新大地坐標數(shù)據(jù)管理系統(tǒng)的開發(fā)畢業(yè)論文外文翻譯(已修改)
2025-06-01 01:09 本頁面
【正文】 中文 3252 字 附錄 A:外 文文獻 Development of new geodetic coordinate datum management system Abstract： Current situations of geodetic coordinate datum development procedures and China were presented． The precisions of astronomic geodetic work and space geodetion Geodetic datum requirements under the current and future new surveying technologies and their applications were discussed． The necessity for upgrading national astronomic geodetic work and development of a new open coordinate geodetic datum management method was investigated． Key words： Geodetic Datum； Geodetic Network； Management INTRODUCTION Coordinates are the reference for surveying and mapping． The development for a high quality coordinate datum is one of the important tasks for surveyors over the world and also a reflection to the survey technologies in state． Currently， World Geodetic System 1984(WGS84)is the most popularly used coordinate system internationally． There are two nationally used coordinate system， in 1954 Beijing system and 1980 Xi’an systern． There are lots of local coordinate systems developed with different methods in some areas． Considering the importance of coordinate system， a high quality coordinate datum with modern management method is essential． GEODETIC COORDINATE SYSTEM STATUSIN CHINA At the beginning when founding our state． former Soviet Union Krasovsky’s ellipsoid was used for the development of reference coordinate system． The origin of this system was in former Soviet Union． The iointly surveyed coordinates of former Soviet Union geodetic coordinate work and the three points at Huma， Jilalin， and Dongning in Northeast of our country were taken as our astronomic starting reference data． Then a point in Beijing was calculated accordingly and was so called 1954 Beijing coordinate system． Since the founding of the state， a lot of surveying and mapping tasks were pleted with this coordinate system despite some problems existed due to the technological restrictions at that time． These prob1ems are： （ 1） The reference ellipsoid semimajor axis is more than 100m longer than modern precisely surveyed size． （ 2） The reference ellipsoid used is not identicall with the geoid of our counter． The elevation abnormity in Eastern is as high as 177。68 m． （ 3） The ellipsoid reference axis direction is not precisely defined． （ 4） Error accumulations are large and accuracy is low． To overe these problems and provide better services for economic development， national defence， and geodesy as well as space research， the Nation． al Surveying Bureau did adjust in one cast to national astronomic geodetic work in the end of 1970s and the beginning of 1980s． The 1980 Xi’an coordinate system was developed． IUGG75 ellipsoid was used in this system． The difference between ellipsoid and geoid is within 420 m and the side accuracy is 1/500 000 after adjustment． A new geodetic coordinate system is planning to meet the scientific needs in our country as the developments of new technologies such as very long base interfere(VLBI)and global positioning Systems(GPS)． The classes A and B GPS work were pleted and put in use respective in 1996 and 1997． The space geodetic work developments entered a new phase with these progresses． It is not
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