Full resolution of Google maps map projection

Google Maps, Virtual earth and other network geographic use of map projection, often known as the web Mercator or spherical Mercator, its main difference with the conventional Mercator projection is to simulate the world as a sphere rather than ellipsoid.

What is Mercator projection?

Mercator (Mercator) projection, also known as "isometric positive-axis cylindrical projection", the Dutch map biologist Mercator (Mercator) in 1569, the assumption that the earth is surrounded by a hollow cylinder, its equator and cylinder contact, and then imagine the Earth Center has a lamp, Projecting the graph on the sphere onto the cylinder, and then expanding the cylinder, is a map of the world drawn by the "Mercator projection" of a standard parallel to zero (i.e., the equator). From the ball to the plane, there must be a conversion formula, which is no longer listed here.

Why did Google choose Mercator projection?

The "isometric" feature of the Mercator projection ensures that the object's shape is invariant, and that the square object does not become rectangular after projection. "Isometric" also guarantees the correctness of direction and location, so it is often used in navigation and aviation, and Google does not make mistakes in calculating the direction of people querying objects.

The "cylindrical" character of the Mercator projection ensures that the North and south (latitude) and the east (longitude) are parallel and perpendicular to each other. And the warp spacing is the same, the latitude interval from the standard latitude (here is the equator, may also be other parallels) to the two level gradually increased.

However, the "isometric" inevitably brings large deformations in the area, especially in the polar regions, notably as Greenland than the actual area of the enlarged N-fold. But if you go to the polar regions or reliable comrades, generally have more detailed information, will not come to see the network map, this does not matter.

(Photo source: Idvux blog)