Definitions

Many specific terms and concepts are used in CCTV systems. Below is a list of definitions based on our CCTV HF Guidelines. 

Brightness

Attribute of visual sensation according to which an area appears to emit more or less light (ISO 9241-302:2008; Ergonomics of human system interaction - part 302: Terminology for electronic visual displays).

CCTV System

Closed Circuit Television System A television transmission system in which live or prerecorded signals are sent over a closed loop to a finite and predetermined group of receivers.

Control room

Core functional entity, and its associated physical structure, where control room operators are stationed to carry out centralised control, monitoring and adminis- trative responsibilities (ISO 11064). 

Control room operator

Individual whose primary duties relate to the conduct of monitoring and control functions, either on their own or in conjunction with other personnel both within the control room or outside (ISO 11064-5). 

Control workstation

Single or multiple working position, including all equipment such as computers and communication terminals and furniture at which control and monitoring functions are conducted. 

Depth of field (DoF)

Range of visual focus of images from the distance at which all images are in focus (ISO 9241-302). When you focus on a subject, a certain distance in front of and behind the subject also will be in focus, although not necessarily as sharp. Depth of field increases or decreases based on the focal length of the lens, the distance to the subject, and the aperture. 

Display

Device for presenting information that can change with the aim of making things visible, audible or discriminable by tactile or proprioceptive perception. 

Display, visual 

visual display (in the sense of format) providing visual presentation of data, mappings or videos (NEN-EN-ISO 11064-5) 

Field of view (FOV) 

Related to the human operator: angular region subtending the active area of a display as observed from the viewing direction or other eye position (ISO 9241-302).
Related to cameras: the area of a scene, observed by a camera and lens combination and measured both horizontally and vertically, that can be seen through the camera. f-number The lens aperture, indicated by f-number or f/.. determines the amount of light on the sensor. The f-number is given by the focal length f divided by D (diameter of the effective aperture). 

Frame

One of the many still images that compose a complete moving picture in film, video production, animation and related fields. (2011, APTA). 

Legibility

Ability for unambiguous identification of single characters or symbols that may be presented in a non-contextual format (ISO 9241-302). 

Line of sight

Line connecting the point of fixation and the centre of the pupil (ISO 9241-3). 

Monitoring

Activity for the purpose of detecting deviations from normal operation (by checking variables, or their course against limits, trends or the values of other variables) to enable timely and appropriate action for response (ISO 11064-5) 

Pan and tilt (zoom) unit (PTZ)

A motorized unit permitting the vertical and horizontal positioning of the camera equipment. (sometimes including zoom function) (NEN-EN 50132-7). 

Pixel area

Area made up by x horizontal and y vertical pixels.

Preset shot

A function in pan and tilt units and/or zoom lenses, which allows automatic return to one or more predetermined positions. (NEN-EN 50132-7) 

Readability

Characteristics of a text presentation on a display that affect performance when groups of characters are to be easily discriminated, recognized and interpreted (ISO 9241-302). 

Scene

A scene is a logical and meaningful set of connected and coherent visual information, to be monitored with a specific aim. A scene can consist of one or multiple images. It does not necessarily contain CCTV-images only.

Shared visual display device

On-workstation visual display which needs to be used by more than one control room operator while they are at their control workstations. 

Situational analysis

Task analysis in an existing situation to analyse all the behavioural aspects of the work system, such as revealing practical experiences, informal communication, expectations and complaints of current users and any other facts that might be useful for redesign purposes (ISO 11064). 

Task

Human activities required to achieve a goal (ISO 11064-5) 

Task analysis

Analytical process employed to determine the specific behaviours required of people when operating equipment or doing work (ISO 9241-5; 1998). 

Validation

Confirmation, through the provision of objective evidence, that the requirements for a specific intended use or application are fulfilled. (ISO 11064-7). 

Verification

Confirmation, through the provision of objective evidence that specified requirements have been fulfilled (ISO 11064-7).