The Establishment of Geodetic Datum in Jiaonan City

摘要

As to Jiaonan geodetic datum, third-order horizontal control network is established through GPS while third-order leveling network is established through electronic level. This paper illustrates how to process data so as to improve horizontal and vertical precision in the process of establishing third-order horizontal control network and elevation fitting. It puts forward such an opinion: making precision test for starting points of horizontal network and preserving those short baselines of low precision in unconstraint three-dimensional adjustment; As to elevation fitting, we advocates employing a variety of fitting scheme make precision inspection for those known GPS leveling points as well as those unknown points' fitting level. Then the most probable level is just what we get. Afterwards, we calculate those unknown points' root mean square error of fitting height, plus the minimum and maximum difference between fitting height and the most probable height. Taking all the results of precision inspection into consideration, we can find out the best fitting scheme, which improves the systematic precision and reliability of geodetic datum.