新大地坐標(biāo)數(shù)據(jù)管理系統(tǒng)的開發(fā)畢業(yè)論文外文翻譯-wenkub
2023-05-19 01:09:06 本頁面
【正文】 odetion 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。3 m． As a military targeted system， SA was carried out on the beginning of GPS system and was removed on May 2020 to meet its economic benefits． The US government provides higher accuracy of 177。1 m which means an accuracy of 177。1 m． The current national astronomic geodetic work accuracy is lower than177。 side transferring distortion was required 1ess than 1/40 000 due to technology considering． Thirdly， national defence considerations， transferring factors between 10cal coordinate systems and national datum are confidential ． The transferring tasks must be pleted through govern agencies． These kinds of 10cal systems are widely used． Fourthlv． for the reasons of local benefits， there exists several coordinate systems in the same area． They are independent of each other and of no conneetion． It is obvious that local system played important role in the history． With the advances of new technology， local systems blocked the new technology development and GIS can not share graphic applications． Thematicdata． GPS real time nayigation is an impossible mission． Integrated GIS and GPS receivers can not be used for data collection under local systems． The only choices for those new technology and equipment users are， first， not using them
畢業(yè)設(shè)計(jì)相關(guān)推薦
鄂ICP備17016276號-1