Of Gis Electronic Map Coordinate System Conversion

There are Beijing 54 Coordinate, Xi'an 80 Coordinate and WGS84 Coordinate in our country. It's difficult to join and merge of the information among coordinate. And transformations among coordinate systems are always very attractive task in GIS. They play an important role in GIS application. With the more and more wide application of GIS, the accuracy of the transformation is more and more highly required. So the significance of coordinate transformation is more and more distinct.Firstly, we introduce the space reference system and general coordinate simply. The coordinate system transformation method is research .Especial transformation method of different coordinate system, between Geodetic Coordinate and Geocentric Rectangular Coordinate, and from Rectangular Coordinate to Geocentric Geodetic Coordinate. The paper discusses the algorithm model of between WGS-84 coordinate and BJ-54 coordinate. The simple model is useful by some examples. Finally I designed and carried out the coordinate transformation experimental system based on VC++ programmed platform and achieved input and display mode of WINDOWS interfaced, achieved a series of transformation. And I finished basic transformationbetween WGS-84 and BJ-54. 1,(B,L)₈₄——(X,Y,Z)₈₄. Transformation fromGeodetic Coordinate to Geocentric Rectangular Coordinate. 2,( X,Y,Z )₈₄——( X,Y,Z)₅₄. Transformation from datum plane, using Bursa-Wolf algorithm.3,( X,Y,Z)₅₄——( B,L)₅₄. Transformation from Rectangular Coordinate to Geocentric Geodetic Coordinate.4,(B,L)₅₄——(x,y)₅₄ .Gauss projection.