Maps projected by DPT de la Guerre or sylvanus can keep the same area, but the length and angle will be distorted. As shown in the figure below, the picture reference: tbn3.google/images? Q = TBN: vjlfstdampwmupload.wikimedia/* */Mons/thumb/4/49/bonnet-projection/120px-bonnet-projection The other is Albers equal-area cone projection, which projects the earth onto a cone. In order to keep the projected area unchanged, the length of longitude and latitude of the projection is changed proportionally, as shown in the following figure. In other words, the shape will be out of shape. Argentina, for example, has a wide tail. Image reference: mathworld. Wolfram/images/EPS-/Albersequalalarm projection _ 900 There are many area-preserving projection methods. [1] But none of them projected the earth on a rectangular piece of paper. Most of the maps bought in the market are not like this. Other projection methods should be used. Take the Mercator projection as an example. This projection method is to project a sphere onto a circumscribed cylinder, and then unfold the cylinder. On the map drawn by this projection method, the latitude and longitude lines intersect vertically at any position, so that the world map can be drawn on a rectangle. In this projection, the linear scale around any point in the map remains unchanged, so that the angle and shape of the projected continental outline can remain unchanged. Figure 1
Fig. 3 Although the surface area of a sphere is the same as the lateral area of a cylinder. [2] But Mercator projection will deform this area. The farther away from the equator, the larger the area will be. This is because although the distance between two points on the sphere is very close, it can become very far after transformation, especially at high latitudes. [3] Therefore, the scale of the map is not consistent in various regions, that is, the area occupied by countries on the map cannot be expressed by the number of squares on the map. The error of area increases with the increase of latitude. At latitude 60, the area is increased by four times, but the two poles cannot be drawn, because Mercator projection can show the correct orientation between any two points and show the great circle route as a straight line. Therefore, Mercator projection is suitable for drawing nautical charts, but not for drawing political and economic distribution maps. Figure 2 Picture reference: tbn3.google/images? Q = tbn: qdl _ 8ansi5t1amspiff.rit.edu/classes/ast701/astrom/Tissot _ Mercator Figure 2 Picture reference:163.21.1. Orthographic Figure 3: For example, Africa is fourteen times larger than Greenland, but the size of the two is almost the same on the map. Alaska seems to be bigger than Brazil, but in fact Brazil is five times bigger than Alaska. Because China is farther from the equator than India, it will be larger, so the scale on the old map will be larger than 3: 1 note 1 en. * */wiki/equal-area _ projection # equal-area2 You can refer to Post's Wonderful Mathematical Proof 3EN. * */wiki/mercator _ projection 2009-03-0619: 09:18 supplement: some places are not good. The final distortion of the map at high latitudes is to make the area of each grid the same. Consider a sphere. Between two identical meridians, the area of latitude 30-60 is smaller than that of latitude 0-30, but it becomes the same on the map. So the area of high latitude countries has become larger on the map.
Reference: staff.amu.edu.pl/~zbzw/glob/glob0; Yeah. * * */wiki/Equal-area _ projection # Equal-area
Myisland's answer is wonderful! ! ! !
Old practice
It was also extended at the end of the first time.
Try to extend its exposure time.
The answer is really bad, please be sure to extend the question time.
On this map of the world
If you draw the spherical surface of the earth as a plane.
This will expand or shrink the land area of each country (in other words
The scale of the map is not the same in every region) because if the earth becomes round paper, it should be hundreds of millions of times larger than the map!
On this map of the world
If you draw the spherical surface of the earth as a plane.
This will expand or shrink the land area of each country (in other words
The scale of the map is not the same in every region) because if the earth becomes round paper, it should be hundreds of millions of times larger than the map.
There are different ways to draw the world map. Different map projection and drawing methods will have different effects on the regional scale. I don't know which one you specified. (hmm. *** /wiki/Map_projection)