The most important ingredient in a closed circuit television (CCTV) solution is the camera. It is the source of information that feeds into the CCTV ecosystem and is the start of the image journey to the video management system (VMS) and the intelligent video analytics (IVA) platform, and the mass storage solution. Without the camera, it is all for not.
Yet, the camera is often treated as the commodity item and not given the respect that it deserves as a key component of the end to end system.
It is not surprising to see the cheapest cameras connected to the most advanced and expensive headend systems. Then, when the users complain about poor performance due to resolution or low light capabilities, they seem perplexed as to the cause.
The selection of the ideal cameras is critical to the overall performance of the CCTV solution.
Some of the technical criteria that is essential to selecting the right cameras includes:
- Chip properties: CCD or CMOS
- Chip size
- Image resolution
- Lens
- CPU power for metadata
- Housing and environmental characteristics
- Protocols and standards
- Form factor
- Digital capabilities
- Installed location
- View geometry
- Cabling and installation craft skills
- Infrared capabilities
- Encryption and security capabilities
- Tamper proof and detection
- Discreet or covert capabilities
- Lighting conditions
- Fixed versus pan/tilt/zoom
There are literally thousands of camera models from hundreds of approved manufacturers available in the market, and this makes the selection of the most appropriate CCTV camera to use a very confusing issue. It is all about ‘fit’. Finding the right CCTV cameras that best fit your technical requirements. It is not about which one has the most ‘bells and whistles’ or which model is the most expensive. It is about the fit for the purpose of the application. Since the camera is perhaps the most important element in the CCTV solution, it warrants you to take the time and make the effort to reduce the option s list down to the level whereby you can short-list 3-4 vendors.
Sensor chip properties: CCD or CMOS
The image sensor is the core component of any camera. Conventional analog cameras adopt interlaced CCD image sensor to capture standard definition images, while recent network cameras utilize progressive scan CMOS image sensor to deliver high definition images. The quality of image sensor determines the camera’s imaging capability and performance. In this article, we intend to give you some basic information about image sensor.
Image sensor is the “eye” of your security camera. An image sensor is a device that converts an optical image to an electric signal. It is used mostly in digital cameras and other imaging devices. An image sensor is typically a charge-coupled device (CCD) or a complementary metal–oxide–semiconductor (CMOS) active-pixel sensor.
CCD and CMOS image sensors are two different technologies for capturing images digitally. Both types of imagers convert light into electric charge and process it into electronic signals.
CCD is the abbreviation of Charge Coupled Device, is a device for the movement of electrical charge, usually from within the device to an area where the charge can be manipulated. To integrate with a sensor, such as a photoelectric device to produce the charge that is being read, thus making the CCD a major technology where the conversion of images into a digital signal is required.
CMOS stands for Complementary Metal-Oxide Semiconductor, also known as active-pixels sensors. CMOS sensor descends from the MOS activepixel image sensor which was invented in the 1960s. Contains integrated circuitry, arrays of pixel sensors.
No matter how good CCD is, or how fast development of CMOS technology, CCD imaging technology is still monopolized by Japanese companies (Sony, Panasonic, Sharp etc). For high definition security cameras, American companies control the video processing, video compression and transmission technologies. Therefore, first developed high definition network cameras adopts CMOS image sensor developed by Texas Instrument. Additionally, CMOS sensors are much less expensive to manufacture than CCD sensors. To manufacture CMOS image sensor require a total different manufacturing infrastructure. In the past years, CCD image sensor manufacturers were reluctant to abandon CCD sensors manufacturing. More and more security companies choose to develop network cameras equipped with CMOS image sensors.
Sensor chip size
In theory, bigger pixels on full-HD CCD image sensors are better for global security applications because they are more sensitive for improved low light performance. The drawback is that bigger optics are required so size, weight, power, and cost requirements are challenged. As many systems are upgrading from standard definition to full-HD cameras or adding HD daylight cameras for full motion video, the question is how to find the optimal balance.
High-end applications, such as long range targeting or in very low light, which are moving to full-HD resolution will still require 2/3” sensors. Over the last few years, there have been dramatic improvements in Qe and read noise of image sensors to make 1/2” full-HD sensors with the sensitivity required for many applications. In parallel with the sensor improvements, there have been many developments in 1/2” long focal range optics and zoom optics as a necessary complement.
For upgrades, this provides the option to use the same optical format, but have more pixels and more sensitivity. This can be a cost-effective approach although new optics are still required.
Not all of the 1/2” optics available meet the full MTF so the camera provides a better image quality than the lens. The resulting image might not have the sharpness required by high-end applications. The optics are getting better and better though.
To use smaller and even lower cost optics, it is attractive to go below the 1/2” sensor size, for instance 1/3” CCD image sensors. Not only does the image sensor performance go down, but the available optics quality also decreases.
1/3” CMOS image sensors can offer good low light performance, but 1/3” CMOS sensors utilize a rolling shutter as compared to global shutter available in CCD and larger CMOS image sensors. Currently rolling shutter is not well received in the industrial and military applications as a blurring effect occurs with movement. Global shutter CMOS is more complex and will take further development to shrink for smaller pixels.
For now, 1/2” image sensors provide a sweet spot for many global security applications with acceptable sensitivity and the ability to use small, low cost optics. For more demanding applications, 2/3” image sensors may be required.
Image resolution
In IP cameras, this is determined by number of pixels (color dots) that each camera image consists of. The higher the image resolution, the more image details is captured and provided by the camera. At the same time, more storage capacity would be required for recording. The current common resolutions these days start from 720p HD (1280 x 720 pixels) and go up to 5MP (5 Megapixel or 2592 x 1944 pixels).
Most CCTV cameras used worldwide today are still analog cameras. As a result, one high definition camera can do the job of 4-6 older analog cameras. The savings with TCP/IP cameras are found in the installation, fewer mounts, less cabling, lower maintenance, and superior image quality to name few benefits.
Lens
The type of lens determines the angle width and the distance that each camera can cover. As a rule of thumb, the wider the coverage angle is, the less distance is covered by the camera. Using a vari-focal lens enables you to adjust these two parameters of the camera in practice. There are also 180 degrees or 360 degrees fisheye cameras that are used indoors for providing a wider coverage.
CPU power for metadata
There is a new generation of CCTV video cameras that do much more than just generate endless streams of video content. These next generation cameras have a CPU inside them along with memory and other capabilities. Effectively, they have built-in computers inside. These computers can do many things, such as generate metadata, run algorithms, and store and forward content.
What is metadata?
“Metadata” is a term used to describe data that informs us about other data. In surveillance terms, it is the data relating to changes in a video stream. Metadata provides identity and context to events in the digital video stream, allowing the video to be organized, searched and retrieved easily.
“Machine understandable”
Digital video content is inherently unstructured and difficult to search. Machines cannot “watch” video and interpret it like a human. However, metadata uses identifiers to inform a computer what it is “watching”. Identifiers are absolute, measurable and scalable facts or events. They can include time, location and other application-specific attributes. They enable a machine to analyze content for changes and trends and search for specific types of event. Metadata makes video data “machine-understandable”.
Intelligent Surveillance
An intelligent video surveillance system with metadata capabilities can be used to exchange analyzed information. The metadata is effectively index a very large video surveillance databases and that can help perform unified searches and management between distributed or heterogeneous surveillance systems more efficiently. The system consists of low-level context-aware, high-level context-aware and intelligent services to generate metadata for the surveillance systems. Various contexts are acquired from physical sensors in monitoring areas for the low-level context-aware system. The situation is recognized in the high-level context-aware system by analyzing the context data collected in the low-level system. The system provides intelligent services to track moving objects in Fields Of View (FOVs) and to recognize human activities. Furthermore, the system supports real-time moving objects tracking with Panning, Tilting and Zooming (PTZ) cameras in overlapping and non-overlapping FOVs.
Metadata and security
Metadata offers three significant security surveillance functions – search, alert/alarm and reporting. Metadata adds context to each digital video frame and the objects, vehicles and people within it, including:
- Date and time
- Camera obstructions
- Scene motion
- Camera movement
Metadata allows digital video information to be far more “searchable” by defining:
- Object identity
- Object size
- Object time in view
- Object type e.g. car, person, train etc
- Object movement
- Object size in a scene
- Object location in a frame
- Vehicle license plate numbers
Security management functions use these specific triggers to identify incidents and events. Rules can be set up, such as ‘virtual fences’, trip wires and people counting, to help understand the interactions objects have with their environment. A scene can be learnt over a period of time and normal object movement (or lack of movement) tracked within that scene. “Normal” or “abnormal” events can be recognized against a defined set of rules, with only the changes in a scene being registered, not the entire scene.
Camera Housing
The camera housing is also an important factor to consider when selecting your camera. Below are the main types:
- Dome Cameras: Dome cameras are used both for indoors and outdoors for both fixed and PTZ cameras. They have a nice look and it is also hard to determine which direction the camera is pointing at.
- Box Cameras: These cameras are also used both indoors and outdoors and are the standard type of security cameras we all have an image of in mind. The lens and direction of the cameras are clearly visible and clearly show everyone that the location is under CCTV surveillance.
- Bullet Cameras: These are small, cylindrical type, waterproof housings that are usually used for outdoor cameras especially when you don’t want the cameras to capture much attention.
Environmental Characteristics
One of the parameters that can be easily filtered by available choices is whether the camera is for indoor or outdoor use. While it is essential to use an “outdoor” type camera for outdoor installations to provide IP65/IP66 weather protection, “indoor” cameras are less bulky and more cost effective for indoor installations.
New housings and cameras can offer vibration reduction to mitigate the local vibrations from road traffic, train vibrations at freight, logistical and rail-yards, on board ships at sea, or even in factories with heavy machinery active such as stamping machines. All of these sources can disrupt camera signals with microphonics that cause the camera’s internal clocking oscillator to become unstable creating a loss of signal or affect the camera image so as t result in image distortions.
In Canada and other countries with extreme temperature swings throughout the year, the ability for the CCTV camera to operate in varying climate from -45 °C to +50 °C (-50 °F to 122 °F) is imperative. Housings that resist salt water spray in coastal regions is critical too.
While it is important to keep temperature in mind, it is actually relative humidity that can play a bigger factor in equipment failure.
For example, if you were to install a dome camera during the summer months in an environment with high relative humidity, it could potentially build up condensation on the dome during the cooler winter months and block the camera’s view. This is especially true in locations in which the temperature changes very fast.
To help compensate for this issue, camera manufacturers put in a fan in the device so air will continuously circulate. This prevents a stagnant environment so water will not condensate on the dome.
What IP68 means to you: With a IP68 camera housing you get the ultimate protection for your security camera and security camera equipment keeping dust, debris, insects, and water outside the enclosure. A camera that meets IP68 will tolerate submersion and remain watertight up to two metres below the surface. This is important for flood prone areas light underground subway stations.
Protocols and standards
ONVIF: Open Network Video Interface Forum
The core ONVIF specification, which was launched in November 2008, aimed to define a common protocol for the exchange of data between network video devices. Since then it has extended its scope to include access control products and also has developed specialist profiles for specific categories. The idea behind the profile was to help end-users identify which version of the ONVIF specification the products they were interested in conformed to, making it easier to determine compatibilities between conformant products and specific interoperability features.
There are now three ONVIF profiles, S, G, and C. Profile S looks at the common functionalities of IP video systems, Profile G addresses storage and recording functionalities and Profile C, the integration of IP-based security and safety devices, including access control units. Profile C is expected to be released in early 2014.
PSIA: Physical Security Interoperability Alliance
PSIA is smaller in number, being made up of 65 physical security manufacturers and systems integrators. Nevertheless it aims to make its reach very broad. It has five active working groups, namely: IP Video, Video Analytics, Recording and Content Management, Area Control, and Systems.
Comparisons with other groups such as between ONVIF and PSIA are difficult because the approaches are quite different. The industry participation that ONVIF has achieved speaks for itself. Specifically, ONVIF excels with its web services architecture and strong legal framework as well as its decision to establish an underlying specification and then tackle each discipline, such as video or access control or intrusion, individually.
H.264 / MPEG-4, Part 10 / AVC
H.264 or MPEG-4 Part 10, Advanced Video Coding (MPEG-4 AVC) is a block-oriented motion-compensation-based video compression standard. As of 2014 it is one of the most commonly used formats for the recording, compression, and distribution of video content. It supports resolutions up to 8192×4320, including 8K UHD.
Installed location
Camera placement is critical. Yet, we often see misplaced cameras that do not provide adequate coverage of the area to be surveilled. Why is this the case? Often, we hear that it would cost extra to position the camera in the ideal location as it might mean a few extra hours of installation worker time to do it. But, this is a fool’s game to not do it right the first time. A few dollars upfront can pay dividends for a decade or more later. What if a perpetrator could have been caught if a proper facial image was obtained but could not since the camera was installed in the wrong location?
Positioning the cameras at the best site is essential. No corners should be cut in this regard. This issue is normally seen when CCTV cameras are added to existing buildings and properties. On all new builds, it is not the case and with proper planning, CCTV can be well positioned.
View geometry
Different lenses on different sized CMOS sensor chips inside CCTV cameras will give different angles of view for the camera coverage. It is important to calculate all of the camera look angles in advance to ensure that adequate coverage is provided.
Calculating the field of view
How wide a field of view can we see and still be able to identify a person’s face? To calculate the widest field of view, divide the number of horizontal pixels (available from the camera) by the pixels/ft. you would like to achieve. The following formula is used to determine the field of view:
Total Horizontal Resolution / Pixels per ft. = Field of View
For the following example, let’s assume you would like to identify the face of a person you already know. If the camera resolution is 1920 x 1080 pixels (2-megapixel), then our widest field of view is:
1920/80 = 24 ft. (7.3 m).
If we have a 5-megapixel camera with a resolution of 2592 x 1944, then the widest horizontal field of view is 32.4 ft. (9.9 m). And, a 10-megapixel camera, with 3648 x 2752 pixel resolution, provides a 45.6 ft. (14 m) field of view.
We can also do this calculation in reverse. We can start with the field of view and then calculate the resolution of the camera. Use the following formula to calculate the resolution of the IP camera:
(Field of View) x (pixels/ft.) = Horizontal Resolution
If we want a field of view of 20 ft. and we need 80 pixels/ft. then the formula indicates:
20 ft. x 80 pixels/ft. = 1600 pixels (horizontal)
We can now select a camera that has at least 1600 horizontal pixels. For example the Sony SNC-EM630 IP camera has a resolution of 1920 x 1080 pixels. This is a very nice 2.0 mega-pixel camera with enough resolution to meet these requirements. It is also one of the newer IP camera models that provides excellent low light sensitivity and wide dynamic range (WDR).
Cabling and installation craft skills
Day / Night Infrared capabilities
If you require capturing video in darkness, then you should look for cameras with day/night and IR (infrared) lighting configurations. IR cameras use infrared LEDs that are lit automatically when dark and enable the camera to capture black & white video in complete darkness. The coverage of cameras in the darkness is determined by the power of their IR light which is a parameter you should look into when selecting such cameras.
A key point that is often overlooked with IR cameras is that they still require a source of illumination to light the shot. The source of illumination is often built into the camera itself, but to provide proper coverage for a scene, additional IR illumination may be necessary to provide adequate lighting for the scene.
All light exists on a well known scale with visible light in the 400 to 750 nanometer (nm) range and infrared existing in the spectrum greater than 750 nm range.
Encryption and security capabilities
Any camera, whether wired or wireless, as well as supporting infrastructure such as DVR/NVR/VMS should have a firewall for protection, especially if you are going to expose it to the internet for any type of remote access.
Firewalls can be very complex, with thousands of rules. The next generation firewalls are even more complex because they analyze the protocols going over the ports and verify that proper protocols are being used.
A surprising number of cameras use connections which are not encrypted with SSL or equivalent. This risk would be identical to logging into a bank or doing online shopping without HTTPS. It creates password vulnerability and allows potential for privacy and eavesdropping breaches.
Tamper proof and detection
Apart from indoor/outdoor type of cameras, you might also want to select “vandal-resistant” cameras that come with very-hard-to-break glass covers to protect the camera against vandalism. There are also explosion-proof cameras that are extremely expensive and protect the camera against explosions.
Many of the advanced housing have Internet of Things (IoT) sensors built into the unit and this sensor will send a message to the operator when something goes wrong, such as impact detection from a baseball bat or unauthorized attempts to open the housing.
Discreet or covert capabilities
Discreetly monitor your location with our hidden security cameras. Covert CCTV cameras include models that can blend into their surroundings like the sprinkler, smoke detector, and motion detector spy cameras as well as pinhole cameras that can be installed inside of other objects and be virtually undetectable. Hidden security cameras are an excellent choice when you have to monitor an area without anyone knowing they’re on camera. Pair these covert cameras with audio surveillance equipment for a 360° covert monitoring solution.
Lighting conditions
Lighting for your CCTV pictures is crucial. So why is poor lighting so commonplace in CCTV systems? CCTV pictures all begin when light or infrared (IR) hits the camera’s sensor. IR is the same as light but its longer wavelength is outside our eyes’ visible range so we call it invisible. Cameras, however, generally can see both.
Rainbows show all colours humans can see. Violet/blue are short wavelengths of around 400nm (nanometers: billionths of a meter) progressing across the rainbow spectrum to red at around 700nm. We are most sensitive to green light; less so to blue and red. The standard graph of this is the ‘photopic curve’.
This is built into light meters (measuring ‘lux’) so figures are meaningful when we’re designing environments for human eyes.
For instance, sunny days may be 30,000lx, dropping to 500lx in an office, and only 5lx street lighting.
Incidentally, because IR is beyond human visibility your lux meter is, by definition, completely insensitive to it. Be aware that sellers of “zero lux” CCTV might deliver nothing more than a camera which is simply IR-sensitive, like many others.
Cameras’ sensors respond to a wider range of wavelength than our eyes. Much sensitivity is in the infrared region.
However, for realistic colour video this IR needs to be suppressed so an IR-cut filter is put over the chip.
Fixed versus pan/tilt/zoom
PTZ (Pan-Tilt-Zoom) cameras as the name suggests give the possibility to user to turn the camera view to any needed direction and to zoom on specific areas. They can be also pre-programmed to automatically scan specific routes. On the other hand, fixed cameras provide constant uninterrupted monitoring of a specific, fixed area like entrances and exits or perimeters.
One of the most important parameters in selecting the correct type of camera is to determine the coverage area and target distance for each camera in your system.
There you have it. It is likely that I missed some technical parameters, but this is a good start to comprehensively audit the CCTV camera options. It is worth the time and effort to get this all right upfront as the complications to address these issues after the fact will be expensive and take time.
References:
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About the Author:
Michael Martin has more than 35 years of experience in systems design for broadband networks, optical fibre, wireless and digital communications technologies.
He is a Senior Executive with IBM Canada’s GTS Network Services Group. Over the past 13 years with IBM, he has worked in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He was previously a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN: TSX).
Martin currently serves on the Board of Directors for TeraGo Inc (TGO: TSX) and previously served on the Board of Directors for Avante Logixx Inc. (XX: TSX.V).
He serves as a Member, SCC ISO-IEC JTC 1/SC-41 – Internet of Things and related technologies, ISO – International Organization for Standardization, and as a member of the NIST SP 500-325 Fog Computing Conceptual Model, National Institute of Standards and Technology.
He served on the Board of Governors of the University of Ontario Institute of Technology (UOIT) and on the Board of Advisers of five different Colleges in Ontario. For 16 years he served on the Board of the Society of Motion Picture and Television Engineers (SMPTE), Toronto Section.
He holds three master’s degrees, in business (MBA), communication (MA), and education (MEd). As well, he has diplomas and certifications in business, computer programming, internetworking, project management, media, photography, and communication technology.