TMC (Miscellaneous on information collection, system display, and navigation functions)

TMC (Traffic Message channel, traffic information channel) is what we often call real-time traffic conditions, if in a narrow sense, may be the RDS-TMC of Europe, A real-time traffic condition transmission and Receiving System Based on fmbroadcast. Its broad understanding has completely exceeded European standards. Data Transmission can not only use fmemission, it can also be transmitted through GPRS or dab, and TMC is not only traffic condition information, but also weather information, the final development and evolution may be able to transmit a lot of real-time information such as parking spaces, cinema seats, and dining at restaurants. It is like an LBS system. So what is the role of TMC at this stage? According to the provided information, it is to inform the driver of the degree of road congestion, sudden traffic incidents, traffic control and other traffic information, and the host of the traffic broadcasting station keeps broadcasting real-time traffic information similar, however, radio stations are just artificial speech. The most important function of TMC is not only to inform users of traffic information, but to provide navigation suggestions in GPS navigation devices to reasonably avoid traffic sections such as congestion control, so that users can reach their destination as quickly as possible. TMC is probably like this. Let's take a closer look at my understanding of TMC.

So far I still don't understandHow does TMC obtain traffic information?Yes, the traffic police department may be on duty, so it is easy to get traffic information. Of course, I think so many traffic probes are also an important way to help the traffic police obtain traffic information, however, traffic control information is the first thing they know. Therefore, the Traffic Police Department may obtain traffic information in many ways, but there are few electronic technologies, human judgment may be needed (this is probably the most effective method ). For TMC companies, of course, it is impossible to obtain information directly from the Traffic Police Department (of course, it may also be possible to obtain the transportation information of the transportation department through other channels), so it may be the same as the transportation department, the traffic information officer is used to set a person to collect real-time traffic information. The traffic broadcasting station uses drivers and friends from various places to send text messages or call the radio station to inform them of the traffic conditions, it is also a relatively effective method. It is said that the most common form of TMC is floating cars. The method may be like this, for example, cooperation with a taxi company, install a device on the vehicle to get the current speed and continuously return information to the company, and obtain the speed of each road section in real time (of course, the speed after multiple vehicle weights) vehicle speed is the most important criterion for road congestion. Of course, the disadvantages in this case are also very obvious. If the number of floating cars is not enough, or the distribution of floating cars is uneven, it will affect the data quality. I was wondering if a certain number of radar or infrared speed would also be able to achieve the purpose of Road Condition Monitoring in each road section. However, such work may only be done by the transportation department, ordinary people or companies may not be able to do this.

After the data collection is completed, the following is the processing, and the data processing is also a very critical part.AlgorithmIt will also affect the final data. After all, how to calculate the weights of so many pieces of data sent to the server is a scientific algorithm, but I do not understand this part, so there is no reason. In addition, network transmission is also worth considering. It is also critical to obtain data as quickly as possible and send it to the client as quickly as possible. If the network is slow and the solution is slow, the last data sent is the data sent more than half an hour ago. Is it real-time traffic conditions? accuracy is not to mention. A company's response interval to real-time traffic conditions is also a manifestation of its strength.

After the information is collected and computed, You need to publish the information, which is an electronic signal, which is invisible to users. Non-graphic non-voice signals have no significance for users, so how? In fact, there are many methods, such as the notification of the radio broadcaster, the 10086 voice consultation, and the road congestion information signs on the loop are all forms of expression, but they are relatively simple. The most important thing isReleased on the Web endOr how to implement real-time traffic information on the mobile phone end?

Before that, let's talk about the simple TMC performance. Generally, the linear representation is dominant, the red indicates congestion, the yellow indicates slowness, and the Green indicates smoothness. This is generally the case of traffic accidents, in addition to the color accident that affects the line, it is necessary to express it with the symbol of a traffic accident in this location, which is actually a point. After the presentation, we can talk about the implementation method:

1. The simplest way: instantly draw the color of the exit segment and mark the traffic accident point. The road information congestion indicator board on the expressway is the simplest way to draw. The fixed line type (the LCD lamp has fixed the shape according to the road shape) is fixed, and different colors are issued to indicate congestion information, it is still red, yellow, and green, the simplest way. However, if you do it based on the web, you can even use SVG or VML to plot it. Instead, you only need the drawing software with the graphics engine. Updating real-time traffic conditions is constantly refreshing the drawing of images. However, these are relatively basic forms, but they are also very effective.

2. webmap-based method (My Idea): draw a line or point over the existing webmap, but the basemap that comes with webmap is the basic data. You can use the mapbar engine or Google Maps API. I personally recommend GMAP API, because if you draw a lot of line and point on your browser, in addition to the high memory consumption, the engine also needs to have such capabilities. Compared with Google's optimization, it should be good, and the engine's affordability is also acceptable. And most importantly, gmap api supports kml. You even need to constantly update your kml data to show real-time traffic conditions, but I have never done such a test, not to mention the stress test on the webmap engine. However, this method is also relatively bad, because in the case of a large amount of data, the chance of a browser crash is relatively high (Personal ignorance ).

3. Overlay images on the webmap: The webmap serves as the basemap basic data, and the TMC data is used as a layer on the webmap. The image is superimposed instead of the baseline, does gmap api support overlay, so you only need to generate real-time traffic picture overlays. As for how to generate images, the method is simple, that is, WMS. It should be possible to use geoserver or ArcIMS. In fact, the first method above can also be implemented directly using WMS. We only need to update the background database or map files, and WMS constantly refresh and output New Road Condition images so that dynamic road conditions can be achieved. The method is also relatively simple. Most companies use this method to implement TMC. (If an error is returned, correct it. I personally think that the Wikipedia map superimposed on Google map should also use the overlay WMS image method, rather than the direct marker)

The above is my personal thoughts on TMC, which I can think. SoHow to act on NavigationThis is the most critical point. Let's talk about the principle. In fact, what I did not mention above is: what is marked with red lines, what are marked with green lines, how can we change the red color from a congestion to a smooth Green Line, and how can we do this? All real-time traffic conditions are actually related to the road. Even if every road is long or short, the whole road is not blocked by a traffic jam. In fact, it is very simple to interrupt all the roads, in principle, the more segments, the more delicate or practical they are, the more reasonable they are to interrupt at the intersection of the road and road. If necessary, further interruptions can be made, and each segment is a record, the speed information will be assigned to these roads. Even if the traffic jam or not is assigned to these roads, the drawing will know the coloring information. The plain text is simpler. All road sections (not roads) in a region are recorded in the database. One road section is a record, and each road section contains coordinate information, the coordinate information is used to plot the line shape, and the real-time road condition of each road section is only one of the three conditions, either smooth or congested or slow, according to these three situations, the line is colored with red, yellow, and green, and the real-time traffic information is clearly displayed. This is a summary of the above three ways of expression, but it is also very important for navigation.

in the navigation electronic map, all roads are displayed in the form of road sections. Each road section is a record, with the form, level, speed, name, and single line information, of course, there is a unique ID mark, otherwise the coloring mentioned above is also impossible. After understanding this, we can link up the entire implementation idea and understand how TMC and data companies and navigation software companies cooperate. First, TMC divides roads according to its own method to facilitate the distribution of road condition information to each road section. Then, it cooperates with the Data Company, the data company maps the road section ID provided by TMC to the road section ID in the navigation electronic map. TMC does not even need to consider coordinate information, because the data company's electronic map contains the coordinate information of road forms. The two ID tables are crucial tables. Once the corresponding error occurs, the entire TMC system is in disorder, and navigation cannot be used, because the map of the traffic jam on the East Road released by TMC corresponds to the traffic jam on the west road, that's even better. In terms of terms, the two tables provided by TMC are location tables, while the data companies provide matching tables, which are easy to understand, TMC company issues a location-based road condition information table, and data company makes a road section corresponding table. For navigation companies, how to use TMC information? In fact, for navigation, route planning should consider information such as road level, road speed, and single-line road restrictions, the tmc information is another reference information that affects route planning. Based on the traffic information provided by the TMC, the road section is assumed to be of a lower grade, a lower speed, or a restricted entrance, it can be said that TMC information dynamically changes the attributes of the road to affect the overall route planning. Of course, the addition of TMC information results in, route Planning also needs to constantly change the route over time to make the route more reasonable. It is impossible for the previous route from a starting point to the ending point to remain unchanged. For example, when a traffic accident occurs on a certain road section, the entire road section quickly changes from smooth traffic to slow traffic. If the accident is serious, it may even become congested, and TMC immediately captures the information and solves the problem successfully, through the network (either FM, GPRS, or DAB) broadcast transmission, there is already a receiving device on the GPS navigation device that receives the accident information, the originally planned route through the accident section needs to be re-calculated, bypassing the accident Section to continue to walk in a relatively smooth road section, so as not to enter the congestion status in the accident section. It can be seen that TMC information is very useful.

TMC Technology Outlook. Strictly speaking, TMC technology should be regarded as a branch of LBS technology, and TMC technology is most likely to evolve into LBS technology. why are so many companies engaged in TMC and invested a lot of money, I am personally worried about the current navigation electronic map industry, because at present, navigation electronic maps are burning money, and there are only a few profitable companies. Although more than a dozen companies have class A qualifications for navigation electronic maps, however, there are only a few items that really make navigation electronic map data. Some of them are because their maps can be equipped with their own software for a price, and some have never released navigation electronic maps. Does TMC need to develop like this? It is unknown that the situation may be the case. The best thing in the industry should be century Qualcomm. In addition, it may have a good prospect when it is acquired by sivertu, but it should not be profitable for the time being, I am puzzled because there are only a few TMC listings. As for the prospects, suchArticleAs mentioned at the beginning, the important thing is to first link up this channel, from data collection technology to the release of mature applications to the customer. It will be worth looking forward to in the future, because TMC itself is a value-added service, and value-added services can have a lot of content, next time it will not only be TMC, it may be weather forecast, parking space information, and so on. For downstream industries, it can be the navigation market, or the service market of 10086, or webmap, or even its research department. Like logistics in the early years, whoever has mastered the path controls the market (I can't remember the specific sentence, but the meaning is probably so ). Who has mastered the TMC channel technology, who has mastered the upstream and downstream markets, and does not know whether it is one-sided, but at least it has an impact on the upstream and downstream markets. Let's look forward to the rapid development of TMC.

I should have written at least two articles (one is a webmap-based TMC demonstration, and the other is how TMC acts on the navigation system). Finally, I became an article, therefore, it can only be said to be a mix of things. I have only been in touch with TMC and have no idea about TMC technology. I can only understand TMC correctly or not, also hope to make bricks.