GPS高程拟合在水利测量中的应用研究

Research on the application of GPS elevation fitting in hydrographical surveying

常见高程系统包括大地高、正高及正常高系统,由于GPS测量的大地高在实际测量中的应用十分有限,须采用高程拟合技术,将大地高转换成为正常高,但转换过程中会出现高程异常,因此采用拟合方程对已知高程进行异常处理。高程拟合方法包括多项式与多面函数拟合法,在GPS拟合原理基础上,对二次多项式、三次多项式、多面函数3种拟合方法的高程异常及拟合差值进行分析计算,并将拟合方法应用于地形起伏差异不同的2个测区,对3种拟合方法的精度评定进行比较分析。结果表明:三次多项式拟合方法的精度要优于二次多项式和多面函数的拟合精度,说明三次多项式拟合更适用于水利测绘工程,且通过三次多项式拟合方法可减少水利测量工作,提高测量精度和工作效率。

Common elevation systems include geodetic height,orthometric height,and normal height systems.Due to rare applications of GPS geodetic height in practice,elevation fitting technology must be applied to convert geodetic height to normal height,during which elevation anomalies will occur.Therefore,fitting equations are applied to deal with known elevations.The elevation fitting methods include polynomial and polyhedral function fitting methods.Based on the GPS fitting principle,the height anomalies and fitting differences of the three fitting methods,which are quadratic polynomial,cubic polynomial,and polyhedral function are analyzed and calculated.The fitting methods are applied to two survey areas with different topographic differences,where the evaluation accuracy of the three fitting methods is compared and analyzed.The results show that the accuracy of the cubic polynomial fitting method is better than that of the other two methods,which shows that the cubic polynomial fitting is more suitable for hydrographical surveying and mapping.It leads to a considerable reduction of surveying work and improves surveying accuracy and work efficiency.