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-預(yù)覽頁
【正文】 period(2020 to 2020)； and the fourth phase is mercial operation perod(from 2020)． The characteristics of Galileo are its civil purpose and high accuracy． Free of chargeusers can reach177。． Elevation accuracy is better than 710． Absolute accuracy is better than m． For class B work， these accuracies are better than 410， 810， and 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 only with higher accuracy than former systems but also with three dimension coordinates which developed on internationaly defined ITRF frame． This high accuracy 3D space geodetic coordinate system will guarantee the infrastructure surveying for the first 10 years of twentyfirst eentury． After adjustment， the plate coordinate overlap accuracy of class A GPS work is better than 210。30 m from earlier 177。1 m global satellite positioning system will be available in 2020． The popularly used coordinate systems now in our country are 1954 Beijing system and 1980Xi’an system and 10cal systems are also based on these two systems． National coordinate system is actually national astronomic geodetic work． The national geodetic control point accuracy is far from the accuracy of 177。1 m． It is an urgent task to promote current national astronomic geodetic work accuracy． The national GPS class A and class B work has been developed． There are 27 points for class A work and more than 700 points for class B work． The point absolute accuracies of class A and class B work are177。近些年 ,我們就大地基準(zhǔn)的應(yīng)用 ,以及在當(dāng)代和未來的新測量技術(shù)的發(fā)展下開發(fā)大地基準(zhǔn)進(jìn)行了討論。目前 ,WGS84(世界大地坐標(biāo)系 )是在國際上使用最廣泛的坐標(biāo)系。 1 中國大地坐標(biāo)系統(tǒng)的概況 在建國初期 ,前蘇聯(lián)的克拉索夫斯基橢球被用來發(fā)展參考坐標(biāo)系。自從建國以來 ,通過這個坐標(biāo)系 ,我們完成了許多測繪工作 ,但是由于當(dāng)時技術(shù)的限制 ,也或多或少存在一些問題。 (3)參考橢球的軸向并沒有明確定義。這個坐標(biāo)系以 IUGG75橢球作為參考。伴隨著這些進(jìn)展 ,空間 大地網(wǎng)的發(fā)展進(jìn)入了一個嶄新的階段。高度精度優(yōu)于 710。 國家 A類和 B類大地測量控制網(wǎng)的建成說明我們已經(jīng)開發(fā)出了分米精度級別的絕對 3D大地測量控制網(wǎng)?？紤]到坐標(biāo)系對于國家經(jīng)濟(jì)發(fā)展和國防安全的重要性 ,坐標(biāo)系因子都是絕密數(shù)據(jù)。3 m。30m。第一階段時系統(tǒng)評價階段 (2020年完成 )。 Galileo的特點是它的民用性和高精度。1m的全球衛(wèi)星定位系統(tǒng)在 2020年將能夠投入使用。1m的精度還差很遠(yuǎn) ,所以 ,使用現(xiàn)代測繪技術(shù) ,省級我們的天文大地網(wǎng)是十分迫切的。政府機(jī)構(gòu)負(fù)責(zé)將坐標(biāo)系轉(zhuǎn)換為控制點。 GPS和 GIS的集成已經(jīng)成為一種趨勢。 現(xiàn)代地理信息產(chǎn)業(yè)的要求 作 為國經(jīng)濟(jì)發(fā)展的一個關(guān)鍵點 ,現(xiàn)在地理信息產(chǎn)業(yè)的影響越來越大。這些系統(tǒng)的發(fā)展和應(yīng)用給我們政府和經(jīng)濟(jì)管理也帶來了很大的改變。不同系統(tǒng)之間的轉(zhuǎn)換因子也是必不可少的。信息資源標(biāo)準(zhǔn)化是數(shù)字地球發(fā)展和運行的保障 ,不同坐標(biāo)系統(tǒng)之間的轉(zhuǎn)換因子是標(biāo)準(zhǔn)化的重要內(nèi)容 ,是數(shù)據(jù)共享的前提。當(dāng)代國家天文大地網(wǎng)的精度為 177。 A類網(wǎng)有 27個 ,B類網(wǎng)有超過 700個點。經(jīng)過數(shù)據(jù)處理 ,現(xiàn)在的國家天文大地網(wǎng)將得到升級。其次 ,出于技術(shù)考慮 ,側(cè)向轉(zhuǎn)換失真率被要求要小于 1/40000 。它們彼此互相獨立 ,沒有關(guān)聯(lián)。在地方系統(tǒng)中 ,GIS和 GPS集成接收器不能夠用作數(shù)據(jù)采集。地方坐標(biāo)系統(tǒng)是 技術(shù)上合理但管理值得探討的問題。
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