3 . for geographic coordinates and cartesian coordinates transformation a model that include 7 parameters and the guess - kruger projection were used . the difference of calculation between the above method and trimble tgo software is less than 1cm 选用了7参数布尔莎模型进行wgs - 1984空间直角坐标系与北京1954空间直角坐标系之间的转换；使用了高斯-克里格投影进行大地坐标系与平面直角坐标系之间的转换。
