似大地水准面模型精度评定方法比较

Comparison of accuracy assessment methods for quasi-geoid model

准确评定似大地水准面模型精度是应用似大地水准面模型的重要参考依据。本文针对现有精度评定方法计算的结果存在差异的问题,分析了各个方法的适用性。首先,利用实测高程异常和模型高程异常的差异分析模型精度,以该精度作为真值,分析空点法、循环空点法和误差特性法在不同地形类型下精度评定结果的可靠性,及在不同地类下的适用性。然后,选取我国三个具有典型地形特征的试验区进行分析,结果表明:在地势平坦、地表类型较为一致的地区,空点法和循环空点法能较好地评价模型精度,空点法对选点要求较高;若地势复杂、地表形态多变,循环空点法确定的精度更为接近实际;误差特性法受地形影响小,计算的精度整体偏高。

Accurately assess the accuracy of the quasi-geoid model is an important reference for its application.As to the problem of the indicator differences calculated by existed accuracy assessment methods,the applicability of each method is analyzed in this paper.The model accuracy is derived from the difference between the measured and the model elevation anomaly,and it is taken as the true value to analyze the reliability of the assessments by the empty point method,the cycling empty point method,and the error characteristic-based method under different terrain types,as well as their applicability under different land types.Three testing areas with typical topographic characteristics in China are selected for analyzing.The results show that in areas with flat terrain and relatively consistent surface types,the empty and the cycling empty point method can be used to evaluate the model accuracy,while the former has higher requirements for point selection.When the terrain is complex and the surface morphology is variable,the accuracy determined by the cycling empty point method is closer to real conditions.The error characteristic-based method is less affected by terrain,and the calculated accuracy by it is relatively higher.