At present, most provinces in China have built on-line monitoring systems for different types of pollution sources, including sewage chemical enterprises, thermal power plants, chemical parks and key sewage treatment plants. Generally, various sensing sensors and monitors are deployed near the pollution sources through different types of sensing networks, Upload the collected data to the provincial / municipal environmental protection monitoring center to realize the real-time online monitoring of the discharge of major pollutants.1ã Pollution sources and video surveillanceThe essence of intelligent environmental protection is the combination of Internet of things technology and environmental informatization, and pollution source monitoring is an important part of intelligent environmental protection. Pollution sources can be divided into natural pollution sources and man-made pollution sources. Natural pollution sources refer to places where nature discharges harmful substances or causes harmful effects to the environment, such as active volcanoes. Man made pollution source refers to the pollution source formed by human activities, and it is also the main object of environmental protection research and control.Among the man-made pollution sources, according to the main objects of pollution, they can be divided into air pollution sources, water pollution sources and soil pollution sources. Among them, air pollution sources and water pollution sources are the two most influential sources on human life, and they are also the main application of video surveillance in intelligent environmental protection.At present, most provinces in China have built on-line monitoring systems for different types of pollution sources, including sewage chemical enterprises, thermal power plants, chemical parks and key sewage treatment plants. Generally, various sensing sensors and monitors are deployed near the pollution sources through different types of sensing networks, Upload the collected data to the provincial / municipal environmental protection monitoring center to realize the real-time online monitoring of the discharge of major pollutants.Due to the limitations of its own characteristics, such as high bandwidth occupation and low direct correlation with data, video monitoring has always been in an auxiliary or security position in the traditional pollution source monitoring projects. After the implementation, it is only used as an auxiliary means for panoramic view of the site situation, and is constructed separately from the traditional pollution data collection. In the past, the problems such as low definition of analog camera and difficult laying of transmission line make the video monitoring system separate from the whole pollution source data monitoring system, and the effective utilization rate is not high. Later, with the development of video technology, the definition was greatly improved, and the bitstream compression rate was higher and higher. The application of 3G / 4G wireless video and picture transmission technology made video monitoring have a new entry point in the field of pollution source monitoring.2ã Conventional scheme of pollution source video monitoringThe current basic framework of video monitoring of pollution sources is shown in Figure 2. The provincial environmental protection department and county and municipal environmental protection bureaus establish a two-level networking platform, and the front-end sewage enterprises are the classic security configuration of video access control alarm.The front-end video monitoring system is responsible for all-weather video monitoring of important places such as the main pollutant discharge outlet of the plant and the sampling place of the monitoring station, so as to meet the requirements of the environmental protection department for real-time monitoring of plant pollutant discharge.Basic framework of pollution source video monitoring1. Sewage outlet and monitoring stationThe factory will discharge a large amount of wastewater and waste liquid in production activities, including industrial production materials, intermediate products, by-products and pollutants generated in the production process, which are an important cause of environmental pollution, especially water pollution. The state has extremely strict standards for the discharge of industrial wastewater, but in the implementation process, there will always be some illegal enterprises trying to evade supervision by secretly discharging, so the monitoring of enterprise wastewater discharge is particularly important. (see Figure 3)System architecture of sewage outlet and monitoring stationEnvironmental protection departments generally have sewage monitoring stations in enterprises, which are responsible for detecting the wastewater discharged by enterprises, obtaining the content indicators of various pollutants, and ensuring that the industrial wastewater discharged by enterprises meets the specified standards. However, only data information is obtained in this way, which lacks an intuitive way to observe and understand the situation of wastewater, and most monitoring stations adopt the unmanned operation mode of automatic sampling and detection. In order to avoid the occurrence of illegal discharge, a set of video monitoring system needs to be deployed as the improvement and supplement of the monitoring system.Ball machines are deployed near the blowdown pipe and sampling port to ensure real-time and comprehensive observation of the whole process from sewage discharge to sampling, so as to eliminate the possibility of fraud by enterprises. The use of high-definition camera enables managers to clearly observe the color and other information of sewage through the monitoring picture, rather than relying on the detected data.Sewage monitoring stations are mostly unattended. In order to prevent the detection instruments in the station from being artificially damaged and stolen, and prevent enterprise personnel from entering and tampering with data, access control system can be deployed at the gate, and infrared double identification and infrared cameras can be deployed indoors. The monitoring station only allows people with authority to enter, and records all personnel entering and leaving, and keeps videos for future query. When someone invades, the linkage camera will automatically take video.2. Flue gas emission monitoringMost of the factory waste gas is discharged through the chimney. Generally, high-definition cameras are deployed at the height of the plant to cooperate with the PTZ, cover the chimney within the plant, and cooperate with the CEMS system for all-round flue gas emission monitoring. When CEMS detects that the pollutants exceed the standard, the management personnel can adjust the camera to the preset position to monitor the target chimney and obtain the real-time HD image of the scene, which is helpful to understand the whole picture of the event.3ã Integration of video and business systemWith the continuous development of the national video security monitoring industry, different industries such as public security, finance and environmental protection also put forward different monitoring requirements for security manufacturers. While leading the trend of high-definition and intelligent video, traditional hardware security manufacturers have based on their own products, subdivided the industry market, paid more and more attention to the environmental protection industry, explored the needs of the environmental protection industry through projects, put forward solutions for the environmental protection industry, and developed targeted industry platform software, This provides a technical basis for the integration of video surveillance and environmental protection business system. This integration is mainly realized through the following steps:1. Environmental protection business data acquisitionEnvironmental protection business data acquisition is generally realized through software docking. The Platform SDK provided by environmental protection business software and video monitoring software platform are developed to obtain relevant environmental protection monitoring system data.2. Video OSD overlayAfter the video monitoring software platform obtains the data, it uses the OSD function of DVR, IPC and other video devices to overlay the data into the corresponding video picture, so that the data can be presented more intuitively. The data is directly superimposed into the code stream for storage, and it is still the matching presentation of video and data in the later video playback3. Plan linkageAlarm thresholds of different types and levels can be set according to the content of environmental protection data monitoring. When the data exceeds the threshold, the set plan will be linked, such as the associated video pops up on the large screen of the monitoring center, central video storage, displaying location information / management information on the electronic map, SMS notification to management personnel, etc.4ã Technical requirements for video surveillance in environmental protection industryVideo technologies and concepts such as HD, intelligence, integration and linkage have been proposed and gradually matured. Video monitoring plays an increasingly important role in pollution source monitoring. At the same time, "smart environmental protection" also puts forward higher requirements for video monitoring software and hardware technology. Technology and industry demand promote each other and jointly promote the development of smart environmental protection.The requirements of smart environmental protection for video monitoring products and technologies are mainly reflected in the following aspects:1. HD technology to see further720p, 1080p and other high-definition images have been widely used in transportation and other industries with high video quality requirements. Pollution source monitoring involves the monitoring of small objects such as gas, particles and suspended solids, and there is also a demand for high-definition images.In addition to the high-definition of high pixels, you can see the high-definition laser PTZ camera several kilometers or even more kilometers away, which also has more use needs in water and air pollution monitoring.2. More transparent "fog" technology"Fog" here refers to haze, that is, the mixture of small water droplets or ice crystals suspended in the air and small solid particles. Haze will produce strong scattering and occlusion of light, blur the image and lose details. At present, there are two main types of video surveillance fog penetration technology, namely electronic fog penetration and optical fog penetration.