(2) The modern earth ellipsoid should have four parameters, both geometric and physical. Krasovsky ellipsoid has only two geometric parameters, which can not meet the needs of modern geodesy.
(3) The ellipsoid determined by ellipsoid positioning is not quite consistent with the quasi-geoid in China, and there is an obvious systematic tilt from west to east, with the maximum value exceeding 60 meters.
(4) The direction of the short semi-axis of the ellipsoid is unclear, which is extremely inconsistent with the present cosmic earth.
(5) The coordinate accuracy is poor.
Extended data:
I. Historical background
After the founding of New China, China's geodesy has entered a period of all-round development, and regular and comprehensive geodesy and mapping work has been carried out throughout the country, so it is urgent to establish a reference geodetic coordinate system.
Due to the political trend of "one-sided" at that time, China adopted the parameters of Krasovsky ellipsoid of the former Soviet Union, and made a joint measurement with the former Soviet Union 1942 coordinate system. Through calculation, the geodetic coordinate system of China was established, named Beijing Coordinate System 1954. Therefore, Beijing coordinate system 1954 can be regarded as an extension of former Soviet coordinate system 1942. Its origin is not in Beijing, but in Pulkovo, the former Soviet Union.
It connects the first-class shiplock in China with the first-class shiplock in the Far East of the former Soviet Union, and then uses the coordinates of the former Soviet Union 1942 Pulkovo coordinate system at the extension end of Huma, Jilanin and Dongning baseline networks as the initial data to adjust the first-class shiplocks in the northeast and east of China, so that the calculated coordinate system is named 1954 Beijing coordinate system.
Second, the difference between Xi 80 coordinate system and Beijing 54 coordinate system.
Xi 80 coordinate system and Beijing 54 coordinate system are actually an ellipsoid parameter transformation. For such transformations, the transformations within the same ellipsoid are rigorous, but the transformations between different ellipsoids are not rigorous, so there is no universal set of transformation parameters, and every place will be different, because they are two different ellipsoid benchmarks.
Jing 54 and An 80 are two different datum planes and different reference ellipsoids, so the coordinates of the same point under the two maps are different, no matter the coordinates of the third and sixth zones or the latitude and longitude coordinates are different.
Baidu Encyclopedia-Beijing 54 Coordinate System
Baidu Encyclopedia-1954 Beijing Coordinate System