Security knowledge: What is a panoramic camera

A panoramic surveillance camera is a camera that can independently realize large-scale non-dead-end surveillance. It generally has a 360-degree panoramic view angle, so a panoramic camera can theoretically replace multiple common surveillance cameras for seamless monitoring. The purpose of use. Based on the usage characteristics of the panoramic camera, what are its usage scenarios? Summarized, usually include the following application requirements.

1, only need to monitor the global scene monitoring, no need to identify the details of the scene. Such as train station waiting room, airport terminal and other large-scale public places. Under normal circumstances, these places are open-minded, occupy a larger area, some of the width of more than 100 meters. Monitoring in such a wide range of scenes, while seeing the panoramic image, it is impossible and incapable to see the details in the image. Considering the applicability of the project, only one or a few fisheye cameras can be used for these scenes to satisfy the panoramic monitoring in a venue.

2. In important monitoring situations, full coverage and no dead angle monitoring applications must be implemented. Examples include banking outlets, supermarkets and convenience stores, hotel lobbies, etc. In places where accidental safety incidents are prone to occur, it is not only necessary to monitor the whole process of the suspect's entire crime, but also to pay attention to the fact that each individual is different from any other individual's details.

3. Further, based on the full coverage of surveillance images, it is necessary not only to monitor the overall situation, but also to monitor the details of the scenarios, such as outdoor plazas with higher security levels, campuses, or densely populated places.

It can be seen that, as a subdivided product line of front-end surveillance cameras, the panoramic camera still has its own characteristics and irreplaceable application value, and therefore it has always been an integral part of the video surveillance front-end. So since the panoramic camera has its own unique advantages, how does it differ from the technical realization point of view?

Wide Angle Fisheye Panoramic Camera

Generally speaking, the technical realization of panoramic images can be divided into two types. First, a single sensor is combined with a special super-wide angle fisheye lens to shoot a panoramic image, and then a distortion-reduced panoramic image is restored to a normal image through an image correction technique. Methods. This kind of product can achieve panoramic shooting effect because only one fisheye lens is used on the hardware, so its excellent cost performance makes it occupy half of the panoramic camera market. However, the particularity of the convex surface of the fisheye lens will inevitably result in the waste of the sensor pixels, and the distortion of the screen will hardly reach the nominal high-resolution effect. Therefore, the high-resolution presentation of the monitoring image is also limited to some extent. The technical method to deal with the single fisheye lens image is to use trapezoidal correction image processing technology, and strive to eliminate edge distortion as much as possible.

The fisheye lens is one of the simplest and most effective methods for building panoramic vision. Its outstanding feature is that it can take in all the information in a viewing angle of more than 180 degrees at a time, so as to achieve a no-blind area effect. In terms of characteristics, the fisheye lens is a special ultra-wide-angle lens. The front lens of this lens has a diameter of a parabolic shape and protrudes toward the front of the lens. The visual effect is similar to that of fisheye observation of the water surface. It is a short focal length lens, generally focal length between F = 6-16mm, according to the principle of optical imaging, short focal length can show the effect of monitoring the large field of view.

Multi-shot panorama camera

The second is that multiple sensors are combined with multiple lens combinations to achieve the panoramic function. This type of multi-shot spliced ​​panoramic images are conventional rectangular images. Therefore, it is not necessary to perform special correction, but it is necessary to splicing several monitoring images. Into a panoramic image, this method has strict requirements on the field of view of the lens and the installation position, and because the hardware mostly uses multi-lens and multi-sensor methods, the cost of such products is higher and the price is generally higher. A panoramic camera for single fisheye lens. However, it can cope with a wider range of area monitoring, especially when combined with a multi-lens panoramic camera and a traditional large-scale PTZ camera, it can achieve a multiplier effect.

Panoramic surveillance camera installation

The installation and construction conditions of the panoramic network cameras are similar to those of conventional surveillance cameras. Due to the requirements of ceiling mounting and wall mounting, the following points need to be taken into consideration when cooperating with the environment:

1. Avoid ceiling fixtures

The panoramic network camera should avoid close to ceiling lamps or chandeliers above the ceiling installation. The panoramic camera has strong light in the foreground, and it easily diffuses the light and light fields into a single curved image. Although the panoramic camera has wide dynamic (WDR) and strong light suppression (BLC) functions, it is often under wide dynamic and backlight motions. The brightness of the edges of the image will be less than the effect of no bright light; and the starting transformer frequency of the lamp is often the culprit of the interference of the camera image signal, and this situation should be avoided as much as possible.

2. Ceiling installation to be centered

The ceiling position of the panoramic network camera should be located as far as possible in the central position of the monitoring space. Since the panoramic surveillance camera can restore the image stretching to 2-4 or more plane images after capturing, if the camera installation position is not centered, the restored image will have an edge image asymmetry, and there will be a focus monitoring area offset. Case.

3. Avoid air conditioning vents

Panorama network cameras should be installed without installing them on the edge or in front of the air conditioning vents. In past experience, everything was operating normally after installing a panoramic camera in the winter, but in the summer, the group of panoramic cameras will produce camera lenses after 10 a.m. The misty condition is caused by the front of the air conditioning unit.

4. Avoid the indicator

The panoramic camera should avoid the front of the emergency exit lighting fixture and the red indicator light of the fire box in front of or above the emergency exit lighting fixture. The panoramic camera has these lights in the foreground, and it is easy to spread the lighting optical domain into a tune image. Affects the clear effect of image monitoring.

5. Powered by PoE

The panoramic camera should use PoE power supply as much as possible because the aesthetic treatment of a single cable is simple and easy. If a DC power supply is used, the power supply and the line must be pre-installed during the installation. Otherwise, the decoration will be damaged. In the follow-up maintenance, if the power supply device fails, it has to destroy the decoration, which is quite unfavorable to the maintenance cost.

6. Fix with expansion screws

When the panoramic camera is installed on the ceiling of the mineral fiber, it must be fixed with an expansion screw. It cannot be fixed with ordinary screws. In order to isolate the electromagnetic interference in the ceiling, the panoramic camera has a considerable weight. If it is fixed on the ceiling, it is not fixed by an expansion screw, and there is no pre-installed safety cable. After the project is completed for a period of time, the camera will fall. .

7. Avoid exit gates

The installation position of the panoramic network camera should be avoided at the top of the entrance door. If the camera is installed above the electric door or in front of the door, the camera window will produce condensation drops due to the temperature difference, which will affect the video monitoring effect.

In summary, the panoramic camera is a special kind of camera for the security monitoring front end. It can realize a wide range of monitoring applications with the minimum cost, and it can well meet the needs of users for a wide range of wide-area monitoring. Its circuit integration technology is very high. If an engineering company uses a panoramic surveillance camera, it must understand the panoramic network camera in order to install it correctly and maximize its effectiveness.