利用EGM2008模型与加权组合模型进行高程异常拟合

高程异常拟合是GPS高程测量应用于实际工作的重要技术手段,高精度地求解高程异常是技术关键。本文提出了顾及EGM2008重力场模型的高程异常拟合方法,通过EGM2008重力场模型计算高程异常长波项,并对剩余高程异常利用加权组合模型进行拟合。通过江苏省某市的实测数据验证顾及EGM2008重力场模型的加权组合模型拟合方法。结果表明,该方法的精度达到了厘米级,高程异常拟合效果最大提升了30%。     

基于EGM2008分析我国沿海陆地和岛礁高程异常

利用EGM2008地球重力场模型计算我国沿海13个省市的高程异常,结合实际的GNSS水准观测数据进行了比较分析,得出了GNSS水准实测的高程异常与EGM2008模型的高程异常之差的标准差是11 cm。     

EGM2008模型在地形测量RTK高程转换中的应用

对于缺乏高程控制点的测区,在确保成果精度的前提下,以EGM2008模型高程异常代替实际高程异常,推导出了大比例尺地形测量RTK高程转换的近似公式及其精度估计公式,并对高程测量限差m、实际高程异常短波部分的平均变化率q和作业距离限制d三者间的关系进行了深入分析。结果表明,在缺乏高程控制点的测区,在作业距离限制范围内开展大比例尺地形测量时,直接利用EGM2008模型进行RTK高程转换,其结果精度能满足有关规范的要求,无需开展更多的水准测量或三角高程测量工作。     

EGM2008重力场模型在RTK高程测量中的应用

由于GPS测量得到的是WGS-84高程,而我国采用正常高系统,使用RTK高程必须进行高程拟合,需要均匀分布测区且数量足够的GPS/水准已知点。在我国大陆,EGM2008重力场模型高程异常总体精度为20cm,提出了将EGM2008模型应用于RTK高程测量的方法,根据实际应用检核结果,RTK单点校正即可达到较高精度。     

地球重力场模型在GPS高程测量中的应用

介绍了地球重力场模型（EGM2008）及其精度,对利用EGM2008模型进行GPS高程测量这一方法进行了探讨。在试验区内采用多种方案进行数据处理,结合试验区内的已有GPS水准点资料的情况进行了分析,通过对多种方案进行比较分析,得出了利用EGM2008模型进行GPS高程测量的精度与采用水准点的大致关系,为GPS高程测量提供一种新思路。     

EGM2008的高程拟合模型在广西区域的应用研究

利用广西2013年测量的部分二等水准测量成果,对EGM2008地球重力场模型1′×1′的模型进行检核,得到其在广西境内的高程异常差值为36.8cm。并选取了广西两个较有代表性区域的数据,使用多种G P S高程多项式拟合的方法以及基于EGM2008地球重力场模型的移去-恢复法进行实验研究,通过数据统计分析,最优拟合模型精度可达到5cm以内,对EGM2008地球重力场模型在广西的实际应用得到了一些非常有意义的结论。     

组合重力场模型的精度及其适用性分析

针对EGM2008、GECO及EIGEN-6C4重力场模型存在长波误差的情况,利用GNSS/水准数据在分析EGM2008、GECO及EIGEN-6C4模型高程异常精度基础上,分析GOCO03S、GO_CONS_GCF_2_DIR_R5、GO_CONS_GCF_2_SPW_R2、GO_CONS_GCF_2_TIM_R5 4个纯卫星重力场模型与EGM2008、GECO及EIGEN-6C4模型在不同阶次组合的精度,进而选取可靠的截断阶次确定组合重力场模型。计算结果表明:与EGM2008、GECO及EIGEN-6C4模型相比,各自对应的组合重力场模型高程异常精度最优分别可达0.061m、0.054m和0.059m,对应精度提升幅度分别为18%、31%和24%,因此,组合重力场模型能提高重力场模型高程异常的精度;利用EGM2008、GECO及EIGEN-6C4模型进行高程拟合的精度与利用组合重力场模型进行高程拟合的精度相当,这说明EGM2008、GECO及EIGEN-6C4模型存在的长波段误差也可通过一定的拟合模型进行削弱。     

在小区域内利用EGM2008重力场模型进行GPS高程转换的应用分析

简要介绍了EGM2008全球重力场模型,以及利用EGM2008模型计算地面点高程异常的原理,指出了在已知GPS控制网内一点正常高的情况下,如何应用该模型通过计算高程异常进而推算网内各点正常高的方法。结合在冀东某地山区和海滨的两个实验区数据,对使用上述GPS高程转换方法所能达到的精度进行了分析,结论认为在小区域内可以达到四等水准测量精度。     

EGM 2008重力场模型的高程异常精度分析

利用两条设计铁路的GPS水准点数据,对EGM2008模型解算的高程异常进行精度统计分析。结果表明,EGM2008模型解算的高程异常在地形平缓的地区精度优于地形起伏较大的山区,且在两个实验区中误差都优于±10 cm。结合一定数量的GPS水准数据,可用于1:2 000航测地形图外控点的高程拟合。     

基于EGM96模型的GPS水准拟合方法

用GPS测量的方法来获得一点的正高或正常高，需要知识一点的大地水准面差距或高程异常。采用的大地水准面差距或高程异常的精度，决定了GPS水准的精度。本文利用EGM96模型计算高程异常。在利用巳知水准点上的高程异常拟合区域大地水准面模型时，首先移去用EGM96模型计算得到的部分，然后对剩余的高程异常进行拟合和内插，在内插点上再利用EGM96模型把移去的部分恢复，得到该点的高程异常。通过对某线路GPS水准的计算表明，引入EGM96模型拟合高程的精度改进不大。但对于大范围测量，这种方法有望能改进GPS水准的拟合精度。     

Prediction of vertical deflections from high-degree spherical harmonic synthesis and residual terrain model data

This study demonstrates that in mountainous areas the use of residual terrain model (RTM) data significantly improves the accuracy of vertical deflections obtained from high-degree spherical harmonic synthesis. The new Earth gravitational model EGM2008 is used to compute vertical deflections up to a spherical harmonic degree of 2,160. RTM data can be constructed as difference between high-resolution Shuttle Radar Topography Mission (SRTM) elevation data and the terrain model DTM2006.0 (a spherical harmonic terrain model that complements EGM2008) providing the long-wavelength reference surface. Because these RTM elevations imply most of the gravity field signal beyond spherical harmonic degree of 2,160, they can be used to augment EGM2008 vertical deflection predictions in the very high spherical harmonic degrees. In two mountainous test areas—the German and the Swiss Alps—the combined use of EGM2008 and RTM data was successfully tested at 223 stations with high-precision astrogeodetic vertical deflections from recent zenith camera observations (accuracy of about 0.1 arc seconds) available. The comparison of EGM2008 vertical deflections with the ground-truth astrogeodetic observations shows root mean square (RMS) values (from differences) of 3.5 arc seconds for ξ and 3.2 arc seconds for η, respectively. Using a combination of EGM2008 and RTM data for the prediction of vertical deflections considerably reduces the RMS values to the level of 0.8 arc seconds for both vertical deflection components, which is a significant improvement of about 75%. Density anomalies of the real topography with respect to the residual model topography are one factor limiting the accuracy of the approach. The proposed technique for vertical deflection predictions is based on three publicly available data sets: (1) EGM2008, (2) DTM2006.0 and (3) SRTM elevation data. This allows replication of the approach for improving the accuracy of EGM2008 vertical deflection predictions in regions with a rough topography or for improved validation of EGM2008 and future high-degree spherical harmonic models by means of independent ground truth data.     

Evaluation of EGM 2008 with EGM96 and its Utilization in Topographical Mapping Projects

Precise terrain elevation information is required in various remote sensing and Engineering projects. There are many technologies to derive the terrain elevation information like GPS, ground surveys, LiDAR, Photogrammetry. GPS is the most widely used technology to obtain information due to its ease of operation. However the usage of ellipsoidal heights, i.e. with respect to WGS84 has limited usage in hydrological applications. GPS heights must be converted into orthometric heights for use in hydrological applications, and this requires geoid undulation information. These geoid undulations can be deduced from earth gravity models. There are various earth gravity models available for ready usage like EGM96, EGM2008, GFZ96 in the public domain. This paper discusses the improvements observed in deriving orthometric heights using EGM2008 over its predecessor model EGM96. The utilization of the new model in topographical mapping projects are also presented.     

Combining EGM2008 and SRTM/DTM2006.0 residual terrain model data to improve quasigeoid computations in mountainous areas devoid of gravity data

A global geopotential model, like EGM2008, is not capable of representing the high-frequency components of Earth’s gravity field. This is known as the omission error. In mountainous terrain, omission errors in EGM2008, even when expanded to degree 2,190, may reach amplitudes of 10 cm and more for height anomalies. The present paper proposes the utilisation of high-resolution residual terrain model (RTM) data for computing estimates of the omission error in rugged terrain. RTM elevations may be constructed as the difference between the SRTM (Shuttle Radar Topography Mission) elevation model and the DTM2006.0 spherical harmonic topographic expansion. Numerical tests, carried out in the German Alps with a precise gravimetric quasigeoid model (GCG05) and GPS/levelling data as references, demonstrate that RTM-based omission error estimates improve EGM2008 height anomaly differences by 10 cm in many cases. The comparisons of EGM2008-only height anomalies and the GCG05 model showed 3.7 cm standard deviation after a bias-fit. Applying RTM omission error estimates to EGM2008 reduces the standard deviation to 1.9 cm which equates to a significant improvement rate of 47%. Using GPS/levelling data strongly corroborates these findings with an improvement rate of 49%. The proposed RTM approach may be of practical value to improve quasigeoid determination in mountainous areas without sufficient regional gravity data coverage, e.g., in parts of Asia, South America or Africa. As a further application, RTM omission error estimates will allow refined validation of global gravity field models like EGM2008 from GPS/levelling data.     

EGM2008在GPS高程拟合中的应用研究

西南边境地区地形复杂、山高坡陡、交通不便,采用常规的水准测量方法测量极为困难。本文引入最新的EGM2008地球重力场模型用于西南边境地区的GPS高程拟合,并探讨与分析了基于EGM2008地球重力场模型的高程拟合精度。本文以云南省"兴地睦边"农田整治重大项目中的某高山地测区为例,结合常规高程拟合数学模型与EGM2008地球重力场模型,建立区域似大地水准面精化模型进行GPS高程拟合,其结果与常规高程拟合数学模型的结果进行对比分析。     

EGM 2008模型的无验潮测深技术

针对无验潮测深技术高程基准转换的精度和复杂性问题,该文提出基于EGM 2008模型的无验潮测深技术,从而解决无验潮测深经GNSS测得的瞬时WGS-84的参考椭球高向正常高转换难题。经测试,EGM 2008仅利用少量控制点修正系统偏差后,就可以满足长距离低等级的水准测量精度要求。将EGM 2008模型应用于无验潮测深,坐标转换误差和无验潮测深精度均达到cm级,突破无验潮测深高程基准转换的瓶颈,实现实时、高效、高精度的无验潮测深。     

基于EGM2008地球重力场模型的GPS高程转换研究

综合利用EGM2008地球重力场模型,采用＂移去-拟合-恢复＂方法和二次曲面函数数值逼近算法进行GPS高程转换。通过某隧道实例验证了＂移去-拟合-恢复＂的有效性和实用性,检验了EGM2008地球重力场模型的精度。通过计算比较,在测区范围内,合理选择均匀分布的GPS/水准点,可以使高程拟合精度达到最大。     

利用EGM2008模型估算海洋重力测量测线布设间距

测线布设是海洋重力测量中海区技术设计的主要内容,在保证测图精度和提高测量效率方面起着关键作用。目前测线间距依据测量任务而定,没有充分顾及测区重力异常的变化特性。结合海洋重力测量的特点,利用EGM2008模型重力异常作为测线布设的先验信息,在满足测量成果精度要求的前提下,估算测线布设间距。利用实测数据检验估算的测线布设间距的合理性,结果表明,利用EGM2008模型估算的测线间距布设测线能满足海洋重力测量的精度要求,为确定海洋重力测量测线布设间距提供量化依据。