Which ellipsoid is the benchmark of the national 2000 geodetic coordinate system?

Traditional geodesy uses astronomical geodesy and gravity data to calculate the geometric parameters of the earth ellipsoid. Since19th century, many ellipsoidal parameters of the earth have been obtained. More famous are:

1, Krasovsky ellipsoid, whose oblateness is specified as1/298.3;

2. 1975 international ellipsoid, and the specified oblateness is/kloc-0 1/298.257；;

WGS-84 ellipsoid, the specified oblateness is1/298;

4.2000 China geodetic coordinate system (CGCS2000), defined as 1/298+0438+0.

Extended data

The national geodetic coordinate system is the basis of surveying and mapping the national basic scale map. According to the Surveying and Mapping Law of People's Republic of China (PRC), China has established a unified geodetic coordinate system.

Since the founding of New China, China established the Beijing coordinate system of 1954 and the Xi 'an coordinate system of 1980 in 1950s and 1980s respectively, and made topographic maps of various scales, which played an important role in national economy, social development and scientific research. Limited by the technical conditions at that time, China's geodetic coordinate system was basically realized by traditional technical means.

54 coordinate system adopts Krasovsky ellipsoid. In the calculation and positioning process, the ellipsoid does not use the data of China, and the system is not suitable for China, so it cannot meet the needs of high-precision positioning and the development of earth science, space science and strategic weapons. In the 1970s, after more than 20 years of hard work, Chinese geodetic workers finally completed the layout of the national first-class and second-class astronomical geodetic network.

After overall adjustment, Xi 'an coordinate system 1980 was established in China by using the reference ellipsoid parameter 1975 recommended by the 16th IUGG Congress. Xi 'an coordinate system 1980 has played a great role in China's economic construction, national defense construction and scientific research.

With the progress of society, national economic construction, national defense construction, social development and scientific research put forward new requirements for the national geodetic coordinate system, and it is urgent to adopt the coordinate system with the center of mass of the earth as the origin (hereinafter referred to as geocentric coordinate system) as the national geodetic coordinate system. Using geocentric coordinate system is beneficial to maintain and update the coordinate system quickly by using modern aerospace technology, determine the high-precision three-dimensional coordinates of geodetic control points and improve the mapping efficiency.

In March 2008, the Ministry of Land and Resources formally submitted the Request for Instructions on China's Adoption of the 2000 National Geodetic Coordinate System to the State Council, which was approved by the State Council in April 2008. From July 1 2008, China will fully launch the 2000 National Geodetic Coordinate System, which will be authorized by the State Bureau of Surveying and Mapping to organize its implementation.

Baidu Encyclopedia -2000 National Geodetic Coordinate System

Baidu encyclopedia-ellipsoid oblateness