On the establishment of 3-dimensional national control points in Korea

With the development of GNSS (Global Navigation Satellite System) positioning technology, the traditional control point system, which is composed of 2D (horizontal) + 1D (vertical), is being changed to the 3-dimensional control point system in Korea. In this contribution, the concept of the 3-dimensional geodetic network on the basis of UCP (unified control point) and the strategy for the realization of the network is suggested. In addition, the expected precision of the new geodetic network especially focused on the vertical position is verified based on the result of the vertical adjustment in the area of the 12th leveling loop. In this area, the network is newly composed based on the strategies such as the transformation of the benchmark to UCP and replacement of the benchmark with UCP, and new establishment of UCPs. The result of the adjustment for the newly designed network shows that a posterior standard deviation of 1.5 mm and the precision of the vertical position better than 2.5 cm for 97.6% of the control points. This clearly verifies that the 3-dimensional network based on UCPs provides the 3-dimensional position with a precision better than 3 cm in most of the cases.