通过计算机代数系统Mathematica推导出了以地心纬度、归化纬度为变量的卯酉圈曲率半径、子午圈曲率半径和平均曲率半径的直接表达式,该表达式适用于任何椭球参数,具有通用性.并将常规的基于第一偏心率e表示的公式改写为基于第三扁率n表示的公式,以2000国家大地坐标系(China Geodetic Coordinate System 2000,CGCS2000)椭球为例分析了推导出的直接表达式的精确性和可靠性.经分析可得,常用曲率半径展开至e6 或n3 时,既能满足大地测量学要求的精度,也更为紧凑简练,一定程度上提高了地图投影的计算效率.
Direct Expansions for Common Curvature Radii in Terms of Different Latitude Variables
With the computer algebra system Mathematica,the direct calculation formulas of radius of curvature in prime vertical,meridian radius of curvature,mean radius of curva-ture are derived,which take geocentric latitude and reduced latitude as variables.The expressions can be applied to any el-lipsoid parameter for their universality.The conventional for-mula based on the first eccentricity e is rewritten to the formu-la based on the third oblate n,and China Geodetic Coordinate System 2000(CGCS2000)ellipsoid is used to analyze the accuracy and reliability of the derived direct expressions.The analysis result shows that when the curvature radii are ex-panded to e6 or n3,the accuracy of geodesy can be satisfied,and the calculation efficiency of map projection can be im-proved to some extent.
meridian radius of curvatureradius of curvature in prime verticalmean radius of curvaturereduced latitudegeocentric latitudecomputer algebra system