Coordinate concept examples and descriptions of Coordinate Systems

Geocoordinate

The coordinate of the reference elliptical sphere is used as the reference coordinate in the earth survey. The position of the ground point P is represented by the Land longitude L, the land latitude B, and the Earth height H. When the point is on the reference elliptical sphere, it is expressed only by the longitude and latitude of the Earth. The longitude of the earth is the angle between the Earth's radial plane and the starting Earth's radial plane. the latitude of the earth is the angle between the normal and the equator of the point. The height of the earth is the distance from the ground point along the normal to the reference elliptical sphere.

BEIJING 54 and Xi'an 80 are commonly used Coordinate Systems in China.

 

Which coordinate systems are commonly used for geographic data in China?

 

Coordinate System commonly used in geographic data in China

Differences between China's three common coordinate systems (Beijing 54, Xi'an 80 and WGS-84)
Gis application read 13 comments 0 font size: large, medium and small China three common coordinate system differences (Beijing 54, Xi'an 80 and WGS-84)
1. coordinate system of beijing 54 (BJZ54)
The coordinate system of beijing 54 is the reference coordinate system. A point on the earth can be located at the longitude L54, the latitude M54, and the geographic height H54. It is the coordinate system generated after local adjustment on the basis of the clasovski.
History of the 1954 Beijing coordinate system:
After the founding of the People's Republic of China, China's land survey entered a period of all-round development, and then carried out a formal and all-round land survey and ing work nationwide, it is urgent to establish a reference Earth coordinate system. Due to the "one-sided" political trend at that time, China adopted the crasovski elliptical parameter of the former Soviet Union, conducted joint tests with the coordinate system of the former Soviet Union in 1942, and established China's Earth coordinate system through computation, it is named the Beijing Coordinate System in 1954. Therefore, the 1954 Beijing coordinate system can be considered an extension of the 1942 coordinate system of the former Soviet Union. Its origin is not in Beijing, but in the former Soviet Union's polkovo.
BEIJING 54 coordinate system, which belongs to the Three-Axis coordinate system. The long axis is 6378245 m, the short axis is 6356863, and the flat rate is 1/298. 3;
2. Xi'an 80 COORDINATE SYSTEM
In April 1978, the National Astronomical geographic network adjustment meeting was held in Xi'an to confirm the positioning and establish a new coordinate system in China. For this reason, the national Earth Coordinate System was established in 1980. In 16th, the national Earth coordinate system adopted the basic parameters of the Earth elliptical system as the data recommended by the International Earth survey and geophysical Federation, that is, the IAG 75 Earth elliptical body. The Earth origin of the coordinate system is located in Yongle town, Jingyang County, central China, and about 60 kilometers in the northwest of Xi'an City. Therefore, it is called the Xi'an Coordinate System in 1980, also referred to as the Earth origin of Xi'an. The reference layer uses the average marine area of the Yellow Sea (that is, the 1985 National elevation reference) determined by the Qingdao Dagang tide verification station in ).
Xi'an 80 coordinate system, which belongs to the Three-Axis coordinate system, with a long axis of 6378140 m, a short axis of 6356755, and a flat rate of 1/298. 25722101
3. Coordinate System of WGS-84
World Geodetic System (WGS-84) is a kind of World coordinate System. The coordinate origin is the center of the earth, and the Z axis of the Cartesian coordinate system in the central Earth space points to the direction defined by the international time Bureau (BIH) 1984.0, the X axis points to the intersection of the BIH1984.0 protocol meridian and the CTP equator. the Y axis and the Z axis and the X axis form the right-hand coordinate system, which is called the World Earth Coordinate System in 1984. This is an international agreement Earth Reference System (ITRS), which is currently adopted internationally. GPS broadcast star calendar is based on the WGS-84 coordinate system.
WGS84 coordinate system, long axis 6378137.000 m, short axis 6356752.314, flat rate 1/298. 257223563.

Because of the difference in the elliptical benchmark used and the limitations of projection, the one-to-one conversion parameters do not exist throughout the country. Due to the large amount of data, if conditions are met, GPS is usually used for Joint Testing of known points, and the GPS software is used to automatically convert coordinates. Of course, if the conditions are not permitted and there are enough overlap points, you can also manually solve the problem.

Appendix:
Common elevation series in China
The "Yellow Sea elevation series in 1956" was determined in 1956. It is based on the Yellow Sea tide data of Qingdao tide test station from 1950 to 1956, and finds that the height of the horizontal copper wire in the tide test well of the station is 3.61 meters, so it is determined that the 3.61 meters below the steel wire is the Yellow Sea average sea surface. From this average sea surface, the elevation of the level origin in Qingdao was calculated as 1956 meters in 72.289.
The National 85 elevation reference is also the Yellow Sea elevation reference, but the old is called the Yellow Sea Elevation System in 1956, the new is called the "1985 National elevation reference", and the new is 0.029 m lower than the old one.
In 1956, china stipulated that the multi-year average sea level of the Yellow Sea (Qingdao) was used as the unified base area and the first national Elevation System in China. This ended the complicated situation of the elevation system in the past. However, the data series of the Qingdao tide site based on the calculation of this base surface (1950 ~ ) Due to a short period of time, China's surveying and mapping authorities decided to recalculate the average sea surface in the Yellow Sea ~ Based on the calculation of the Tidal Observation Data in 1979, and the leveling origin of the People's Republic of China in Qingdao was tested using Precision Leveling. The relationship between the National elevation reference elevation in 1985 and the Yellow Sea elevation in 1956 was obtained as follows: the National elevation standard elevation in 1985 = the Yellow Sea elevation in 1956-0.029 m. In 1985, the National elevation reference was started in May 1987, and in 1956, the Yellow Sea elevation series were abolished at the same time.
Relationships between different elevation systems:
56 Yellow Sea elevation reference: + 0.000
85. elevation reference (latest Yellow Sea elevation): 56. elevation reference-0.029
Wuzhi Elevation System: 56 elevation reference + 1.688
Pearl River Elevation System: 56 elevation reference-0.586
Currently, the general elevation reference in China is: 85.

 

 

 

Since the founding of the People's Republic of China, China established the Beijing Coordinate System in 1980 and the Xi'an Coordinate System in, respectively, and tested and produced various scale topographic maps, it played an important role in national economic, social development and scientific research. Due to the current technical conditions, China's land coordinate system basically relies on traditional technical means. 54. The coordinate system uses the clarsowski elliptical body. In the process of calculation and positioning, this elliptical system does not use Chinese data, and the system does not meet well in China, it cannot meet the needs of high-precision positioning and development of Earth science, space science, and strategic weapons. In the 1970s s, after more than 20 years of hard work, Chinese surveyors finally completed the deployment of the first and second-class astronomical geographic network. After the overall adjustment, the reference elliptical parameters recommended by the 1975 IUGG 16th conference were adopted, and China established the 1980 Xi'an coordinate system, 1980 Xi'an coordinate system played a huge role in China's economic construction, national defense construction and scientific research.
The coordinate system is a coordinate system established with reference to the elliptical sphere as the reference. The location of a ground point is represented by the longitude, latitude, and height of the Earth. The establishment of the Earth coordinate system includes selecting an elliptical system, locating the elliptical system, and determining the Earth's start data. A shape, size, positioning, and orientation of the earth's elliptical is referred to as a reference elliptical. Once the reference sphere is determined, it indicates that the coordinate system of the Earth has been established.
The earth's elliptical coordinate system is a coordinate system built based on the Earth's elliptical surface and the Earth's starting radial surface. It is the basic coordinate system of land measurement. Its land longitude L, the earth latitude B, and the Earth height H are the three coordinate components of the coordinate system. It includes the Central Earth coordinate system and the central earth coordinate system.
In the relationship between the Earth coordinate system and the radial Cartesian coordinate system, a is the long half axis of the earth's elliptical system, e is the first eccentric heart rate of the earth's elliptical system, and B is the earth's latitude.
The relationship between the earth coordinate system and the space Cartesian coordinate system e is the second eccentric heart rate of the elliptic, B is the latitude of the Earth, L is the longitude of the earth, and a and B are the long and short half axes of the Earth elliptical.