共查询到20条相似文献，搜索用时 468 毫秒
1.
本文利用全球重力位模型、胶州市地面重力观测数据、胶州市GPS水准数据和数字地面模型(DTM),采用组合法应用移去-恢复技术计算剩余大地水准面,并与地球位模型计算的高程异常进行拟合,得到该地区重力似大地水准面,再和布测、计算得到的GPS/水准所构成的几何大地水准面拟合,利用多项式拟合完成系统改正,获得最终的大地水准面结果及相关的精度信息。 相似文献
2.
本文利用全球重力位模型、胶州市地面重力观测数据、胶州市GPS水准数据和数字地面模型(DTM),采用组合法应用移去-恢复技术计算剩余大地水准面,并与地球位模型计算的高程异常进行拟合,得到该地区重力似大地水准面,再和布测、计算得到的GPS/水准所构成的几何大地水准面拟合,利用多项式拟合完成系统改正,获得最终的大地水准面结果及相关的精度信息。 相似文献
3.
利用空中平均重力异常确定区域大地水准面 总被引：3，自引：0，他引：3
提出了直接利用空中平均重力异常计算区域大地水准面的方法。模拟计算的结果表明, 该方法与传统的利用地面平均空间重力异常确定的大地水准面精度相当, 但其显著优点是勿需空中重力异常的向下解析延拓, 从而可以避免延拓误差对大地水准面精化的影响。 相似文献
4.
缺乏有效的大地水准面成果精度评估方法,是高程基准现代化及其成果应用面临的关键问题。本文基于GNSS水准高程异常与重力场频域误差特性,研究GNSS水准与重力地面高程异常融合的技术要求,进而提出一种大地水准面成果的误差表达与精度评估方法。经示例测试分析,得出主要结论如下:①实用地面高程异常(即融合后的似大地水准面)精度,应采用随距离非线性变化的高程异常差误差曲线表达;②似大地水准面的精度评估,推荐采用两项误差指标和两条误差曲线共4个要素完整表达,即重力地面高程异常差误差、实用地面高程异常内部误差、实用地面高程异常差误差曲线与GNSS水准高程异常差误差曲线;③当两个GNSS水准点间距离接近或小于所有GNSS水准点平均间距时,GNSS水准高程异常对实用地面高程异常的贡献起主要作用;④较大空间尺度的实用地面高程异常精度主要依靠重力地面高程异常控制。 相似文献
5.
应用GPS水准与重力数据联合解算大地水准面 总被引：1，自引：0，他引：1
GPS水准大地水准面与重力大地水准面之差不仅由基准不同引起,而且也包含重力与GPS水准观测值的误差。建立了这两个水准面之差与基准转换参数、重力和GPS水准观测值的残差之间的关系,并基于最小二乘准则解算了基准转换参数和重力与GPS水准观测值的残差,即计算转换参数及重力与GPS观测值的改正。尤其当GPS水准精度远高于重力水准面时,联合解算模型可固定GPS水准大地水准面,只对重力观测值进行改正。 相似文献
6.
区域重力大地水准面确定的相对精度估计 总被引：2，自引：1，他引：1
以频域解析方法,研究由地面重力数据、全球住模型确定区域重力大地水准面的相对精度估计.首先由Stokes公式的数值积分推导地面重力数据与球谐系敬的精度关系;再由"移去-恢复"方法的空域截断逼近模式和协方差函数的球谐表达,分别推导内区地面重力数据之误差、外区全球位模型之误差与区域重力大地水准面之相对精度的解析关系;为便于计算,提出将内区地面重力数据和外区全球位模型的频域截断误差合并,再按频段重新划分为两部分:①全球范围--地面重力数据对应频率以上的截断;②外区范围--介于全球位模型最高频率与地面重力数据对应频率之间的截断,以经验阶方差模型分别估计之.模拟计算显示了地面重力数据之精度、分辨率、积分半径和全球位模型之精度、分辨率与区域重力大地水准面之相时精度的具体对应关系.本文研究同样适用于区域重力似大地水准面的确定. 相似文献
7.
8.
P. Novak M. Kern K.-P. Schwarz M. G. Sideris B. Heck S. Ferguson Y. Hammada M. We 常晓涛 《测绘文摘》2003,(2)
随着近年来航空重力的发展,航空重力数据的精度和分辨率不断提高,其精度可达1 mGal,分辨率可达10km,这使得用航空重力数据计算精密大地水准面成为可能。本研究介绍利用满足一定条件的稳定、精确的航空重力数据计算大地水准面的一种新途径。它根据布隆公式,分离大地水准面与参考椭球,把航空重力观测值转换为大地水准面上的重力位,从而确定大地水准面。其具体步骤如下: 1.对重力扰动观测数据进行低通滤波,除去高频观测噪声; 2.利用全球重力场模型从低通滤波的重力 相似文献
9.
为提高利用逆Stokes公式反演测高重力的精度,将中央区大地水准面高表示成双三次多项式插值形式,引入了非奇异变换,推导出了重力异常的计算公式。大地水准面高理论模型下的分析表明,该公式有较高的精度。以分辨率为2′×2′的大地水准面高数据为背景场进行了实际计算,结果说明中央区对反演重力异常有不容忽视的贡献。本文导出的公式可为高精度重力异常的反演提供理论依据。 相似文献
10.
中国新一代高精度、高分辨率大地水准面的研究和实施 总被引：13，自引：2，他引：13
采用移去恢复技术，利用我国高分辨率DTM和重力资料推算我国大陆重力大地水准面;然后再和我国GPS水准所构成的高程异常控制网拟合,推算了具有dm级精度、15′×15′分辨率的我国大陆大地水准面。利用全国地壳运动监测网络的80余个高精度GPS水准点进行外部检核，检核结果证实和原设计精度完全一致，即该大陆大地水准面的绝对精度,在东经102°以东高于±0.3m，在东经102°以西、北纬36°以北为±0.4m，36°以南为±(0.4～0.6)m。利用卫星测高数据计算垂线偏差，反解我国海域大地水准面。为了检核，由测高垂线偏差反演为重力异常，与海上万余点船测重力值进行了外部检核；同时用上述反演的重力异常推算大地水准面，与直接解得的相应结果进行比较作为内部检核。由重力和GPS水准数据推算的上述大陆大地水准面，和主要由卫星测高数据确定的海洋大地水准面，二者之间一般都存在以系统误差为主的拼接差。顾及这一现象并结合我国在陆海大地水准面拼接区重力资料稀疏的实际，研究提出了扩展拼接技术，即在沿海选取部分陆海毗邻的局部地区，在这局部地区内，陆地用实测平均重力格网数据，海洋用测高平均重力格网数据，统一推算这陆海局部重力大地水准面。然后利用这一局部大地水准面的陆地部分和已经用GPS水准校正的陆地大地水准面进行拟合。最后用拟合参数校正中国全部海域的测高重力大地水准面，从而保持陆地部分大地水准面不变，最大限度地削弱拼接点和测高海洋大地水准面的系统误差。 相似文献
11.
R. Kiamehr 《Journal of Geodesy》2006,79(10-11):602-612
The computation of regional gravimetric geoid models with reasonable accuracy, in developing countries, with sparse data is a difficult task that needs great care. Here we investigate the procedure for gathering, evaluating and combining different data for the determination of a gravimetric geoid model for Iran, where limited ground gravity data are available. Heterogeneous data, including gravity anomalies, the high-resolution Shuttle Radar Topography Mission global digital terrain model and different global geopotential models including recently published Gravity Recovery and Climate Experiment models, are combined through least-squares modification of the Stokes formula. The new gravimetric geoid model, IRG04, agrees considerably better with GPS/levelling than any of the other recent local geoid model in the area. Its RMS fit with GPS/levelling is 0.27 m and 3.8 ppm in the absolute and relative view, respectively. The relative accuracy of IRG04 is four times better than the most recently published global and regional geoid models available in this area. This progress shows the practical potential of the method of least-squares modification of Stokes’s formula in combination with heterogeneous data for regional geoid determination 相似文献
12.
GPS-levelling points are widely used to control gravimetric geoid or quasigeoid models. Direct comparison is often interpreted
to reveal the accuracy of the gravimetric model, using GPS-levelling as a reference. However, both GPS and levelled heights
contain errors, and in order to achieve a centimeter-accuracy geoid, these should be investigated. The Norwegian Height System
NN1954 is known to contain large systematic errors due to postglacial land uplift in the area. In this study, the current
height system and two revised versions, corrected for uplift, are applied to compute three sets of control quasigeoid heights
in the southern part of Norway. These heights are then compared to various Nordic gravimetric quasigeoid models generated
during the last two decades. In contradiction to some earlier studies, the accuracy of gravimetric quasigeoid models for this
area are found to improve near-linearly with time. This is in accordance with expectations, since both data coverage and computation
methods have progressed during this time. However, this study shows the importance of establishing accurate and error-free
control data for geoid comparisons. 相似文献
13.
EGM96,WDM94和GPM98CR高阶地球重力场模型表示深圳局部重力场的比较与评价 总被引：9，自引：0，他引：9
为计算深圳精密重力大地水准面，利用62个高精度GPS水准点和4871个实测重力点数据对EGM96，WDM94和GPM98CR全球重力场模型表示深圳局部重力场进行了比较与评价。结果表明，由上述3个重力场模型计算的大地水准面高和重力异常与实测值之间存在明显的系统偏差，当采用GPS水准数据尽可能消除系统偏差以后，大地水准面高的精度得到显著提高，若应用移去-恢复技术确定深圳高精度大地水准面，则WDM94应该是首选的参考重力场模型。 相似文献
14.
GPS水准、天文重力水准与重力大地水准面多种数据联合处理的研究 总被引：1，自引：0，他引：1
针对我国大地水准面的研究状况，提出了在国家ＧＰＳＢ级网完成之后，利用ＧＰＳ水准、天文重力水准与重力大地水准面３类数据确定我国高精度大地水准面的理论和方法。分析了３类数据的误差传播规律，给出了联合平差模型，并用一模拟网进行了试算 相似文献
15.
Essam Ghanem 《地球空间信息科学学报》2013,16(1):19-23
The main objective of this study is to improve the geoid by GPS/leveling data in Egypt. Comparisons of the gravimetric geoid with GPS/leveling data have been performed. On the basis of a gravimetric geoid fitted to GPS/leveling by the least square method, a smoothed geoid was obtained. A high-resolution geoid in Egypt was computed with a 2.5′×2.5′ grid by combining the data set of 2600 original point gravity values, 20″×30″ resolution Digital Terrain Model (DTM) grid and the spherical harmonic model EGM96. The method of computation involved the strict evaluation of the Stokes integral with 1D-FFT. The standard deviation of the difference between the gravimetric and the GPS/leveling geoid heights is ±0.47 m. The standard deviation after fitting of the gravimetric geoid to the GPS/leveling points is better than ±13 cm. In the future we will try to improve our geoid results in Egypt by increasing the density of gravimetric coverage. 相似文献
16.
Essam Ghanem 《地球空间信息科学学报》2001,4(1):19-23
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17.
A method is presented with which to verify that the computer software used to compute a gravimetric geoid is capable of producing
the correct results, assuming accurate input data. The Stokes, gravimetric terrain correction and indirect effect formulae
are integrated analytically after applying a transformation to surface spherical coordinates centred on each computation point.
These analytical results can be compared with those from geoid computation software using constant gravity data in order to
verify its integrity. Results of tests conducted with geoid computation software are presented which illustrate the need for
integration weighting factors, especially for those compartments close to the computation point.
Received: 6 February 1996 / Accepted: 19 April 1997 相似文献
18.
Many regions around the world require improved gravimetric data bases to support very accurate geoid modeling for the modernization
of height systems using GPS. We present a simple yet effective method to assess gravity data requirements, particularly the
necessary resolution, for a desired precision in geoid computation. The approach is based on simulating high-resolution gravimetry
using a topography-correlated model that is adjusted to be consistent with an existing network of gravity data. Analysis of
these adjusted, simulated data through Stokes’s integral indicates where existing gravity data must be supplemented by new
surveys in order to achieve an acceptable level of omission error in the geoid undulation. The simulated model can equally
be used to analyze commission error, as well as model error and data inconsistencies to a limited extent. The proposed method
is applied to South Korea and shows clearly where existing gravity data are too scarce for precise geoid computation. 相似文献
19.
2020珠峰高程测量,首次确定并发布了基于国际高程参考系统(IHRS)的珠峰正高。在珠峰地区实现国际高程参考系统,采用的方案是建立珠峰区域高精度重力大地水准面。利用地球重力场谱组合理论和基于数据驱动的谱权确定方法,测试优选参考重力场模型及其截断阶数和球冠积分半径等关键参数,联合航空和地面重力等数据建立了珠峰区域重力似大地水准面模型,61点高精度GNSS水准高程异常检核表明,模型精度达3.8 cm,加入航空重力数据后模型精度提升幅度达51.3%。提出顾及高差改正的峰顶高程异常内插方法,采用顾及地形质量影响的高程异常——大地水准面差距转换改正严密公式,使用峰顶实测地面重力数据,基于国际高程参考系统定义的重力位值W0和GRS80参考椭球,最终确定了国际高程参考系统中的高精度珠峰峰顶大地水准面差距。 相似文献
20.
On the adjustment of combined GPS/levelling/geoid networks 总被引：12，自引：7，他引：5
A detailed treatment of adjustment problems in combined global positioning system (GPS)/levelling/geoid networks is given.
The two main types of `unknowns' in this kind of multi-data 1D networks are usually the gravimetric geoid accuracy and a 2D
spatial field that describes all the datum/systematic distortions among the available height data sets. An accurate knowledge
of the latter becomes especially important when we consider employing GPS techniques for levelling purposes with respect to
a local vertical datum. Two modelling alternatives for the correction field are presented, namely a pure deterministic parametric
model, and a hybrid deterministic and stochastic model. The concept of variance component estimation is also proposed as an
important statistical tool for assessing the actual gravimetric geoid noise level and/or testing a priori determined geoid
error models. Finally, conclusions are drawn and recommendations for further study are suggested.
Received: 9 September 1998 / Accepted: 8 June 1999 相似文献