The method of "planning in planning" is a method of drawing grids in proportion designed to correctly reduce the size of map graphics.

1. First, fill the map with a square, and the side length of the square represents the miles in the field.

2. Send people everywhere to collect all kinds of data according to certain standards.

3. Collect data and draw the map content according to the box.

Extended data:

Pei Xiu of Jin Dynasty (AD 223-27 1) showed a set of map-making theories, and drew a map of Gong Yu area on this basis. His theory can be summarized as "six-body mapping", that is, six factors to be considered in mapping: scale (scale), sight (azimuth), road mileage (road mileage), height (terrain height) and height.

"Six-body Cartography" has become an important basis of China's traditional cartography theory, and the planning rule is the basic operation method. Both of them have been used for more than 1500 years, and the famous maps of past dynasties are indispensable for planning. Pei Xiu was followed by Jia Dan's Map of China and Foreign Countries in the Tang Dynasty, Shen Kuo's Map of World Counties in the Northern Song Dynasty and Zhu Siben's Map in the Yuan Dynasty.

The improvements made by dynasties mainly lie in the accuracy of latitude and mileage measurement and the conversion ratio. In the Song Dynasty, instruments such as "level", "sight scale" and "dry scale" were widely used to measure the height of the terrain. In Shen Kuo, "mutual similarity" is used instead of "tunnel", which may be a modern outline mark.

References:

Baidu Encyclopedia-Planning Scheme