Why is the model of sales center called "sand table"

sand plate

In military film and television works, we often see commanders standing in front of a terrain model to study operational plans. The model is made of sand, chess and other materials according to a certain proportion according to topographic maps, aerial photographs or field topography. Sand table is divided into simple sand table and permanent sand table. Simple sand table is made temporarily on the construction site with sand and chess; Permanent sand table is made of foam plastic board (or plywood), gypsum powder, paper pulp and other materials, which can be preserved for a long time. Sand table has the characteristics of strong three-dimensional sense, intuitive image, simple production, economy and practicality. Sand table has a wide range of uses, which can vividly show the terrain of the combat area and show the enemy's position composition, troop deployment and weapon configuration. Military commanders often study the terrain, enemy situation, battle plan, organize coordinated actions, conduct tactical drills, study war cases, and sum up operational experience. Sand table is also often used to make models of economic development planning and large-scale engineering construction, which is intuitive and favored by planners and engineers.