Map Knowledge-Coordinate Network

Geographic coordinate network)

For the convenience of creating and using maps, the map projected by Gaussian-lüge has two coordinate networks: geographic coordinate network and Cartesian coordinate network.

On the-topographic map of China, the geographic line is shown only in the form of a map. the latitude and longitude values are noted at the four corners of the internal and external charts, there are black and white lines or indicators with short lines indicating the longitude and latitude differences of 1. When necessary, the corresponding points are connected to form a very dense render network. On the-topographic map, the render network is directly drawn, and sometimes there is an encrypted splitting line for the encrypt render network. A latitude annotation is located between the East and the West, while a longitude annotation is located between the North and the South.

Cartesian coordinate network (fanwe)

The Cartesian coordinate net uses the central longitude line of each projection band as the vertical axis (X axis) and the Equator as the horizontal axis (Y axis ). The ordinate coordinates are calculated from zero in the equator. The north of the equator is positive, and the south is negative. China is located in the northern hemisphere, and the ordinate values are positive. The X-axis is supposed to start with a central longitude line of 0, and the East is positive and the south is negative. However, because the x-axis value is positive and negative, it is not easy to use. Therefore, it is stipulated that the X-axis value is increased by 500 kilometers, that is, it is equal to moving the ordinate axis to the West by 500 kilometers. The X-axis is calculated from the vertical axis, and the result is a positive value. Then, a number of straight lines parallel to the vertical and horizontal axes are made based on the equal distance of the kilometer, which forms the Cartesian coordinate network of the plane on the drawing, also known as the square internal network.