure, the elucidation of the causes. There are both cameras on the ground and in larger missiles on board used the same. Even before the start of the filling process with the help of television technical means for security is monitored.
The interior of nuclear reactors is monitored by means of television surveillance systems, as not or let conventional window made of radiation protection and strength for technical reasons, difficult to implement. Also processes in reprocessing plants are therefore frequently monitored with tv technical means. In addition, the use of CCTV in marine applications, oil drilling platforms has been established for years. The television monitor is used for loading and unloading of ships, but also to security-related surveillance of eg helicopter landings and for protection against piracy.
In the chemical industry, the chemical reactions in containers is often observed with the help of television surveillance systems. This is more convenient and safer than direct observation.
A video monitor also does not come even with all experimental processes in industry and research are used, which are dangerous for human personnel or due to the conditions (duration, sensitivity to light, temperature, atmosphere, etc.) under which they expire, anyway directly or only with massive restrictions may be observed.
Since it is mostly operations and situations outside of the public space, which also usually already run under highly controlled conditions, this type of surveillance plays in the discussion of video surveillance virtually no role.
Software
- ZoneMinder - Open Source