Local Quasi-Geoid Refinement Based on Spherical Cap Harmonic Model

2012 ◽  
Vol 226-228 ◽  
pp. 1947-1950 ◽  
Author(s):  
Jin Yun Guo ◽  
Shu Yang Wang ◽  
Guo Wei Li ◽  
Wei Hua Mao ◽  
Yuan Ming Ji
Keyword(s):  
Height Anomaly ◽  
Practical Case ◽  
Harmonic Model ◽  
Geoid Model ◽  
Normal Height ◽  
Spherical Cap ◽  
Geodetic Height ◽  
Gps Leveling ◽  
Spherical Cap Harmonic Model ◽  
Selection Of

The local quasi-geoid model up to centimeter precision has became the basic requirement for the development of modern surveying and mapping science. There are a variety of models can be used for the quasi-geoid refinement, including the spherical cap harmonic model (SCH). This paper studies the theory of SCH to get the spherical cap harmonic expression to fit the height anomaly in the least squares sense, which is to achieve the transformation between the geodetic height and the normal height. We also discuss the selection of the maximum model degree in local region. The practical case is studied to refine the local quasi-geoid model with SCH using GPS/leveling data at 85 points. The results indicate that the local quasi-geoid model can reach 3 centimeter-level at the internal and external fitting precision.

scholarly journals A Spherical Cap Harmonic Model of the Satellite Magnetic Anomaly Field Over China and Adjacent Areas.

1992 ◽  
Vol 44 (3) ◽  
pp. 243-252 ◽  
Author(s):  
Zhen-chang AN ◽  
Shi-zhuang MA ◽  
Dong-hai TAN ◽  
D. R. BARRACLOUGH ◽  
D. J. KERRIDGE
Keyword(s):  
Magnetic Anomaly ◽  
Harmonic Model ◽  
Spherical Cap ◽  
Anomaly Field ◽  
Spherical Cap Harmonic Model

Application of Artificial Neural Network in GPS Height Transformation

2014 ◽  
Vol 501-504 ◽  
pp. 2162-2165 ◽  
Author(s):  
Bo Fu ◽  
Xiang Liu
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Nonlinear Coefficient ◽  
Height Anomaly ◽  
Engineering Practice ◽  
Model Structure ◽  
Normal Height ◽  
Sample Data ◽  
Geodetic Height ◽  
Residual Errors

GPS technology has been widely used since it was put into use. At present, the plane locational accuracy of GPS can already achieve millimeter level. But in terms of height, in order to apply the GPS ellipsoidal height in engineering practice, the geoid seperation or height anomaly of the corresponding point must be achieved to transform GPS geodetic height to normal height. In this paper, by taking 12 points from the national GPS control network of Xuxiang Village of Haining City as sample data, a BP neural network using 3-4-2-1 model structure is adopted and a nonlinear coefficient 1.1 is added in the response function. The height anomalies of the 5 points of the test set are calculated and the residual errors are achieved by comparing with the measured values. The internal and external coincidence accuracies of the model are 0.824cm and 0.922cm separately. The result shows that the model can completely meet the precision requirement of the fourth-grade leveling survey and can be used to transform the heights of the study area.

Spherical cap harmonic model for mapping and predicting regional TEC

GPS Solutions ◽  
2010 ◽  
Vol 15 (2) ◽  
pp. 109-119 ◽  
Author(s):  
Jingbin Liu ◽  
Ruizhi Chen ◽  
Zemin Wang ◽  
Hongping Zhang
Keyword(s):  
Harmonic Model ◽  
Spherical Cap ◽  
Spherical Cap Harmonic Model

scholarly journals THE GEOID AND QUASIGEOID OF SÃO PAULO STATE USING THE UPDATED GRAVIMETRIC DATA AND THE 2018 BVRF

2021 ◽  
Vol 27 (2) ◽  
Author(s):  
Valéria Cristina Silva ◽  
Flavio Guilherme Vaz de Almeida Filho ◽  
Denizar Blitzkow ◽  
Ana Cristina Oliveira Cancoro de Matos
Keyword(s):  
Gravity Anomalies ◽  
Geoid Height ◽  
Sao Paulo ◽  
Height Anomaly ◽  
São Paulo ◽  
Geoid Model ◽  
Normal Height ◽  
Paulo State ◽  
Gravimetric Data ◽  
São Paulo State

Abstract The combination of physical and geometric heights, required for geodetic purposes, uses Global Geopotential Models (GGMs), local geoid, or quasigeoid models. The geoid height and the height anomaly, provided by GGMs, are not accurate enough for most engineering applications. Considering the normal height system of Brazil and the physical concepts of the involved reference surfaces, a quasigeoid model is more appropriate than the current Brazilian geoid model MAPGEO2015. This paper shows the determination of the geoid and the quasigeoid models for São Paulo state using the updated gravimetric data and the new system of the normal height of the 2018 Brazilian Vertical Reference Frame (BVRF). The computation of the quasigeoid model was performed by numerical integration through the Fast Fourier Transform (FFT). The Molodensky gravity anomaly was determined in a 5’ grid and reduced and restored using the Residual Terrain Model (RTM) technique and the XGM2019e GGM truncated at degree and order 250 and 720. The geoid model was derived from the Bouguer gravity anomalies. The quasigeoid model validation has shown a Root Mean Square (RMS) difference of 18 cm compared with the Global Positioning System (GPS) measurements in the levelling network.

scholarly journals DETERMINATION OF GEOGRAPHIC POSITION OF OBJECT BY APPLYING 3D POLAR OBSERVATIONS

Aviation ◽  
2010 ◽  
Vol 14 (2) ◽  
pp. 43-48 ◽  
Author(s):  
Algimantas Zakarevičius ◽  
Vladislovas Česlovas Aksamitauskas ◽  
Algimantas Jakučionis ◽  
Arminas Stanionis
Keyword(s):  
Digital Terrain Model ◽  
Geoid Model ◽  
Normal Height ◽  
Cartesian Coordinates ◽  
Object A ◽  
Terrain Model ◽  
The Earth ◽  
Geographic Position ◽  
Geodetic Height ◽  
Airport Runway

The geographic position of an object is determined by geodetic latitude, geodetic longitude, geodetic and normal height, and height of the object above the surface of the earth. To determine the geographic position of an object, a technologic scheme is recommended: by applying 3D polar observations, the 3D Cartesian coordinates of the object in the local horizontal coordinate system (for example, with an airport runway tied system) are determined; local horizontal 3D Cartesian coordinates are recomputed into the system of geocentric equatorial 3D Cartesian coordinates; the geodetic coordinates (geodetic latitude, geodetic longitude, and geodetic height) are computed from the geocentric equatorial 3D Cartesian coordinates; based on information about geodetic height and the digital geoid model, the normal height of the object is computed; and object height above the earth is computed from normal height and the digital terrain model. Algorithms for the realisation of this technologic scheme are presented. Santrauka Objekto geografine padetis apibūdinama geodezine platuma, geodezine ilguma, geodeziniu bei normaliniu aukščiais ir objekto aukščiu virš Žemes paviršiaus. Objekto geografinei padečiai nustatyti rekomenduojama tokia technologine schema: taikant erdvinius polinius matavimus, nustatomos objekto erdvines stačiakampes koordinates vietineje (pvz., oro uosto) horizontineje koordinačiu sistemoje; vietines horizontines erdvines stačiakampes koordinates perskaičiuojamos i geocentriniu ekvatoriniu erdviniu stačiakampiu koordinačiu sistema; pagal geocentrines ekvatorines erdvines stačiakampes koordinates apskaičiuojamos geodezines koordinates (geodezine platuma, geodezine ilguma ir geodezinis aukštis); žinant geodezini aukšti ir turint skaitmenini geoido modeli, skaičiuojamas objekto normalinis aukštis; turint normalini aukšti ir skaitmenini reljefo modeli, apskaičiuojamas objekto aukštis virš Žemes paviršiaus. Pateikiami algoritmai šiai technologinei schemai realizuoti.

Ultrasound screening and catamnesis of euploid fetuses with nasal bones aplasia/hypoplasia

2017 ◽  
Author(s):  
N.P. Veropotvelyan, A.A. Bondarenko
Keyword(s):  
Chromosomal Abnormalities ◽  
Nasal Bone ◽  
Normal Karyotype ◽  
Psychomotor Development ◽  
Ultrasound Screening ◽  
Normal Height ◽  
Term Infants ◽  
Nasal Bones ◽  
Postnatal Outcome ◽  
Selection Of

Objective. To evaluate the pre- and postnatal outcomes of euploid fetuses with aplasia/hypoplasia of the nasal bones (NB). Methods. We have made the catamnestic monitoring of children with a normal karyotype, who had been prenatally detected NB aplasia or hypoplasia (less than 5 perentile) at 11–24 weeks of gestation at ultrasound screening in the period between 2006–2015 years. Our study included a selection of 242 fetuses with NB aplasia or hypoplasia, in 128 (52.8 %) of them the NB was not visualized or appeared as an echogenic dot only. Results. Among all 63 fetuses with NB aplasia (absence or looks as an echogenic dot) in the 1st trimester in 24 (38 %) cases chromosomal abnormalities (CA) were found (including T21 — 15 (62.5 %) cases). Other 39 (61.9 %) fetuses had a normal karyotype. Among 65 fetuses with NB aplasia, examined in the 2nd trimester of gestation 12 (18.4 %) cases of CA were detected (one fetus with T21 had the only one ultrasound marker – isolated NB aplasia), 53 (81.5 %) fetuses had a normal karyotype. 62 mothers of the euploid fetuses with NB aplasia had been surveyed. We have received and analyzed 31 (50 %) responses. In 16 cases of euploid fetuses with NB, aplasia pregnancy outcome was adverse or relatively unfavorable, only 5 (31.2 %) fetuses of them had isolated NB aplasia. In other cases healthy full-term infants were born, who showed normal height and weight indexes, physical and psychomotor development observed in age from 0 to 10. Conclusion. In 51.6 % fetuses and children prenatally had aplasia of the nasal bone was marked by unfavorable pre- or postnatal outcome, according to the survey of their mothers.

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