/kloc-In the 6th century, a great cartographer Mercator appeared in Holland. He drew the first map (Palestine) as early as 1537, and then accepted the field mapping task in Flanders, taking the magnetic meridian discovered by Columbus as the standard meridian, which was the beginning of mapping. 1540, Luwan opened a map workshop and printed a map measured in proportion, which attracted widespread attention and made a globe.

1568, the famous nautical chart "World Plan" was made, which adopted the isometric projection designed by Mercator, and was called "Mercator Projection", which enabled navigators to sail along a straight line (that is, isometric route) and show the world completely on the map for the first time. 1630 was widely used and played an important role in world navigation, trade and exploration.

Imagine cutting or cutting a cylinder with the same direction as the earth axis on the earth, projecting the graticule onto the cylindrical surface according to the equiangular condition, and then expanding the cylindrical surface into a plane to obtain the plane graticule. After projection, the longitude is a set of vertical parallel straight lines with equal distance, and the latitude is a set of parallel straight lines perpendicular to the longitude. The interval between adjacent latitudes gradually increases from the equator to the poles.

At one point, the length ratio in any direction is equal, that is, there is no angular deformation, but the area deformation is significant and increases with the distance from the reference latitude. This kind of projection has the characteristic of representing the equiangular route as a straight line, so it is widely used to compile nautical charts and aviation charts.

Extended data

Introduction of Mercator's principle of drawing a map of the world: suppose that the earth is enclosed in a hollow cylinder, and its reference latitude is in contact with the tangent (equator) of the cylinder, then suppose that there is a lamp in the center of the earth, project the figure on the spherical surface onto the cylinder, and then expand the cylinder. This is a map drawn by Mercator Projection at the selected datum latitude.

Mercator projection has no angular deformation, and the length ratio of each point to all directions is equal. Its longitude and latitude lines are parallel straight lines and intersect at right angles, and the longitude lines are equally spaced, and the latitude lines gradually increase from the reference latitude to the poles. The length and area of the map projected by Mercator are obviously deformed, but there is no deformation at the reference latitude.

The deformation from the reference latitude to the pole increases gradually, but because it has the characteristics of equal expansion in all directions, the relationship between direction and mutual position remains correct. Keeping the direction and angle correct on the map is the advantage of Mercator projection. Mercator projection maps are often used as nautical charts and aeronautical charts. If you follow the straight line between two points on the Mercator projection.

If the direction remains the same, it can reach the destination all the time, so it is beneficial for the ship to locate and determine the course during the voyage, which brings great convenience to the navigator.

Refer to Baidu Encyclopedia-Mercator

Baidu Encyclopedia-Mercator Projection