A map is a graphic that uses symbols, colors, text notes, etc., to depict the natural geography, administrative region, and socio-economic status of the earth's surface at a certain scale. Pen? Interesting? Pavilion wWw. ｂiquge。 ｉｎfo

In ancient times, it was a map that depicted the geographical situation of the land, mountains, and rivers, and later it was called a map that illustrated the distribution of things and phenomena on the surface of the earth.

Fang Xu studied geography in high school in later generations.

The three elements of the map: scale, legend, and pointer.

Scale bar: Indicates the degree to which the distance on the map and the distance from the field are reduced.

Legend: The language of the map, including the various symbols and their textual descriptions, geographical names and numbers.

Point marker to indicate the direction on the map.

According to the principle of going up, north, down, south, left, west, and right, Fang Xu in later generations has done many such geographical assignments.

As for military maps, it is a general term for maps that serve military strategy, tactical deployment, and marching combat.

Chinese military maps were highly valued in ancient times and were greatly developed. In 1972, the silk map unearthed in Mawangdui has a map of the garrison of the southern Xinjiang army in Changsha more than 2,000 years ago, which is the oldest clear and accurate military map preserved so far, and occupies a glorious page in the history of world maps.

The characteristics of military maps are that according to the requirements of the troops, the terrain, environment, and communication conditions should be very detailed. For example, the army uses a topographic platform, the scale can reach 1:50,000 to l:100,000, and the spacing of the contour lines on the map can reach 5 meters. The representation methods of military maps involve individual symbols, line symbols and polygon symbols, and there are standard standards for topographic maps in terms of color.

Fang Xu learned how to draw three-dimensional graphics in high school mathematics in his later life, and according to the information provided by the Tang Dynasty spies who infiltrated the ******, it was not too easy for Fang Xu to draw a simple military map.

Military maps have existed since ancient times, and they may not be as advanced as the three-dimensional drawing methods discovered, but this is not shocking to Li Shimin.

What Fang Xu really planned to take out was the sand table.

Therefore, Fang Xu drew the map for use on the march and for making a sand table for reference.

Sand table - a model made of sediment, war games and other materials according to topographic maps, aerial photographs or on-site topography in a certain scale relationship.

It is said that when Qin was deploying to destroy the Six Kingdoms, Qin Shi Huang personally studied the geographical situation of each country, and with the assistance of Li Si, sent the general Wang Jian to carry out a unified war. Later, when Qin Shi Huang was building the mausoleum, he built a large topographic model in his own mausoleum. In addition to mountains, hills, and castles, the model also uses mercury to simulate rivers and seas, and uses mechanical devices to circulate mercury.

Fan Ye of the Southern Dynasty Song wrote "The Book of the Later Han Dynasty? Ma Yuan Biography has been recorded: in the eighth year of Han Jianwu (32 AD), when Emperor Guangwu conquered Tianshui and Wudu, the general Ma Yuan "gathered rice for the valley and pointed to the situation", so that Emperor Guangwu suddenly had the feeling of "captive in my eyes", which was the earliest sand table operation.

However, the sand table never really came out.

In 1811, King Frederick of Prussia? Willem III's civilian military adviser von ? Leswitz, who made an elaborate model of the battlefield out of clay, used colors to represent roads, rivers, villages and woods, and small porcelain blocks to represent armies and weapons, which were displayed in the Potsdam Palace and used for military games. Later, Leswitz's son used sand tables and maps to represent the terrain and landforms, and used a chronograph to represent the deployment of troops and weapons, and planned strategically according to actual combat methods. This kind of "war game" is the modern sand table operation.

In the late 19th and early 20s, the sand table was mainly used for military training, and it was only after the First World War that it was widely used in practice.

In later generations of military-themed film and television dramas, commanders were often seen standing in front of a terrain model to study the combat plan. This kind of model, which is based on topographic maps, aerial photographs or on-the-ground topography, in a certain proportional relationship, is made of sediment, wargames and other materials

The sand table has the characteristics of strong three-dimensional sense, intuitive image, easy production, economy and practicality.

It is mainly used by commanders to study the terrain and combat plans, as well as to exercise tactics.