陕西省实用化似大地水准面模型建立及验证

Establishment and verification of a practical quasi-geoid model in Shaanxi province

针对遥感影像处理中存在密集要素点的大地高换算为正常高的问题,该文提出一种便捷确定要素点高程异常的方法。利用似大地水准面模型计算图幅中心点高程异常及梯度信息,建立高程异常与梯度信息结合的实用化似大地水准面模型;构建要素点正常高精度与图幅高程异常梯度的关系,判断实用化似大地水准面模型在不同图幅中的适用性。计算陕西省似大地水准面模型梯度,确定实用化似大地水准面模型在陕西省不同图幅中的适用性,并利用4幅不同地类的高分七号卫星遥感数据进行验证。结果表明:陕西省1∶10 000比例尺绝大数图幅满足梯度限差要求,仅在渭南南部地区存在少数图幅超限;利用实用化似大地水准面模型实现数字高程模型正常高获取,实用化模型与原模型互差精度不大于±0.11 m,解决了超限图幅的高程转换问题,满足1∶10 000比例尺测图高程精度要求。

Aiming at the problem of converting the ellipsoid height of dense points to normal height in remote sensing image processing,a convenient method for determining the height anomaly of points was proposed.Firstly,the height anomaly and the gradient information of the map center could be computed with the quasi-geoid model,and the practical quasi-geoid model was established with height anomaly and gradient information.Secondly,the relationship between the normal height accuracy of points and the height anomaly gradient of the map was determined.Finally,the applicability of the practical geoid model in different map could be judged.The gradient of the quasi-geoid model of Shaanxi Province was calculated,and the applicability of the practical quasi-geoid model in different maps of Shaanxi Province was determined by comparing with the gradient limit.The 4 maps of GF-7 Satellite remote sensing data with different geographic types were used for verification of the practical quasi-model applicability.The results showed that most gradient of 1∶10000 maps in Shaanxi province could meet the tolerance except few areas in the south of Weinan.The normal height of digital elevation model was efficiently transformed with the practical geoid model,and the relative accuracy between the practical model and the original model was smaller than±0.11 m.Therefore,the problem exceeding the tolerance was solved with the practical geoid model,all result could meet the limit of elevation accuracy for 1∶10000 DEM.