共查询到16条相似文献，搜索用时 46 毫秒
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以吉林大学兴城物探教学实习测网为例,基于EGM2008重力场模型,采用二次曲面、移动曲线、最小二乘配置、三次样条和反距离加权改正插值法,计算了不同GPS水准点密度情况下的水准面模型,并利用二等水准测量方法验证了计算精度,分析了该模型的适定性。结果表明,三次样条插值法的精度和稳定性最高,其次是移动曲线法和最小二乘配置法;二次曲面拟合的精度最低,反距离加权改正法稳定性最差。所有算法都表明,在研究区,当GPS水准点间隔20 km时,基于EGM2008模型确定的大地水准面精度在0.1 m以内;而采用单独GPS水准点的区域大地水准面模型能达到14cm,完全满足各种比例尺情况下的石油物探测量要求。 相似文献
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作为GPS/重力边值问题理论及方法的应用,在对GPS/重力方法确定(似)大地水准面的原理进行简要介绍与分析的基础上,利用收集到的N区的600个GPS/重力数据和48个高精度GPS水准数据,计算出该区域的(似)大地水准面。通过拟合法和系统差直接改正法进行的精度分析表明,应用GPS/重力数据结合水准方法确定的该地区(似)大地水准面的精度达到厘米级精度。 相似文献
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CQG2000模型在青藏高原地区的精度检验及其对区域重力调查工作的意义 总被引：1，自引：1，他引：0
区域重力调查中,测点正常高的精度直接影响重力测量成果的精度。利用CQG2000似大地水准面模型对GPS测得的大地高程进行改算,可得到较高精度的正常高成果。然而,CQG2000似大地水准面模型在不同地区的精度和分辨率是不同的,在青藏高原地区精度相对差些。通过对CQG2000似大地水准面模型在青藏高原地区精度的实地检验,证实其在该地区的精度可以满足1:20万区域重力调查工作中求取测点正常高的精度需要。通过上述实验,总结出用CQG2000模型提高区域重力调查中GPS高程测量精度的方法,对区域重力调查工作有重要意义。 相似文献
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区域重力调查中,GPS高程测量的精度直接影响重力测量成果的精度.用国内最新研制的测绘科技成果--CQG2000似大地水准面模型,对GPS测得的大地高程进行改算,可得到较高精度的正常高成果.方法应用于青海三江流域1:20万区域重力调查工作中,取得了较好的效果. 相似文献
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GPS求得的高程是地面点在WGS84坐标系中的大地高,而我国采用正常高系统的高程,是通过该点的大地高减去该点的高程异常获得。高程异常的获取,惯用的做法是曲面拟合法,这种方法在水准点稀少的测区（特别是山区）实施起来比较困难。EGM2008模型是迄今为止分辨率最高、精度最好、阶次最多的全球重力场模型。首先利用EGM20081′×1′的大地水准面模型计算各点的高程异常,再通过联测一个一等水准点,获取EGM2008模型所表示的全球似大地水准面与我国高程基准面之间的差异,即可将GPS大地高转换为1985国家高程基准的正常高。兴城测区实例表明,EGM2008模型高程转换法在山区仅用一个水准点即可实现GPS大地高到正常高的转换,且高效率、高精度。 相似文献
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An improved hybrid gravimetric geoid model for Egypt, EGY-HGM2016, has been recently computed implementing the least-squares collocation (LSC) method through the remove-compute-restore (RCR) procedure. The computation of EGY-HGM2016 involves different datasets in terms of gravity anomalies determined from the GOCE (gravity field and steady-state ocean circulation explorer)-based global geopotential model (SPW-R4) up to d/o 200 and EGM2008 from d/o 201 to 720 combined with terrestrial gravity datasets in terms of 2140 gravity field anomalies and about 121,480 marine surface gravity anomalies. In addition, orthometric heights from 17 GPS/levelling measurements have been considered during the modelling process to improve the determination of the hybrid gravimetric geoid over the Egyptian region. The EGY-HGM2016 model estimated over Egypt provides geoid heights that are ranging from 7.677 to 21.095 m with a standard deviation (st. dev.) of about 2.534 m in the northwest of the country excluding the involvement of the orthometric heights from GPS/levelling measurements. When the later dataset is considered during the implementation of LSC process, hybrid residual height anomalies ranging from ?1.5 to +0.9 m, with a mean of 0.22 m and a st. dev. of 0.17 m, are obtained. Comparison of the predicted hybrid gravimetric geoid with the corresponding ones obtained from EGM2008, GOCE-based SPW R4 model, and GPS/levelling reveals considerable improvements of our EGY-HGM2016 model over Egypt. 相似文献
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New geoid computations for the Hellenic area are carried out using (a) gravity anomalies for the land area available from old and new data bases, and gravity data for the sea area derived from altimetry and a recent digitization of sea gravity maps, and (b) a 1km × 1km digital terrain model. The EGM96 geopotential model is used as the reference field. In order to assess the quality of the computed geoid heights in the continental area comparisons were carried out with GPS/leveling heights and the recently available European Gravimetric Geoid EGG97. In the sea area the geoid heights were compared with sea surface heights of the recent and more accurate TOPEX/POSEIDON (T/P) altimetry mission. At the end of this article the improvement of the data bases is discussed and some plans for further development in the methodological schedule are pointed out. 相似文献
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A local geoid solution for the northern part of Greece is presented based on a recent processing of newly available gravity data in the area 40.25 ≤ /o ≤ 41.00, 22.5 ≤λ ≤ 24.25. The derived gravimetric geoid heights are compared with geoid heights computed at recently measured GPS/ leveling benchmarks. A 4-parameter transformation model is applied to the differences between the two aforementioned geoid height sets, and a discussion is given on the current state of the leveling datum in the test area and the Greek territory. Regional and local transformation parameters are computed and some numerical tests are performed. A common adjustment of gravimetric geoid heights and corresponding GPS/leveling heights will be carried out in another study following an integrated procedure in order to study problems arising from the combination of different height data sets for geoid determination. Finally, some conclusions are drawn on the problems related to the optimization of a local geoid solution. 相似文献
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According to the wide spread use of satellite-based positioning techniques, especially Global Navigation Satellite Systems (GNSS), a greater attention has been paid to the precise determination of geoid models. As it is known, leveling measurements require high cost and long time in observation process that make it not convenient for the practical geodetic purposes. Thus obtaining the orthometric heights by GNSS is the most conventional way of determining these heights. Verifying this goal was the main objective behind the current research. The current research introduces a numerical solution of geoid modeling by applying a surface fitting for a few sparse data points of geoid undulation using minimum curvature surface (MCS). The MCS is presented for deriving a system of linear equations from boundary integral equations. To emphasize the precise applicability of the MCS as a tool for modeling the geoid in an area using GPS/leveling data, a comparison study between EGM2008 and MCS geoid models, is performed. The obtained results showed that MCS technique is a precise tool for determining the geoid in Egypt either on regional and/or local scale with law distortion at check points. 相似文献
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The Fast Fourier Transformation (FFT) has become a routine mathematical tool for the refinement of the Earth's gravity field, such as the computation of precise gravimetric geoid and terrain corrections, particularly over a large area. This paper presents ideas and methodologies to evaluate the accuracy of geoid undulation computations using FFT. A global geopotential model is used as a ‘ground truth’ gravity field model to assess the geoid determination precision by using FFT technique. It is demonstrated that special considerations must be given for a high precision FFT gravimetric geoid determination. A maximum of a few decimetres error could be introduced by the FFT algorithm if the gravity anomalies are not long wavelength filtered and/or no zero padding is applied. 相似文献
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In this paper an estimator for geoid is presented and applied for geoid computation which considers the topographic and atmospheric effects on the geoid. The total atmospheric effect is mathematically developed in terms of spherical harmonics to degree and order 2,160 based on a recent static atmospheric density model. Also the contribution of its higher degrees is formulated. Another idea of this paper is to combine one of the recent Earth gravity models (EGMs) of the Gravity field and steady-state Ocean Circulation Explorer (GOCE) mission with EGM08 and the terrestrial gravimetric data of Fennoscandia in an optimum way. To do so, the GOCE EGMs are compared with the Global Positioning System (GPS)/levelling data over the area for finding the most suited one. This comparison is done in two different ways: with and without considering the errors of the EGMs. Comparison of the computed geoids with the GPS/levelling data shows that a) considering the total atmospheric effect will improve the geoid by about 5 mm, b) GOCO03S is the most suited GOCE EGM for Fennoscandia, c) the errors of some of the GOCE EGMs are optimistic and far from reality. Combination of GOCO03S from degree 120 to 210 and EGM08 for the rest of degrees shows its good quality in these frequencies. 相似文献