Camera types

3.1.5 Camera types

Video security cameras are represented by several generic forms including: (1) Analog, (2) Digital, (3) Internet, (4) LLL (low light level), and (5) Thermal IR, (6) Panoramic 360Camera. For daytime applications, monochrome, color, analog, digital, and IP cameras are used. When remote surveillance is required an IP camera is used. For low light and nighttime applications the LLL ICCD (low light level intensified charged coupled device) image intensified camera is used. For very low light level or no light level applications, thermal IR cameras are used.

3.1.5.1 Analog

Analog cameras have been with the industry since the CCTV systems has been used in security. Their electronics are straight forward and the technology is still used in many applications [4].

Figure 3. 5 the back light compensation effect

25

3.1.5.2 Digital

Since the second half of 1990s there has been an increased use of DSP in cameras.

It significantly improves the performance of the camera by:

(1) Automatically adjusting to large light level changes (eliminating the automatic-iris)

(2) Integrating the VMD into the camera

(3) Automatically switching the camera from color operation to higher sensitivity monochrome operation, as well as other features and enhancements.[4]

3.1.5.3 Internet

The most recent camera technology advancement is manifest in the IP camera. This camera is configured with electronics that connects to the Internet, WWW network through an Internet service provider (ISP). Each camera is provided with a registered Internet address and can transmit the video image anywhere on the network. This is really remote video monitoring at its best! The camera site is viewed from anywhere by entering the camera Internet address (ID number) and proper password. Password security is used so that only authorized users can enter the website and view the camera image. Two-way communication is used so that the user can control camera parameters and direct the camera operation (pan, tilt, zoom, etc.) from the monitoring site [4].

3.1.5.4 Low-Light-Level Intensified Camera (LLL)

When a security application requires viewing during nighttime conditions where the available light is moonlight, starlight, or other residual reflected light, and the surveillance must be covert (no active illumination like IR LEDs), LLL intensified CCD cameras are used. The ICCD cameras have sensitivities between 100 and 1000 times higher than the best solid-state cameras. The increased sensitivity is

26

obtained through the use of a light amplifier mounted in between the lens and the CCD sensor. LLL cameras

Cost between 10 and 20 times more than CCD cameras.

3.1.5.5 Thermal Imaging Camera

An alternative to the ICCD camera is the thermal IR camera. Visual cameras see only visible light energy from the blue end of the visible spectrum to the red end (approximately 400–700 nanometers). Some monochrome cameras see beyond the visible region into the near-IR region of the spectrum up to 1000 nanometers (nm).

This IR energy, however, is not thermal IR energy. Thermal IR cameras using thermal sensors respond to thermal energy in the 3–5 micrometer (µm) and 8–14m range. The IR sensors respond to the changes in heat (thermal) energy emitted by the targets in the scene. Thermal imaging cameras can operate in complete darkness. They require no visible or IR illumination whatever. They are truly passive night time monochrome imaging sensors. They can detect humans and any other warm objects (animals, vehicle engines, ships, aircraft, and warm/hot spots in buildings) or other objects against a scene background [4].

3.1.5.6 Panoramic 360 Camera.

Powerful mathematical techniques combined with the unique 360 panoramic lens have made possible a 360 panoramic camera. In operation the lens collects and focuses the 360 horizontal by up to 90 vertical scene (one-half of a sphere, a hemisphere) onto the camera sensor. The image takes the form of a “donut” on the sensor (Figure 3.8). The camera/lens is located at the origin (0). The scene is represented by the surface of the hemisphere. As shown, a small part (slice) of the scene area (A, B, C, D) is “mapped” onto the sensor as a, b, c, d. In this way the full scene is mapped onto the sensor. Direct presentation of the donut ring video image onto the monitor does not result in a useful picture to work with. That is

27

where the use of a powerful mathematical algorithm comes in. Digital processing in the computer using the algorithm transforms the donut-shaped image into the normal format seen on a monitor, i.e. horizontal and vertical. All of the 0 to 360horizontal by 90vertical images cannot be presented on a monitor in a useful way – there is just too much picture “squeezed” into the small screen area. This condition is solved by computer software by looking at only a section of the entire scene at any particular time. The main attributes of the panoramic system are:

(1) Captures a full 360 FOV (field of view), (2) can digitally pan/tilt to anywhere in the scene and digitally zoom any scene area, (3) Has no moving parts (no motors, etc. that can wear out), and (4) multiple operators can view any part of the scene in real-time or at a later time. The panoramic camera requires a high resolution camera since so much scene information is contained in the image. Camera technology has progressed so that these digital cameras are available and can present a good image of a zoomed-in portion of the panoramic scene. The figure 3.6 show the panoramic camera concept.

Figure 3. 6 panoramic camera

28