Types of network cameras
Network cameras can be classified in terms of whether they are designed for indoor use only or for indoor and outdoor use. An outdoor camera requires an external, protective housing unless the camera design already incorporates a protective enclosure.
Network cameras, whether for indoor or outdoor use, can be further categorized into fixed, fixed dome, covert PTZ, and thermal network cameras.
Fixed network cameras
A fixed network camera is a camera that has a fixed viewing direction once it is mounted. It may come with a fixed, varifocal or motorized zoom lens, and the lens may be exchangeable on some cameras. A fixed camera is the traditional camera type where the camera and the direction in which it is pointing are clearly visible. This type of camera represents the best choice in applications where it is advantageous to make the camera very noticeable.
Fixed cameras can be installed in protective enclosures. Axis’ outdoor fixed cameras come pre-installed in housings. Fixed cameras can also be mounted on a pan/tilt motor for greater viewing flexibility.
Fixed dome network cameras
A fixed dome network camera is a fixed camera in a dome design. It may come with a fixed, varifocal or motorized zoom lens, and the lens may be exchangeable on some cameras.
The camera can be directed to point in any direction. Its main benefit lies in its discreet, non-obtrusive design, as well as in the fact that it is hard to see in which direction the camera is pointing. The camera is also tamper resistant. Axis’ fixed dome cameras provide different types and levels of protection such as vandal- and dust-resistance, and IP66 and NEMA 4X ratings for outdoor installations. The cameras can be mounted on a wall, ceiling or pole.
A fixed dome with a wide-angle lens and a megapixel sensor that provides a 360° field of view is often known as a panoramic or 360° camera.
Covert network cameras
Covert cameras are designed to blend into the environment and be virtually impossible to discover. They can be placed at eye-level at entrances or integrated into things such as ATM machines for discreet or covert surveillance. They can enable close-up shots for identification purposes or overview surveillance. Tampering risks are also reduced.
Using a pin-hole lens, Axis’ indoor/outdoor covert network cameras provide resolutions of up to 1 MP, including HDTV 720p, and come pre-mounted with an Ethernet cable for both power and data. The cameras are ideal for use in retail stores, banks and hospitals.
PTZ network cameras
A PTZ camera provides pan, tilt and zoom functions (using manual or automatic control), enabling wide area coverage and great details when zooming in. An Axis PTZ camera usually has the ability to pan 360°, tilt 180° or 220°, and is often equipped with a zoom lens. (A zoom lens provides an optical zoom that maintains image resolution, as opposed to a digital zoom, which enlarges an image with loss in image quality.)
PTZ commands are sent over the same network cable as for video transmission (no need for RS- 485 wires as is the case with an analog PTZ camera). PTZ cameras with support for Power over Ethernet (PoE/PoE+/High PoE) also do not require separate power cables, unlike an analog PTZ camera.
PTZ cameras can come in various form factors; the most common is a PTZ dome, which is ideal for use in discreet installations due to its design, mounting (particularly in indoor, dropceiling mounts), and difficulty in seeing the camera’s viewing angle. In outdoor installations, the cameras are usually mounted on poles or walls of a building.
In operations with live monitoring, PTZ cameras can be used to follow a person or object, and zoom in for closer inspection. In unmanned operations, automatic guard tour on PTZ cameras can be used to monitor different areas of a scene. In guard tour mode, one PTZ network camera can cover an area where many fixed network cameras would be needed. The main drawback is that only one location can be monitored at any given time.
Axis’ high-end PTZ domes offer high-speed endless pan, tilt and zoom, and provide mechanical robustness for continuous operation in guard tour mode. PTZ domes with a mechanical stop incorporate Axis’ Auto-flip functionality to enable them to pan 360°.
Some of the features that can be incorporated in a PTZ camera include:
- 3D privacy masking. 3D privacy masking, which is supported in most Axis PTZ cameras, enables selected areas of a scene to be blocked or masked from viewing and recording. It allows masking to be maintained even as the camera’s field of view changes through panning, tilting and zooming since the masking moves with the camera’s coordinate system.
- E-flip. When a PTZ camera is mounted on a ceiling and is used to follow a person in, for example, a retail store, there will be situations when a person will pass just under the camera. When following through on the person, images would be seen upside down without the E-flip functionality. E-flip electronically rotates images 180° in such cases. It is performed automatically and will not be noticed by an operator.
- Preset positions/guard tour. PTZ cameras enable a number of preset positions, normally between 20 and 100, to be programmed. Once the preset positions have been set in the camera, it is very quick for the operator to go from one position to the next. In guard tour mode, the camera can be programmed to automatically move from one preset position to the next in a pre-determined order or at random. Normally up to 20 guard tours can be set up and activated during different times of the day.
- Tour recording. The tour recording functionality in PTZ cameras enables easy setup of an automatic tour using a device such as a joystick to record an operator’s pan/tilt/zoom movements and length of time spent at each point of interest. The tour can then be activated at a touch of a button or at a scheduled time.
- Autotracking. Autotracking is an intelligent video functionality that will automatically detect a moving person or vehicle and follow it within the camera’s area of coverage. Autotracking is particularly beneficial in unmanned video surveillance situations where the occasional presence of people or vehicles requires special attention. The functionality cuts down substantially the cost of a surveillance system since fewer cameras are needed to cover a scene. It also increases the effectiveness of the solution since it allows a PTZ camera to record areas of a scene with activity.
- Advanced/Active Gatekeeper. Advanced Gatekeeper enables an Axis PTZ camera to pan, tilt and zoom in to a preset position when motion is detected in a pre-defined area and return to home position after a set time. When this is combined with the ability to continue to track the detected object, the function is called Active Gatekeeper.
- Electronic image stabilization (EIS). In outdoor installations, PTZ cameras with zoom factors above 20x are sensitive to vibrations and motion caused by traffic or wind. EIS helps reduce the affects of vibration in a video. In addition to getting more useful video, EIS will reduce the file size of the compressed image and thereby save valuable storage space.
Thermal network cameras
Thermal network cameras create images based on heat that radiates from all objects. Images are generally produced in black and white but can be artificially colored to make it easier to distinguish different shades. Thermal images are best when there are great temperature differences in a scene; the hotter an object, the brighter it is in a thermal image.
Thermal cameras are ideal for detecting people, objects and incidents in shadows, complete darkness or in other challenging conditions such as smoke and dust. The cameras are used primarily to detect suspicious activities as thermal images do not enable reliable identification. They, therefore, complement and support conventional network cameras in a surveillance installation. Thermal cameras can be used for perimeter or area protection, providing a powerful and cost-effective alternative to radio frequency intruder detection, electrified fences and flood lights. In the dark, they provide discreet surveillance since there is no need for artificial light. In public areas, thermal cameras can help secure dangerous or off-limit areas such as tunnels, railway tracks and bridges. Indoor uses include building security and emergency management, enabling humans to be detected inside a building, whether after business hours or during emergencies such as a fire. Thermal cameras are often used in high security buildings and areas such as nuclear power plants, prisons, airports, pipelines and sensitive railway sections.
A thermal camera requires special optics since regular glass will block the thermal radiation. Most thermal camera lenses are made using germanium, which enables infrared light and thermal radiation to pass through. How much or how far away a thermal camera can “see” or detect depends on the lens. A wide-angle lens enables a thermal camera to have a wider field of view, but a shorter detection range than a telephoto lens, which provides a longer detection range with a narrower field of view.
A thermal camera’s sensitivity to infrared radiation is expressed as its NETD value (Noise Equivalent Temperature Difference). The lower the NETD value, the better the sensitivity to infrared radiation.
Thermal imaging technologies, which were originally developed for military use, are regulated. In order for a thermal camera to be freely exported, the maximum frame rate cannot exceed 9 frames per second (fps). Thermal cameras with a frame rate of up to 60 fps can be sold within the EU, Norway, Switzerland, Canada, U.S.A., Japan, Australia and New Zealand on the condition that the buyer is registered and can be traced. See thermal cameras product range.