How was the ancient land drawn?

In ancient times, when drawing maps, the planning method was adopted, that is, using map graphics to correctly reduce the size and design the scale. At first, the map was covered with squares, and the side length of each square represented the actual mileage. Moreover, the ancients would send people to various places to collect information according to certain standards. After collecting the data, they will draw the map content according to the grid. All previous dynasties have improved the accuracy of latitude and mileage measurement. Level was widely used in Song Dynasty, but in Jin Dynasty, six factors, such as scale orientation, road mileage, terrain height, angle and even curvature, were considered.