Transfer: http://www.rivermap.cn/docs/show-1829.html
Common Coordinate System Detailed
(A) the WGS84 coordinate system
WGS-84 coordinate system (World Geodetic System a 1984 Coordinate System)
Implementation uses the international geocentric coordinate system. Geocenter coordinate origin is, Z-axis spatial geocentric Cartesian coordinate system which is directed BIH (international time service) 1984.O protocol defined earth electrode (CTP) direction, X-axis zero point BIH 1984.0 CTP equator and the meridian plane intersection, Y and Z axes, X-axis perpendicular to the right-handed configuration, called the World geodetic system 1984.
(B) WGS84 Web Mercator
Web Mercator in 2005, Google first used in Google Maps, then or earlier Mercator Web users still call it the world Mercator World Mercator - Spherical Mercator (unofficial deprecated ESRI), code-named WKID 54004 ( in EPSG: 54004 or ESRI: 54004 in unofficial).
In 2006, OSGeo use code OSGEO in the proposed Tile Map Service (TMS) standard: 41001, WGS84 / Simple Mercator - Spherical Mercator (unofficial deprecated OSGEO / Tile Map Service).
August 6, 2007 Christopher Schmidt (one of the major contributors of OpenLayers) through a GIS discussion in order to use Google OpenLayers projection, the projection presented to Google (Web Mercator) using a uniform code (such as the existing 54004 , like code 41001) 900913 (also the shape of Google), and the same year on September 11 officially use the code 900913 in OpenLayers OpenLayers / Layer / SphericalMercator.js in.
In May 2008 EPSG in the 6.15 version of the official (probably Google Maps with great success) to Google map projection gives CRS Code EPSG: 3785 (Popular Visualisation CRS / Mercator), which is the Web Mercator officially EPSG organization admitted (Since the map is not a standard Web Mercator projection, EPSG has not been previously not included).
Soon EPSG use in February 2009 No. 9 New Code EPSG: instead of the previous 3857 EPSG: 3785, to the Google map projection method called "pseudo-public visualization Mercator" (PVPM), projection operator method code 1024.
So far, EPSG: 3857 (WGS 84 / Pseudo-Mercator) Code is the official web code Mercator.
In the GIS industry, is inseparable from ESRI, Web Mercator's code in ESRI also has a few. First to the Web Mercator projection of the name of the software ESRI 102113 (WGS 1984 Web Mercator), and EPSG: corresponding to 3785; later using 102100 (WGS 1984 Web Mercator Auxiliary Sphere), and EPSG: 3857 corresponds.
In ArcGIS version 10.0, ESRI official use EPSG: 3857 before replacing EPSG: 102100.
In short, Web Mercator is now officially official Code EPSG: 3857, 3785, etc., and at the same time 900913,3587,54004,41001,102113,102100 also refers to Web Mercator, although their specific definition there will be some differences, but they mathematically equal.
Web Mercator was a great success, and now the mainstream of Web Mercator map almost all use of the Web, such as foreign Google Maps, OpenStreetMap, Bing Map, ArcGIS and Heremaps such as domestic Baidu map, high moral map, Tencent GB 02 coordinates map and world map, etc. are also Web-based Mercator (due to domestic policy, there will be domestic map encryption requirements, there are two cases, one is through encryption on the basis of national standards on the Web Mercator Department cooked called "Mars coordinate system"; the other is further encrypted under 02 national standard coordinate system, such as Baidu map BD09 coordinate system).
(C) WGS84 UTM
UTM projection called "Universal Transverse Mercator", the English name for the Universal Transverse Mercator, the coordinate system is proposed by the US military in the 1947's. While we still see it as the "Gauss - Kruger," similar to the coordinate systems, but in fact UTM uses a grid of zoning (or block). In addition to using Clarke 1866 ellipsoid in the United States outside, UTM in other parts of the world have adopted WGS84.
UTM was developed by the United States, and therefore does not start zoning in prime meridian, but at 180 degrees, so all are within the United States with 0-30. UTM projection 6 degrees using zoning, starting from longitude 180 degrees (or 180 degrees west longitude), counting from west to east, and therefore with a central meridian of -177 (-180-- (- 6)), and 0 degrees longitude 30 and 31 as a boundary with the band, two band boundary 3 and 3 degrees, respectively. 8 degrees latitude using zoning, from 80S to 84N latitude band of 20 (X 4 with multiple degrees), respectively, with the letter C to X to represent. To avoid confusion and digital, I, and O not used. UTM is "false easting" is 500 kilometers, and "false northing" UTM Southern band is 10,000 km.
UTM is an isometric cut cylindrical projection and the horizontal axis, the cylindrical cut in the earth latitude 80 degrees north latitude and 84 degrees two contour rings, in many countries is used as the mathematical basis of a topographic map, such as China employed Gauss - Kruger projection UTM projection is a variation of a lot of remote sensing data, such as Landsat and Aster data application UTM projection released.
The UTM projection earth's surface between the latitudes of 84 degrees south latitude and longitude of 80 degrees by 6 degrees north and south divided into vertical strips (projection strip). East longitude 180 degrees starting from a projection of these numbered from 1 to 60 ed (Beijing in the first 50 bands). Each latitude band subdivided into quadrilateral difference 8 degrees. Two standard parallels from the central meridian is about 180KM, central meridian scale factor of 0.9996, UTM projection northern North pseudo zero offset, the southern hemisphere was 10,000 km.
(Iv) GCJ02 Projection Coordinates
GCJ-02 by the China State Bureau of Surveying and Mapping (G represents Guojia country, C represents Cehui mapping, J represents Ju Bureau) developed GIS coordinate system.
It is actually the real coordinate system artificially plus partial treatment, according to a special algorithm, encrypted real coordinates into a false coordinates, and this increase is not linear partial plus side, it will be offset over the situation is different . The coordinates of encryption is also often commonly known as "Mars coordinate system."
Coordinate of the coordinate system is latitude and longitude format, in degrees.
Here GCJ02 projection latitude and longitude, i.e. WGS84 latitude and longitude on the basis of the above, plus partial GCJ02 performed.
(E) GCJ02 Web Mercator
GCJ-02 by the China State Bureau of Surveying and Mapping (G represents Guojia country, C represents Cehui mapping, J represents Ju Bureau) developed GIS coordinate system.
It is actually the real coordinate system artificially plus partial treatment, according to a special algorithm, encrypted real coordinates into a false coordinates, and this increase is not linear partial plus side, it will be offset over the situation is different . The coordinates of encryption is also often commonly known as "Mars coordinate system."
Coordinate value of the coordinate system Mercator Web format, in meters.
Here GCJ02 Web Mercator, i.e. on the basis of a standard Web Mo Katuo above, plus partial GCJ02 performed.
(Vi) BD09 latitude and longitude projection
After BD09 belongs projected Baidu latitude and longitude coordinates, which is GCJ-02 plus bias latitude and longitude on the basis of standard, plus the added partial Baidu own algorithm, which is performed twice based on the standard biasing applied on latitude and longitude.
Coordinate of the coordinate system is latitude and longitude format, in degrees.
(Vii) BD09 Web Mercator shadow
After BD09 Web Mercator coordinates belong Baidu, GCJ-02 which is applied on the basis of a standard Web biasing Mercator on, plus the added partial Baidu algorithm itself, that is, on the basis of Mercator Web conducted two plus side.
Coordinate value of the coordinate system Mercator Web format, in meters.
(Viii) Beijing 54 coordinate system
中国成立以后，我国大地测量进入了全面发展时期，在全国范围内开展了正规的，全面的大地测量和测图工作，迫切需要建立一个参心大地坐标系。由于当时的"一边倒"政治趋向，故我国采用了前苏联的克拉索夫斯基椭球参数，并与前苏联1942年坐标系进行联测，通过计算建立了我国大地坐标系，定名为1954年北京坐标系。因此，1954年北京坐标系可以认为是前苏联1942年坐标系的延伸。T.A的原点不在北京而是在前苏联的普尔科沃。
自北京54坐标系统建立以来，在该坐标系内进行了许多地区的局部平差，其成果得到了广泛的应用。但是随着测绘新理论·新技术的不断发展，人们发现该坐标系存在很多缺点，为此，我国在1978年在西安召开了"全国天文大地网整体平差会议"，提出了建立属于我国自己的大地坐标系，即后来的1980西安坐标系。
（九）西安80坐标系
1978年4月在西安召开全国天文大地网平差会议，确定重新定位，建立我国新的坐标系。为此有了1980年国家大地坐标系。1980年国家大地坐标系采用地球椭球基本参数为1975年国际大地测量与地球物理联合会第十六届大会推荐的数据，即IAG 75地球椭球体。该坐标系的大地原点设在我国中部的陕西省泾阳县永乐镇，位于西安市西北方向约60公里。
中华人民共和国大地原点，由主体建筑·中心标志·仪器台·投影台4部分组成。
主体为7层塔楼式圆顶建筑，高25.8米，半球形玻璃钢屋顶，可自动开启，以便天文观测。中心标志是原点的核心部分，用玛瑙做成，半球顶部刻有"十"字线。T.A被镶嵌在稳定埋入地下的花岗岩标石外露部分的中央，永久稳固保留，"十"字中心就是测量起算中心，坐标为东经108度55分，北纬34度32分，海拔417.20米。仪器台建在中心标志上方，为空心圆柱形，高21.8米，顶部供安置测量仪器用。
（十）CGCS2000坐标系
2000中国大地坐标系(China Geodetic Coordinate System 2000，CGCS2000)，又称之为2000国家大地坐标系，是中国新一代大地坐标系，21世纪初已在中国正式实施。
20世纪50年代，为满足测绘工作的迫切需要，中国采用了1954年北京坐标系。1954年之后，随着天文大地网布设任务的完成，通过天文大地网整体平差，于20世纪80年代初中国又建立了1980西安坐标系。1954北京坐标系和1980西安坐标系在中国的经济建设和国防建设中发挥了巨大作用。
随着情况的变化和时间的推移，上述两个以经典测量技术为基础的局部大地坐标系，已经不能适应科学技术特别是空间技术发展，不能适应中国经济建设和国防建设需要。中国大地坐标系的更新换代，是经济建设、国防建设、社会发展和科技发展的客观需要。
以地球质量中心为原点的地心大地坐标系，是21世纪空间时代全球通用的基本大地坐标系。以空间技术为基础的地心大地坐标系，是中国新一代大地坐标系的适宜选择。地心大地坐标系可以满足大地测量、地球物理、天文、导航和航天应用以及经济、社会发展的广泛需求。历经多年，中国测绘、地震部门和科学院有关单位为建立中国新一代大地坐标系作了大量基础性工作，20世纪末先后建成全国 GPS一、二级网，国家GPS A、B级网，中国地壳运动观测网络和许多地壳形变网，为地心大地坐标系的实现奠定了较好的基础。中国大地坐标系更新换代的条件也已具备。
2000中国大地坐标系符合 ITRS(国际地球参考系统)的如下定义：
1)原点在包括海洋和大气的整个地球的质量中心；
2)长度单位为米(sI)。这一尺度同地心局部框架的TCG(地心坐标时)时间坐标一致；
3)定向在1984．0时与 BIH(国际时间局)的定向一致；
4)定向随时间的演变由整个地球的水平构造运动无净旋转条件保证。
以上定义对应一个直角坐标系，它的原点和轴定义如下：
1)原点 ：地球的质量中心；
2)Z轴：指向IERS参考极方向；
3) X轴：IERS参考子午面与通过原点且同z 轴正交的赤道面的交线；
4)Y轴：完成右手地心地固直角坐标系。
CGCS2000的参考椭球为一等位旋转椭球。等位椭球(或水准椭球)定义为其椭球面是一等位面的椭球。CGCS2000的参考椭球的几何中心与坐标系的原点重合，旋转轴与坐标系的Z轴一致。参考椭球既是几何应用的参考面，又是地球表面上及空间正常重力场的参考面。
等位旋转椭球由4个独立常数定义----CGCS2000参考椭球的定义常数是：
长半轴a=6378137.0m；
扁率f=1/298.257222101；
地球的地心引力常数 (包含大气层)GM = 3986004.418×E8m3s-2；
地球角速度w=7292115.0×E-11 rad S-1。
（十一）1985国家高程基准
我国于1956年规定以黄海(青岛)的多年平均海平面作为统一基面，叫"1956年黄海高程系统"，为中国第一个国家高程系统，从而结束了过去高程系统繁杂的局面。但由于计算这个基面所依据的青岛验潮站的资料系列（1950年～1956年）较短等原因，中国测绘主管部门决定重新计算黄海平均海面，以青岛验潮站1952年～1979年的潮汐观测资料为计算依据，叫"1985国家高程基准"。
我国的水准原点位于青岛观象山。T.A由1个原点5个附点构成水准原点网。在"1985国家高程基准"中水准原点的高程为72.2604米。这是根据青岛验潮站1985年以前的潮汐资料推求的平均海面为零点的起算高程，是国家高程控制的起算点。
由于国家水准原点实际高程并非为海拔0米，经国家测绘局批准，由专家精确移植水准原点信息数据，在青岛银海大世界内建起了"中华人民共和国水准零点"。
Level zero mark sculpture, 6 meters high and weighs 10 tons, the base like a plumb bob, meaning hard to measure older people working, there are six small ball on top of the globe, meaning the world's six well-known altitude origin. Below zero sculpture is an observation well, a lot of money has a value of huge red agate ball bottom observation wells, the top plane of the sphere is our country Altitude 0 meters place.