The choice of camera and its role in road monitoring

In order to improve the traffic congestion situation, cities are gradually promoting the implementation of real-time traffic situation image monitoring system plans for major traffic crossings, ie installing an intelligent road monitoring system at each important traffic crossing in the city, and realizing road traffic conditions through image transmission channels. Uploaded to the road monitoring command center, the center staff on duty can understand the road conditions in each area in order to adjust the flow of vehicles at each intersection to ensure smooth traffic. To monitor the violation of road vehicles, they can find and arrange road traffic in a timely manner. Whether it is a red light or a reverse driving, as long as the motor vehicle violates the “People’s Republic of China Road Traffic Safety Law” when passing through the main intersection in the city, it will be recorded by the electronic police and camera monitoring equipment. The illegal vehicle information is in the public security traffic command and control center. Was printed in time. The use of high technology to manage traffic has increased work efficiency and has facilitated the driver.

Summarized the main role of urban road monitoring system has the following two points:

1. Real-time monitoring of road conditions: cameras at each intersection will timely transmit the real-time images of the monitored area to the traffic command center so that the traffic commanders can grasp the traffic conditions of each intersection and road section in real time. For example, whether the traffic flow and signal light of the road section are working properly. , whether there is illegal behavior and traffic accidents. This information can help the traffic management department to take appropriate measures in a timely manner.

2. Real-time recording: The image of the video surveillance will be saved to the video server of the traffic command center as evidence for the handling of traffic accidents, irregularities, and even crimes such as public security crimes.

The requirements and selection of road video surveillance cameras are all-weather surveillance. Therefore, the requirements for front-end cameras are relatively high. The cameras are required to clearly monitor the vehicle license plates, vehicle types, and colors on the roads.

If the video system in road monitoring is likened to the human visual system, then the video camera in the video system is like the eyes of human beings. Its importance is self-evident, so the choice of cameras in traffic surveillance is very demanding.

Traffic road surveillance camera selection must first consider the following two requirements:

1, performance: camera performance is directly related to the ability to take a clear picture under a variety of conditions, can see the license plate at night, the color of the picture taken is true;

2. Reliability: The camera should be able to work stably for a long time in various harsh environments to ensure that the image quality does not deteriorate and the failure rate is low. If the "eyes" of a traffic monitoring system are not good or go wrong, even if the rest of the system is perfect, the defects of the entire system are clear.

The most widely used traffic surveillance cameras are fixed-lens cameras. The selection and application of these cameras should focus on the following major technical parameters and functions:

1, camera resolution, image resolution is greater than 500 lines, and then configure the high-definition monitor, there will be a better monitoring effect. Cameras with a horizontal resolution greater than 500 lines have a sharper, sharper image than cameras with 480 lines. Therefore, the higher the resolution, the better the camera's performance.

2, camera sensitivity, the minimum illumination index can not just look at the number of the front, but should see under what conditions this indicator is measured. For example, the minimum illumination of color is 0.15 Lux/F1.4/50 IRE/AGCON, which indicates that the low illumination of 0.15 Lux is achieved with a F1.4 pass lens, and the video signal measurement level is measured at 50 IRE (350 mv) under AGCON conditions. If the F1.0 lens with a large amount of light is replaced, the video signal measurement level is at 25 IRE, and the measured low illumination index is even lower. The 1/2-inch CCD camera has better sensitivity and image quality than the 1/3-inch CCD camera.

3, the camera's signal to noise ratio. When the light is very good, the camera's signal-to-noise ratio is very good, the noise point can not be seen in the image, but when the light is dark, the camera image with good signal-to-noise ratio index is still clear and the noise point is small. In cameras with poor signal-to-noise ratio, noise points can overwhelm the entire image.

4, camera light suppression, road surveillance cameras require clear vehicle license plate at night, which requires better light suppression indicators. The camera with this technology can effectively suppress the strong light (vehicle headlights) of the oncoming vehicles, so that the license plate can be captured more clearly and the picture is true and complete. Many road surveillance cameras use "solar eclipse" technology, which is very good for shooting license plates at night, but it often occurs during the day, which affects the overall appearance and integrity of the image.

5, camera backlight compensation function, the camera shooting license plates at night, backlight compensation technology is good or bad, is directly related to whether you can clearly see the license plate, can make the rear-end video detection and analysis system gives correct judgment results. Good camera for the backlight compensation area can be flexibly set and area selection.

6, the camera's color reproduction performance, the camera does not have a specific color index, can only use the color adjustment and white balance adjustment to make the color true reduction. Different types of cameras have different color reproduction performances. This indicator only compares with debugging and actual color in the scene. You can select cameras with many white balance adjustment methods, such as white balance manual adjustment mode, white balance automatic tracking adjustment mode, indoor mode, and outdoor mode.

7. Digital noise reduction technology for cameras In the dark environment, the camera noise will inevitably increase due to the illumination problem, and the current unique digital noise reduction technology can be used. Make the images under low light conditions clearer and more pleasing.

Digital noise reduction technology is the use of professional video signal processing technology, DSP chip by detecting and analyzing the image information in the frame memory, automatically reduce the relative amplitude of the still picture, greatly eliminating the signal interference noise wave, which effectively improve Picture clarity and cleanliness.

8, the convenience of camera debugging, the camera in addition to reliable quality, but also easy to install and debug. Road surveillance cameras are mostly installed on posts that are 9-15 meters high. They require special tool carts for installation and removal. They are dangerous high-altitude operations. If the quality is unreliable or debugging is inconvenient, it will inevitably cause great costs for construction and engineering. And affect the normal use.

You can use the camera's RS-485 port to set up and debug the camera. Through this port, you can remotely control the camera, modify the parameters inside the camera, and do not need to go to the scene to adjust the camera; through this quick and convenient port, it greatly saves manpower and debugging time. At present, many cameras have this interface function.