scholarly journals Preliminary Unification of Kronsztadt86 Local Vertical Datum with Global Vertical Datum

2015 ◽  
Vol 97 (1) ◽  
pp. 103-111 ◽  
Author(s):  
Adam Łyszkowicz ◽  
Joanna Kuczyńska-Siehień ◽  
Monika Biryło
Keyword(s):  
Systematic Error ◽  
Sufficient Accuracy ◽  
Satellite Networks ◽  
Satellite Observations ◽  
Gravity Potential ◽  
Best Value ◽  
Vertical Datum ◽  
Normal Heights ◽  
Low Efficiency ◽  
Local Vertical Datum

AbstractThe study concerns computation of the gravity potential difference between the Kronsztadt86 datum and the global vertical datum. This method is based on the use of ellipsoidal heights from satellite observations, normal heights obtained from the conducted leveling campaign and quasigeoid/ellipsoid separations computed based on the EGM2008 model. The obtained results indicate that there are substantial differences in the estimated value of the parameter ΔW, computed from three different satellite networks: POLREF, EUVN-DA and ASG-EUPOS. The parameter was determined with sufficient accuracy and the applied systematic error model has low efficiency. The computations reveal that the best value of ΔW for the territory of Poland is 0.43 m2s-2.

scholarly journals A Quasigeoid-Derived Transformation Model Accounting for Land Subsidence in the Mekong Delta towards Height System Unification in Vietnam

2020 ◽  
Vol 12 (5) ◽  
pp. 817
Author(s):  
Dinh Toan Vu ◽  
Sean Bruinsma ◽  
Sylvain Bonvalot ◽  
Dominique Remy ◽  
Georgios S. Vergos
Keyword(s):  
Mekong Delta ◽  
Equipotential Surface ◽  
Transformation Model ◽  
Gravity Potential ◽  
Third Order ◽  
Vertical Datum ◽  
Height System ◽  
Gravimetric Quasigeoid ◽  
Local Vertical Datum

A vertical offset model for Vietnam and its surrounding areas was determined based on the differences between height anomalies derived from 779 Global Navigation Satellite System (GNSS)/levelling points and those derived from a dedicated high-resolution gravimetric-only quasigeoid model called GEOID_LSC. First, the deterministic transformation model to effectively fit the differences between the quasigeoid and GNSS/levelling heights was based on a third-order polynomial model. Second, the residual height anomalies have been interpolated to a grid employing Least-Squares Collocation. Finally, the distortions were restored to the residual grid. This model can be used for combination with a gravimetric quasigeoid model in GNSS levelling. The quality of GNSS/levelling data in Vietnam was analyzed and evaluated in this study. The annual subsidence rate from ALOS-1 was also used to analyze the effects of subsidence on the quality of GNSS/levelling data in the Mekong Delta. From this we made corrections to improve the accuracy of GNSS/levelling data in this region. The offset model was evaluated using cross-validation technique by comparing with GNSS/levelling data. Results indicate that the offset model has a standard deviation of 5.9 cm in the absolute sense. Based on this offset model, GNSS levelling can be carried out in most of Vietnam’s territory complying third-order levelling requirements, while the accuracy requirements for fourth-order levelling networks is met for the entire country. This model in combination with the developed gravimetric quasigeoid model should also contribute to the modernization of Vietnam’s height system. We also used high-quality GNSS/levelling data and the determined quasigeoid model to determine the geopotential value W0 for the Vietnam Local Vertical Datum. The gravity potential of the Vietnam Local Vertical Datum is estimated equal to W 0 LVD = 62,636,846.81 ± 0.70 m2s−2 with the global equipotential surface realized by the conventional value W0 = 62,636,853.4 m2s−2.

scholarly journals Estimation of vertical datum offset for the South African vertical datum, in relation to the international height reference system

2021 ◽  
Vol 65 (02) ◽  
pp. 282-297
Author(s):  
Matthews Siphiwe Mphuthi ◽  
Patroba Achola Odera
Keyword(s):  
South Africa ◽  
South African ◽  
Reference System ◽  
Tide Gauge ◽  
Cape Town ◽  
Gravity Potential ◽  
The South ◽  
Vertical Datum ◽  
Port Elizabeth ◽  
Local Vertical Datum

The vertical offset and the geopotential value over South Africa is estimated on the four fundamental benchmarks in relation to the international height reference system (IHRS). It is estimated to obtain discrepancies between the South African local vertical datum (W_P) and the global vertical datum (W_0). A single-point-based geodetic boundary value problem (GBVP) approach was used following Molodensky theory for estimating the height anomalies from the disturbing potential (T_P) using Bruns’s formula. The gravity potential at each tide gauge benchmark (TGBM) in South Africa deviates from the potential of the global reference surface by 0.589,-1.993,-2.593 and 2.154 m2s-2 for Cape Town, Port Elizabeth, East London and Durban, respectively. The corresponding vertical datum offsets between the international height reference system and the four fundamental benchmarks over South Africa are 6.013, -20.347, -26.478, and 21.996 cm for Cape Town, Port Elizabeth, East London and Durban, respectively. These offsets can be used for the unification of the South African vertical datum at the four tide gauge benchmarks in a manner that is consistent to the international height reference system.

scholarly journals Combined approach for the unification of levelling networks in New Zealand

2011 ◽  
Vol 1 (4) ◽  
pp. 324-332 ◽  
Author(s):  
Robert Tenzer ◽  
Viliam Vatrt ◽  
Luzi Gan ◽  
Ahmed Abdalla ◽  
Nadim Dayoub
Keyword(s):  
New Zealand ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Combined Approach ◽  
Network Adjustment ◽  
The North ◽  
Geoidal Geopotential ◽  
Normal Heights ◽  
Orthometric Heights ◽  
Local Vertical Datum

Combined approach for the unification of levelling networks in New ZealandThe unification of levelling networks in New Zealand is done using a combined approach. It utilises the joint levelling network adjustment and the geopotential-value approach. The levelling and normal gravity data are used for a joint adjustment of the levelling networks at the South and North Islands of New Zealand while fixing the heights of tide gauges in Dunedin and Wellington. The results reveal a good quality of levelling data; the STD of residuals is 2 mm for the whole country. The comparison of the newly determined and original normal-orthometric heights confirms the presence of large local vertical datum offsets and systematic levelling errors. Since the geopotential-value approach is based on the Molodensky's theory, the newly adjusted normal-orthometric heights are converted to the normal heights. This conversion is based on applying the cumulative normal to normal-orthometric height correction computed from levelling and gravity anomaly data. In the absence of the observed gravity data the gravity anomalies along levelling lines are generated fromEGM2008. The GPS-levelling data and EGM2008 are used to estimate the average offsets of the jointly adjusted levelling networks at the North and South Islands with respect to World Height System defined by the adopted geoidal geopotential value of W0 = 62636856 ± 0.5 m2s-2; the estimated offsets are 10.6 cm and 27.5 cm.

scholarly journals Interpolation Grid for Local Area of Iasi City

2014 ◽  
Vol 8 (1) ◽  
pp. 157-164
Author(s):  
Raluca Maria Mihalache ◽  
Andreea Manescu
Keyword(s):  
Unitary Transformation ◽  
National Level ◽  
Local Area ◽  
Sufficient Accuracy ◽  
Reference Surface ◽  
National Agency ◽  
Land Registration ◽  
Height System ◽  
Normal Heights ◽  
Interpolation Grid

Abstract Definitive transition to GNSS technology of achieving geodetic networks for cadastre implementation in cities and municipalities, enforce establishing a unique way of linking between current measurements and existing geodetic data, with a sufficient accuracy proper to urban cadastre standards. Regarding city of Iasi, is presented a different method of transformation which consist in an interpolation grid for heights system. The Romanian national height system is „Black Sea-1975” normal heights system. Founded in 1945 by Molodenski, this system uses the quasigeoid as reference surface, being in relation with the ellipsoid through the height anomalies sizes in each point. The unitary transformation between the ETRS- 89 ellipsoidal height system and the normal one, at national level is provided through the „TransdatRo” program developed by NACLR (National Agency for Cadastre and Land Registration).

Statistical techniques and Doppler satellite positioning

1980 ◽  
Vol 294 (1410) ◽  
pp. 365-375
Keyword(s):  
Confidence Regions ◽  
Satellite Networks ◽  
Satellite Observations ◽  
Statistical Techniques ◽  
Satellite Positioning ◽  
Final Development ◽  
Station Coordinates ◽  
Bonferroni's Inequality ◽  
Observation Space ◽  
Detection Of Outliers

Two problems are addressed: ( a ) the detection of outliers in (Doppler satellite) observations, and ( b ) the testing of coordinates in (Doppler satellite) networks. In both problems, confidence regions of the ‘out of context’ and ‘within context’ varieties are developed, and it is shown that the latter are in general about 1 1/2 times larger than the former (conventional) confidence regions. On the basis of this comparison, it is speculated that good data and results are being erroneously rejected. Also it is demonstrated, through the use of Bonferroni’s inequality, that discarding covariances among residuals and discarding cross-covariances among station coordinates each results in a confidence level being greater than 1 — x, the conventionally chosen level. As a final development, a link is made not only between univariate and multivariate testing for outliers among observations but also between testing in observation space and testing in parameter space. The implications of these developments for Doppler satellite positioning are given.

scholarly journals Risk Factors and Potential Solutions for the Construction Industry in China

2020 ◽  
Vol 10 (2) ◽  
pp. 34-47
Author(s):  
Yutian Chen ◽  
Oswald Chong
Keyword(s):  
Developing Countries ◽  
Construction Industry ◽  
Poor Quality ◽  
Kingdom Of Saudi Arabia ◽  
Best Value ◽  
Low Efficiency ◽  
And Performance ◽  
Scheduled Time ◽  
Developed Nations

The Chinese construction industry (CCI) has grown to be one of the largest in the world within the last 10 years. The size of the CCI is on par with many developed nations, despite it being a developing country. Despite its rapid growth, the productivity and profitability of the CCI is low compared to similar sized construction industries. In addition to the low efficiency of the CCI, the minimal documented performance information collected, shows projects being completed over budget, over the scheduled time, with poor quality of work. A literature research was performed on other developing countries similar to the CCI, to identify if there were any solutions that had been proven to improve the productivity and performance of a construction industry. It was found that Vietnam, The Kingdom of Saudi Arabia and India were the closest to China with enough documentation on their construction industry. Both countries identified the Best value Approach (BVA) as the only solution with documented performance showing it could solve the issues developing countries face with their construction industry. This paper proposes that more research should be performed looking into the ability of the CCI to implement the BVA.

A Research on a Method of Error Separation Based on Wavelet Analysis

2013 ◽  
Vol 380-384 ◽  
pp. 3774-3777
Author(s):  
Gang Yao ◽  
Jian Jun Zhao ◽  
Jing Jie Sun
Keyword(s):  
Wavelet Transform ◽  
Wavelet Analysis ◽  
Systematic Error ◽  
Basic Principle ◽  
Random Error ◽  
Cross Validation ◽  
Immune Algorithm ◽  
Calibration Data ◽  
Analysis Method ◽  
Best Value

According to the error character of the systematic error and random error in calibration data, we put forward using wavelet analysis method to the process of separating error. We give the basic principle and method to dispose random error with Wavelet Analysis. When choosing the threshold, we use GCV(Generalized Cross Validation) principle. Then use IA to search the best value of GCV function and realize the separation simulation of random error in the MATLAB. During the selection operation of IA(Immune Algorithm), the expecting propagation probability is computed in order to guarantee the diversity of the colony and the robustness of algorithm. The results of simulation show that the combination of Wavelet Transform and IA can achieve the aim of separation and have some application prospect in this field.

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