What are the commonly used projection methods?

There is also an important and practical projection-Weber Mercator projection.

Map projection used in network geography such as Google Maps and Virtual Earth is usually called network Mercator or sphere.

Mercator, the main difference between it and conventional Mercator projection is that it simulates the earth as a sphere, not an ellipsoid.

Web mercator projection coordinate system definition:

Taking the globe and equator as the standard latitude, the prime meridian as the central meridian, and their intersection as the coordinate origin, the east and north are positive, and the west and south are negative.

X-axis: because the equatorial radius is 6378 137m and the equatorial circumference is 2*PI*r =.

207508.4792, so the value range of X axis: [-207508,2008].

Y axis: According to Mercator projection formula, the above figure also shows that when latitude φ approaches the pole, that is, 90, the value of y tends to infinity. It is those "lazy engineers" who limit the value range of Y axis to [-20008092, 2008992] and make a square.

As we all know, the advantage of lazy people is to cut static pictures in advance and improve access efficiency. So the range (meters) in the projection coordinate system is: the minimum value (-2008,

-207508. 1992) to the maximum (200892, 2092, 20992).

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