The ratio of the line segment length on the map to the corresponding field line segment length. It represents the reduction degree of map graphics, also known as scale reduction. For example, 1:65438+ million, that is, the length of 1 cm on the map is equivalent to 1000 m on the ground. Strictly speaking, only on a large-scale map representing a small area, because the curvature of the earth is not considered, the scale of the whole map is consistent. For general maps, the scale of deformation caused by projection is not exactly the same everywhere. The scale usually drawn on the map is called the main scale. Main scale is the reduction rate of the ellipsoid of the earth when the map is projected. On the map, only some lines or points conform to main scale, and the scale of other places is larger or smaller than that of main scale. The scale is related to the details and accuracy of the map content. Generally speaking, large-scale maps with detailed contents and high geometric accuracy can be used for mapping on maps. Small-scale maps are universal and not suitable for surveying and mapping.

Map scale: the ratio of the length of a straight line segment on the map to the horizontal projection length of the corresponding straight line on the ground.

According to the map projection deformation, the map scale is divided into:

Principal scale: The scale of a point or line without distortion on the projection plane.

Local scale: the scale with deformation on the projection plane. ① The digital scale is 1: 10 000.

(2) the proportion of words, such as one million.

③ Graphic scale

Linear ruler

Oblique scale, also called differential scale, is a graphic scale based on similar triangles principle. The measurement accuracy reaches three digits (10-3).

Compound scale

④ Special scale

Variable scale

Stepless scale