IP surveillance: recommendations for selecting and configuring cameras..
IP surveillance: recommendations for selecting and configuring cameras.
Analog cameras are veterans of the CCTV market and occupy leading positions, as they have many useful characteristics: high sensitivity, reliability, proven installation technologies, certain established standards.
IP cameras allow you to shoot, digitize, compress and transmit directly to the network the finished image without delays and interruptions. An IP camera can be connected to the network using a switch or Wi-Fi access point. The advantages of IP surveillance include the ability to get an «endless» archive based on the server, advanced software with many settings and the ability to expand the system without much additional cost. There are many examples of interesting installations using IP cameras, for example, public transport with IP cameras based on internal memory for recording a video stream or the ability to monitor remote objects via satellite Internet, or security of objects with signal transmission via fiber optics.
However, analog cameras will still be present on the CCTV market for a long time — often the quality of the image obtained by analog cameras exceeds the quality characteristics of images obtained by IP cameras. And the cost of analog cameras is still significantly lower than IP. Therefore, it is too early to say that IP cameras will replace analog cameras in the near future.
Since there is already enough information on analog cameras, there are still many questions about choosing and configuring IP equipment. In this article, we will try to expand on this topic a little and consider the key points that need to be taken into account when choosing and configuring IP cameras.
First of all, it is necessary to determine what task the IP camera will have to solve. Will it perform a general overview of the situation at a specific site or will the camera have to identify the vehicle number? Different tasks will require different cameras. Here it is necessary to take into account the camera resolution and the focal length of the lens. For example, to record a car number, you need to choose the right focal length of the lens, and the resolution in this situation will not play an important role. If the camera's task is to monitor the general situation on the territory, then it is advisable to choose a camera with a wide-angle lens and a VGA resolution of about 640×480. But to control cash transactions, it is better to choose megapixel IP cameras. In this case, when choosing a lens, you will need to take into account the location of the camera.
An extremely important issue to consider when choosing an IP camera is its installation location. If the IP camera is located outdoors, you should choose an all-weather model or select special housings for the camera that will protect the IP camera from moisture, dust and ensure the operation of the equipment at sub-zero temperatures. There are special brackets and tripods for mounting indoor cameras; they allow you to mount the camera on a wall or ceiling. In addition, you should consider the possibility of vandalism, and if such cases occur, the camera should be equipped with a special anti-vandal housing.
The next criteria for selecting an IP camera are the illumination of the object and the time of day when surveillance is required. If the illumination level of the object where you plan to place the IP camera is unstable, it is best to choose a camera with a wide dynamic range — it allows you to get high-quality images even in darkened areas of the object. Here, it is best to choose a lens with an auto iris, and choose a camera with IR illumination — the optimal solution for round-the-clock surveillance. And, of course, you need to consider the light sensitivity of the camera — for well-lit objects with a constant level of illumination and for an area in which there are darkened areas and the lighting changes — the light sensitivity characteristics differ significantly.
Next, let's focus on the image quality of the IP camera. It is determined by the quality of the camera components, namely:
— matrix light sensitivity
— lens
— compression codec
The image quality of the matrix is determined by the resolution, sensitivity, color rendering, etc. The resolution of light-sensitive matrices is divided into standard VGA (640×480) and megapixel (1,2,3 megapixels). The higher the resolution, the better and more detailed the image.
Recently, the share of megapixel cameras has been rapidly increasing, since the image quality obtained as a result of such cameras is higher. A separate niche for megapixel cameras should be allocated to options for systems with a huge resolution. At the moment, this is the only way to get a wide-format informative frame with digital signal processing. The image quality is striking in its scale and resolution.
Matrices are divided into CCD and CMOS according to manufacturing technology. Traditionally, CCD matrices were used in analog cameras, and CMOS were most widely used in IP cameras.
CCD matrices have excellent sensitivity, provide good color rendering, and are equipped with a wide dynamic range function. The only disadvantage of such matrices is the impossibility of obtaining such a high resolution, which is provided by IP cameras. CCD matrices with megapixel resolution have already appeared on the market; they combine all the positive characteristics of CCD matrices, but their price is still much higher than the cost of cameras with a CMOS matrix.
The advantage of CMOS is their low cost, so manufacturers offer many inexpensive megapixel cameras based on them. Previously, the quality of CMOS matrices was quite low, but over the past couple of years, the breakthrough in this area is quite impressive. The color rendering in them has already become equal in quality to the quality of CCD matrices, sensitivity has improved and noise has decreased.
However, it is difficult to choose a camera based on technical characteristics alone, so it is best to take the camera for a test drive or watch the DEMO version of the camera's online operation on the suppliers' website.
Next is the camera lens. If chosen correctly, it ensures high image quality. Unfortunately, some unscrupulous manufacturers install a low-quality lens on the camera to reduce its cost, which worsens the image quality. Therefore, you need to select a lens with the help of a specialist. It is worth considering that a megapixel camera requires a megapixel lens.
Encoder. The resulting image is transmitted over the network for further processing. There are pitfalls here too. Frame-by-frame compression format (MJPEG encoding) does not require a powerful processor and perfectly preserves detail, but at the same time creates a heavy load on the network. MJPEG encoding is usually used to solve specific problems — where it is necessary to present video recording in separate frames (for example, when determining car numbers). Inter-frame compression (MPEG-4 and H.264) allows you to transmit large amounts of video over the network without overloading it excessively, but requires a large amount of processor resources. MPEG-4 encoding is gradually being replaced by the H.264 codec, which contains a number of new features that allow you to significantly increase the efficiency of video compression compared to previous standards and provide greater flexibility of use in various network environments. Thanks to H.264, much fewer network resources are used to transfer files, which allows you to significantly improve image quality while maintaining the same transfer rate.
To obtain a high-quality image, the IP camera must be configured correctly. For each IP camera, you need to adjust the white balance, brightness and contrast. If everything is more or less clear with brightness and contrast, then the white balance should be discussed separately. This function allows you to adjust the quality of color rendering at any time during observation, while the sensitive matrix of the IP camera adjusts to the illumination of different areas of the object.
When choosing IP cameras, it is important to pay attention to the flexibility of camera settings and the ability to remotely configure the main parameters. It is advisable to choose cameras with a ZOOM lens — they provide the ability to remotely focus, which will significantly improve the image quality. High-speed IP cameras also have this function.
So, in order to obtain the optimal image quality, you need to consider the following:
1. Determine what task the IP camera is to solve: is image detail required or is a general overview of the object sufficient
2. Complete the camera according to the location where it will be installed — indoors or outdoors, whether vandal-proof or thermal protection is required.
3. Illumination of the object where the camera is planned to be installed and selection of cameras with the appropriate sensitivity.
4. Light-sensitive matrix — depending on the installation location and illumination of the object, choose a camera with a CCD or CMOS matrix, but first consult with a specialist.
5. It is extremely important to choose the right quality lens. Here, you will also need the help of a specialist in the installation and assembly of video surveillance systems.
6. Encoding. If the task is frame-by-frame image transmission, then you should choose MJPEG encoding. In all other cases, you should use the H.264 standard
7. Camera settings – white balance, brightness and contrast, as well as the ability to make remote settings.
In addition, when selecting IP cameras, an important place is occupied by software (which determines the reliability and stability of the video surveillance system), the number of simultaneously operating cameras, the ability to remotely connect to the server with the archive.
If the video is to be transmitted over the Internet, it is worth considering the possibility of making adjustments to optimize the quality for a certain transmission speed.
There are situations when there are no communication lines at some sites. In principle, none. A system based on wireless Wi-Fi is ideal here, including the possibility of remote access, control, route settings (for PTZ cameras) and adjustments to the system as a whole.
The most promising and cost-effective solution is to install IP cameras in an already existing local network of the facility. Some networks are designed in such a way that they simply do not provide the opportunity to organize the installation of a video surveillance system. But in most cases, if there is a developed local network, all that remains is to install the cameras and combine them into a common network. This requires minimal costs of both time and money.
Next, using the wide range of image quality settings, we get the desired traffic without completely loading the network.
Let's summarize: a new generation of video surveillance based on digital technologies is becoming available not only in terms of pricing policy, but also takes into account the level of training of the user, the customer. Quite recently, highly qualified engineers and service personnel were required to organize a video surveillance system based on IP solutions. Today, we can confidently say that digital technologies have entered every home and, above all, people's minds.
Ivan Podgorny, specialist in the technical department of Acumen Int. Corp.