With the development of cartography practice, human beings have learned to creatively express the real world by using various layers. Cartography has also accumulated many methods to describe elements, which are used to classify elements and identify signs, the shape of the earth's surface or the flow of resources and commodities.
Many ancient map expressions are still used in modern maps, such as double lines for roads, text for comments and blue for water bodies.
With the popularization of computers and the development of geographic information system (GIS) technology, maps have become very familiar printed matter, and maps can also be displayed interactively on computers.
Geographic information system further strengthens the interaction between people and maps. In GIS, you can easily determine the expression of information on the map, and you can also easily choose the location or target through query and analysis.
The function of map
Maps have the unique function of expressing the real world in many ways.
A map can identify what is in a certain location. On the map, pointing to any position on the map, you can know the name of this place or object and other related attribute information.
A map can indicate your position. If your map can input GPS data in real time, you can see where you are, how fast you are driving and where your journey destination is.
Maps allow you to identify spatial distributions, relationships and trends that cannot be reflected in other ways. Demographers can support public decision-making by comparing the city maps compiled in the past with the current city maps. Epidemiologists can find out the possible causes by linking the outbreak sites of rare diseases with the surrounding environmental factors.
Maps can integrate data from different sources into the same geographic reference coordinate system. The municipal government can adjust the municipal building structure in combination with the street distribution map and the building layout map; Agricultural scientists can combine meteorological satellite images with farm and crop distribution maps to increase crop yield.
Maps can analyze spatial problems by merging or overlaying data. The provincial government can find a suitable garbage disposal site by merging multi-layer data.
Maps can be used to determine the best path between two places. Through the map, the parcel delivery company can find the most effective transportation route; Public transport designers can also design the best bus routes.
Maps can be used to simulate the future. Public service companies can simulate the effect of adding new facilities and judge whether investment is needed according to this effect. Municipal planners can also simulate some serious accidents, such as the leakage of toxic substances, so as to get corresponding solutions.
The development of GIS technology has broadened people's understanding of maps. Compared with the past as a purely static entity, the current map has become the main means of dynamic expression of geographic information.
A map is a graphical representation of geographic information. In order to express information better, maps must be visually appealing. In addition, many experiences of graphic design, such as layout design, scale, color balance, symbols and layout, have been applied to map making.
Map can be understood as the medium between "geographic information" and "human understanding of information". Maps provide visual information about geographical objects and places by using human's unique and recognizable spatial pattern perception ability.
A map is an abstraction of geographic information. Different map users will have different understandings of map information. Maps will display specific information for specific purposes. Maps simplify some complicated and hidden data in the internal structure. At the same time, you can also describe the data on the map-for example, use labels to represent information such as name, category and type.
The purpose of data modeling is to design a data structure that can create maps with rich information and aesthetic characteristics. Understanding the expression of map information is the premise of creating an "appropriate" data model.
Electronic map and its function in intelligent transportation
Electronic map is a kind of geographic information system, which has most functions of geographic information system. Most of ITS information needs to be represented by electronic maps. Electronic maps can transfer digital signals (including digital maps, remote control)
Digital signals formed by visual processing of digital images and data collected from digitization) and analog signals are displayed on a computer screen.
Electronic map has two main functions: one is static display and dynamic display of multidimensional map; The second is the communication between spatial database and thematic database in dynamic environment. These two aspects interact to complete the visualization task of spatial data in GIS. As a visual product of spatial information, especially traffic information, electronic map in ITS conveys traffic routes and surrounding environment to users visually or even audibly, and becomes the most important tool for ITS to communicate with users. Therefore, the quality of electronic map production directly affects the success or failure of intelligent transportation system.
What is the important role of topographic map in military affairs?
The army is always inseparable from the map when fighting. Some comrades compare maps to "one language in cooperation", "silent guide to March", "eyes of the army" and so on. These metaphors vividly and appropriately show the important role of maps in military operations.
The role of maps in military affairs has been valued by military commanders from the beginning, with not only theoretical comments but also typical examples.
The ancient book "Guanzi" said that when planning combat operations, we should first analyze and study the terrain on the map, find out where the terrain is dangerous, where there are rivers that are not convenient for vehicles to pass, where there are commanding heights, where there are valleys, plains, hills and villages, and then decide on combat operations; Only in this way can we master the initiative, properly handle all kinds of situations and correctly use the favorable conditions of the terrain. That's what maps do.
During the Three Kingdoms period, after Liu Bei borrowed money from Jingzhou, he had the intention of "taking Xichuan (now Sichuan) as the base, then going north to Hanzhong, concentrating on the original and rectifying China". However, he is also worried about rugged roads, dangerous mountains and rivers, and unfamiliar terrain. Although he wanted to make progress in surprisingly, he never dared to make progress. At this time, it was reported that Yizhou (now Chengdu) did not drive (official name) Zhang Song, but brought a map of Xichuan to Cao Cao. Cao Cao didn't know that Zhang Song had come to present the map, so he looked down on Zhang and was teased by Cao Cao, so the map was not presented. After Liu Bei heard the news, he tried his best to win over Zhang Song. Zhang Song was very moved by the above guests, so he dedicated the map to Liu Bei.
This historical story tells us that maps have shown its important role in ancient times. So what is the role of maps in modern warfare?
In modern warfare, various services and arms cooperate to fight, the battlefield is vast, the suddenness and destructiveness of the war increase, the situation is complex and changeable, the organization and command are complex, and the dependence on maps is greater. Maps have become an indispensable tool for the military to organize and direct operations. Experience has proved that if a commander can use the map correctly, he can successfully complete the combat mission; If he can't use the map correctly, he may suffer setbacks in the war. For example, in a certain battle, a regiment was charged with infiltrating and encircling the enemy. Because the commander can use the map correctly, although the terrain is strange and complicated, he infiltrated 16 days and nights, with a journey of nearly 300 kilometers, and he was able to insert the designated position on time every time, successfully completing the combat mission. On the contrary, a battalion once performed the task of searching for enemy remnants, but the commander lacked the knowledge of reading and using maps and could not operate according to them. It was only three kilometers away, but it took nearly ten hours to get to the position, which led to the remnants of the enemy fleeing and delayed the fighters.
Compared with ancient maps, modern maps are quite different, with higher accuracy, more varieties and richer contents, and topographic maps are more widely used by various services and arms. For example:
Armored forces. It is an important assault force of the modern army, with strong assault and fast maneuverability. When carrying out tasks, it is mostly deployed in the far rear of the shade, moving forward quickly, rushing into the scheduled combat area, launching from the March, suddenly attacking and retreating quickly. Therefore, we should accept the task from the map, choose the route and deployment area on the map, study the terrain, enemy situation and operational deployment of the combat area on the map, and advance accurately according to the map.
Artillery. It is the main fire assault force of the modern army, and its basic task is to directly support and cover the operations of infantry and tank soldiers with fire. When the artillery carries out the emergency shooting task, it needs to organize the advance according to the map, mark the position with the map, and connect the battle formation with the map to obtain the shooting data.
Chemical soldier. It is the backbone of the army's anti-atomic chemical weapons, and its basic task is to organize and guide the army's anti-atomic chemical weapons and carry out atomic chemical observation and radiation reconnaissance. During reconnaissance, the polluted area should be marked on the map according to the map, and the reconnaissance report map should be drawn.
Engineer. When carrying out engineering support tasks, we should use maps to select roads, analyze road conditions, conduct road reconnaissance, select circuitous roads, plan and build emergency military roads, and draw up engineering support schemes.
Judging from the amount of maps used in modern wars, during the Second World War, the United States and Britain used more than 1000 kinds of maps in the North Africa campaign, with only two infantry divisions, 1 armored divisions, two infantry brigades, four reinforced regiments and eight battalions, with about107,000 people, and the number reached/kloc-. When the Anglo-American Coalition forces fought in Normandy, there were 3 group armies, 30 divisions, more than 5,000 naval vessels and12,800 planes, and about 2 million people used nearly 3,000 kinds of maps, reaching 70 million copies (about 1400 tons). When the US military invaded Korea, four divisions landed in the first month alone, using10 million maps, more than those used in World War I..
The above situation shows that topographic maps are playing an increasingly important role in modern wars and have been widely used.