What is the central meridian in Yichang, Hubei?

Central meridian 1 1 1. Enshi 108. Yichang 1 1 1. Jingzhou and Jingmen like to use 1 12.5 and Wuhan 1 14. Huangmei 1 17. The calculation method of central meridian has just arrived in a place, and when preparing for measurement, we often encounter the problem of not knowing the local central meridian and not knowing how to calculate it.

It is said that this is a relatively simple formula calculation problem, but it involves some basic knowledge of measurement. Next, we will analyze and explain the general process and basic principle of measuring with engineering stars. First of all, before building a project, we should know what coordinate system we are using.

At present, the most commonly used coordinate systems in China are Jing 54, Xi 'an 80 and custom coordinate systems, and will gradually transition to CGCS2000 coordinate system in the future.

After determining the coordinate system, determine the projection used in the coordinate system. The projections used in these coordinate systems are all Gauss-Kruger projections, which are an "equiangular transverse cylindrical projection"-there is no angular deformation, the length and area deformation are very small, the central meridian is not deformed, and the deformation increases gradually from the central meridian to the edge of the projection belt.

Extended data:

Function and Significance of Central Meridian

1, check the local longitude

When we are new to a survey area, if others only provide the coordinate system but not the central meridian, we can judge in the following way. Set up the instrument, click the "TG" shortcut key in the upper right corner of the figure below in the notebook, or press "6" in the notebook, or click the "telescope" icon at the bottom of the screen to view the local latitude and longitude information.

2, citing national control points

Generally speaking, the national control points are based on the normal 3-degree zone and 6-degree zone. You can usually tell by the belt number of the coordinates. In general RTK measurement, the projection is carried out with 3 degrees, so the deformation is small. Judging the central meridian according to the aforementioned L=3n.

According to the empirical calculation, as shown above, the degree in longitude is divided by 3. If it is not divisible, subtract 1 to get 1 12, add 1 to get 1 14, and divide by 3 respectively. If it is separable, it means that this is the central meridian. Here 1 14 can be divided.