With the continuous development of the urban economy, the number of urban car ownership has increased rapidly, and traffic violations have become increasingly serious. Traffic violations are often the cause of traffic accidents and traffic congestion. They cause a certain impact on urban traffic operations while causing loss of people's property. The construction of the traffic violation automatic capture system can effectively provide real-time supervision for the traffic management department; with the relevant management, it can better regulate the road traffic operation. Different system designs have different construction, operation and maintenance costs and operational efficiency. Therefore, in the system design process, how to build a system with strong practicability, high reliability and intensiveness has become the focus of industry analysis and research.
Traffic violation capture requirements analysis
1.1 illegal capture of business processes
Through the external field capture camera, the collection of data such as vehicle data, pictures and short video streams is completed. At the same time, the data is transmitted to the central platform through wired or wireless mode; the platform sorts the data, centrally stores and filters, according to According to certain specifications, the illegal data will be exported. After the imported illegal vehicle data is confirmed, it will be transmitted to the illegal vehicle database of the public* internal network, and the penalty will be imposed.
1.2 illegal information to take * requirements
In the "Technical Specification for Image Obstacle of Road Traffic Safety Acts", according to the characteristics of road traffic safety violations, the picture mode is divided into 11 categories [1], and at the same time, according to different types of traffic violations Corresponding specifications and requirements for image acquisition equipment, timing error, number of pictures, picture quality, interval time and overlay information. For the illegal capture of red light, more detailed specifications and requirements [2].
Traffic violations capture the main technology
According to the relevant norm requirements, the traffic violation capture information is mainly the superimposed processed picture, short video stream and related data information. The capture of illegal information is mainly triggered by coil triggering and video triggering.
2.1 Traffic illegal capture processing technology
At present, the commonly used traffic capture processing technologies mainly include the following:
2.1.1 HD capture integrated camera
High-definition capture integrated camera built-in license plate recognition, vehicle identification and other functions, some use ARM embedded [3], DSP (Digital Signal Processing) technology. The integrated camera does not require a computer and an operating system to enable identification of the license plate and capture of the vehicle.
1) Fixed gun machine
The fixed type of gun is mainly for the capture of illegal activities such as the bayonet (handling the phone, not wearing a seat belt, etc.), not passing the prescribed lane, reverse driving, and not driving according to the guiding lane. Traditionally, the coil triggering method is adopted, and the signal is transmitted to the integrated camera for capturing and vehicle illegal information generation through the vehicle inspection device; with the development of the video processing technology, the application of the video triggering method is gradually popularized.
2) Ball machine
The integrated ball machine is often used for automatic capture of illegal parking. In this way, through the embedded intelligent module in the ball machine, the collection of illegal parking pictures, data, short video streams and the like in the capture area is completed, and the illegal information is transmitted to the central platform through the communication module (optical terminal or wireless communication module). In addition, the corresponding storage device can be set according to the requirements of the front office video and data storage.
The high-definition capture integrated camera capture mode adopts the embedded integrated design, which can be separated from the industrial computer to operate independently, can effectively reduce the number of external field devices, and has the advantages of small size, high integration, low energy consumption and high reliability.
However, this method is affected by the development of technology. In the early stage of construction, the equipment cost investment is relatively large; with the increase in the demand for the function of the traffic management department, the camera upgrade cost is relatively large.
2.1.2 HD camera + industrial computer
In this mode, the real-time video stream of the capture area is acquired by the camera and transmitted to the front-end industrial computer; through the front-end industrial computer, image processing and analysis technology is used to discriminate and intelligently analyze the traffic illegal vehicles in the video stream, and generate data according to the prescribed format. Illegal information data such as pictures, short pictures, or short video streams.
This method mainly relies on the industrial computer to intelligently analyze and process the video stream, and generate corresponding illegal vehicle data information.
This method has flexible adaptability to the demand of the different functions of the traffic control department through the upgrade of the industrial computer. However, in the early stage of the change, the industrial computer needs to be set up at the front end, and the number of external field devices is relatively large.
2.1.3 Camera + Center Analysis Server
The capture technology is mainly set for the traditional bayonet system. The traditional bayonet system embeds the recognition algorithm into the hardware device to identify the vehicle license plate, the license plate type, the vehicle body color and the like, that is, the first mode described herein. With the increase in the business needs of the public police department (such as the identification of new energy license plates, whether to drive mobile phones, or the use of seat belts to capture information), traditional bayonet embedded devices have been unable to meet the algorithms, and hardware devices are difficult to upgrade. . For large and medium-sized cities with perfect bayonet system, if the front-end camera is replaced by a large area, it will result in waste of assets. In order to achieve the business needs of the traffic control department under the existing traditional bayonet camera conditions, the capture technology solution of "camera + center analysis server analysis" has been developed.
The technology collects vehicle pictures and related data information in the monitoring area through the external field camera and transmits it to the central platform. The platform analyzes the server and performs secondary analysis on the collected images to complete the identification and generation of traffic violations.
This method is mainly applied to the traditional bayonet, and is used in the case of difficulty in upgrading the integrated capture camera. Can effectively avoid the waste of state resources.
2.2 Traffic illegal capture communication system
Traffic illegal capture data mainly involves illegal data, pictures and short video streams. Some regional management departments, some systems need to transmit real-time video stream information. According to the business needs and investment estimates of the traffic control department, wireless communication transmission or wired communication transmission can be selectively used.
2.2.1 Wireless communication transmission
The wireless communication transmission transmits the front-end capture data to the central platform by setting a wireless communication module at the front end. A common way is to rent a carrier SIM card and use the monthly traffic to transmit data to the central platform through the 4G network.
This method is mainly applicable to illegal activities such as picture, data and short video stream, such as bayonet, non-guided lane driving, reverse driving, illegal parking. This type of transmission mode requires less network bandwidth and a smaller amount of data transmission.
If there is a video streaming demand, the method can be used for temporary access of short-lived real-time video streams in terms of network bandwidth, traffic, economy, etc.; if external field video streaming is required, this method is not recommended.
2.2.2 Wired transmission
The wired communication transmission sets the front-end capture data to the central platform through the front-end setting optical module. A common way is to rent a carrier private network.
The method can meet the illegal capture of real-time monitoring of the video stream demand, that is, the real-time video stream is transmitted to the center while the traffic illegal capture is completed, and is used for public security* monitoring.
Storage requirements
In order to ensure the fairness and reliability of the data, the camera capture data requires front-end local storage and central storage for a specified time.
Under normal circumstances, the traffic control department illegally captures the system by storing information such as pictures, device data, and short video streams at the front end and center. Under this condition, the conventional capture camera front end is configured with a memory card to meet the storage requirements.
If the construction project includes public security requirements, real-time video stream storage is also required. Taking Shanghai as an example, in the construction of the public* digital high-definition image monitoring system, it is required to continuously record H.264 high-definition code streams of not less than 25 frames per second, and the storage time is not less than 30 days, and the standard-definition code stream does not require storage. "Each channel HD requires 2.92 TBytes of storage space. That is, an additional storage device is required.
system design
Under the same capture technology, the system architecture design is mainly based on the business requirements and storage requirements of the traffic management department. According to different needs, it is divided into two types: wireless transmission system design and wired transmission system. Taking illegal parking as an example, the system design is as follows:
4.1 Wireless transmission system design
The system mainly transmits illegal vehicle pictures, data and short video streams, and the illegal information is stored at the same time by the front end and the center.
In the wireless transmission mode, it can meet the demand that the business cannot capture the basic traffic illegally. It has the advantages of simple structure, low cost, short construction period (not involving cable laying).
4.2 Cable transmission system design
The traffic violation capture system adopting wired transmission can store and transmit video streams in real time on the basis of satisfying the basic illegal capture requirements, and has the function of monitoring and monitoring. Can meet the needs of multiple business units at the same time.
Compared with wireless transmission, the cost of the modification method is relatively high, especially involving the uncoated optical cable roads represented by the suburbs. In addition, if the front-end capture point is large, considering the factors such as network bandwidth and storage capacity, multiple sub-centers need to be designed for storage and transmission. The overall architecture is relatively complex.
in conclusion
This paper analyzes and studies the traffic violation capture system from the perspectives of capture processing technology, communication and storage. On the basis of the construction and management needs of the business department, combined with the existing project experience, considering the construction cost and practicability, the corresponding system architecture is proposed for different types of requirements, which provides a reference for the related project system design in the future. This paper mainly studies the system design from the demand level, involving the system software and platform part, and needs to design and research and develop according to the actual project requirements.
references:
[1] GA/T 832-2014. Road traffic safety violations image acquisition * technical specifications.
[2] GA/T 496-2014. General technical conditions for automatic red light recording system.
[3] Yu Qingjun, Hu Wei, Liu Jianwei, et al. Design and Implementation of Traffic Violation Capture System Based on ARM and Digital Camera[J]. Modern Electronic Technology, 2007, 30(6): 76-78.
Author brief introduction Wang Baili: Shanghai Intelligent Transportation Co., Ltd.
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