scholarly journals A conventional approach for comparing vertical reference frames

2012 ◽  
Vol 2 (4) ◽  
pp. 319-324
Author(s):  
C. Kotsakis
Keyword(s):  
Reference Frames ◽  
Optimal Estimation ◽  
Transformation Model ◽  
Practical Implementation ◽  
Height Determination ◽  
Vertical Datum ◽  
Key Issues ◽  
Perturbation Parameters ◽  
Physical Height ◽  
Vertical Positioning

AbstractA conventional transformation model between different realizations of a vertical reference system is an important tool for geodetic studies related to precise vertical positioning and physical height determination. Its fundamental role is the evaluation of the consistency for colocated vertical reference frames that are obtained from different observation techniques, data sources or optimal estimation strategies in terms of an appropriate set of “vertical datum perturbation” parameters. Our scope herein is to discuss a number of key issues related to the formulation of such a transformation model and to present some simple examples from its practical implementation in the comparison of existing vertical frames over Europe.

scholarly journals Towards a vertical datum standardisation under the umbrella of Global Geodetic Observing System

2012 ◽  
Vol 2 (4) ◽  
pp. 325-342 ◽  
Author(s):  
L. Sánchez
Keyword(s):  
Gravity Field ◽  
Reference Frames ◽  
International Association ◽  
Surface Geometry ◽  
Field Service ◽  
Height Determination ◽  
Satellite Positioning ◽  
Starting Point ◽  
Vertical Datum ◽  
Physical Height

AbstractMost of the existing height systems refer to local sea surface levels, are stationary (do not consider variations in time), and realise different physical height types (orthometric, normal, normal-orthometric, etc.). In general, their accuracy is about two orders of magnitude less than that of the realisation of geometric reference systems (sub millimetre level). The Global Geodetic Observing System (GGOS) of the International Association of Geodesy (IAG), taking care of providing a precise geodetic infrastructure for monitoring the system Earth, promotes the standardisation of height systems worldwide. The main objectives are: (1) to provide a reliable frame for consistent analysis and modelling of global phenomena and processes affecting the Earth’s gravity field and the Earth’s surface geometry; and (2) to support the precise combination of physical and geometric heights in order to exploit at a maximum the advantages of satellite geodesy (e.g. combination of satellite positioning and gravity field models for worldwide unified precise height determination). According to this, the GGOS Theme 1 ”Unified Height System” was established in February 2010 with the purpose to bring together existing initiatives and to address the activities to be faced. Starting point are the results delivered by the IAG Inter-Commission Project 1.2 ”Vertical Reference Frames” during the period 2003-2011. The present actions related to the vertical datum homogenisation are being coordinated by the working group ”Vertical Datum Standardisation”, which directly depends on the GGOS Theme 1 and is supported by the IAG Commissions 1 (Reference Frames) and 2 (Gravity Field), as well as by the International Gravity Field Service (IGFS). This paper discusses some aspects to take into consideration for the realisation of a standardised globally unified vertical reference system.

scholarly journals Perspectives on Larval Behaviour in Biophysical Modelling of Larval Dispersal in Marine, Demersal Fishes

Oceans ◽  
2020 ◽  
Vol 2 (1) ◽  
pp. 1-25
Author(s):  
Jeffrey M. Leis
Keyword(s):  
Fish Larvae ◽  
Behavioural Change ◽  
Larval Fishes ◽  
Larval Behaviour ◽  
Key Issues ◽  
Modelling Effort ◽  
Validation Research ◽  
Vertical Positioning ◽  
Study Species ◽  
Demersal Fishes

Biophysical dispersal models for marine fish larvae are widely used by marine ecologists and managers of fisheries and marine protected areas to predict movement of larval fishes during their pelagic larval duration (PLD). Over the past 25 years, it has become obvious that behaviour—primarily vertical positioning, horizontal swimming and orientation—of larvae during their PLD can strongly influence dispersal outcomes. Yet, most published models do not include even one of these behaviours, and only a tiny fraction include all three. Furthermore, there is no clarity on how behaviours should be incorporated into models, nor on how to obtain the quantitative, empirical data needed to parameterize models. The PLD is a period of morphological, physiological and behavioural change, which presents challenges for modelling. The present paper aims to encourage the inclusion of larval behaviour in biophysical dispersal models for larvae of marine demersal fishes by providing practical suggestions, advice and insights about obtaining and incorporating behaviour of larval fishes into such models based on experience. Key issues are features of different behavioural metrics, incorporation of ontogenetic, temporal, spatial and among-individual variation, and model validation. Research on behaviour of larvae of study species should be part of any modelling effort.

On perfecting the employment of GSK-2011 reference frame in the Far East territory

2019 ◽  
Vol 951 (9) ◽  
pp. 2-9
Author(s):  
N.A. Bovshin
Keyword(s):  
Reference Frame ◽  
Russian Federation ◽  
Reference Frames ◽  
Far East ◽  
Angular Motion ◽  
Transformation Model ◽  
The Far East ◽  
The Russian Federation ◽  
Regional Transformation

ITRFs and ITRF like reference frames have a drawback that limits or makes its wide use difficult while surveying in the Russian Federation. These are significant velocities of changing geodetic stations’ coordinates throughout the entire territory. It leads to necessity of reducing reference geodetic stations and survey points positions from reference epoch to observation ones and vice versa. To avoid this necessity for the most of surveys in the Russian Federation territory, a transformation model [1] of relative behaviour of GSK-2011 and ITRF-2014 reference frames was created. Unfortunately, the model does not work properly in the Far East. That is why in this paper a new, regional transformation model that represent relative behaviour of GSK-2011 and ITRF-2014 reference frames in the territory was described. As it was shown in the paper, the result is equivalent to setting a new, auxiliary version of GSK-2011 reference frame in the Far East territory – GSK-2011-FE, that has no drawbacks of ITRF-like systems. Both frames coincide with each other at the reference epoch t0 and relate by a transformation of angular motion at an epoch t.

Motion Model Parameters Estimation for Electronic Image Stabilization Instrument

2013 ◽  
Vol 325-326 ◽  
pp. 1543-1546
Author(s):  
Xun Yu Zhong ◽  
Tian Hui Ren
Keyword(s):  
Motion Estimation ◽  
Least Squares Method ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Block Matching ◽  
Parameters Estimation ◽  
Transformation Model ◽  
Image Motion ◽  
Model Parameters ◽  
Image Stabilization

Fast and optimal motion estimation method is proposed for electronic image stabilization. First, an approach for macro-block judgment is presented. Before motion vectors calculation, gradient information is analyzed, only useful reference blocks that are indispensable for accurate motion estimation are selected, by which the number of macro-blocks for subsequent calculation is reduced. Second, in the block matching, an improved SSDA is used to reduce computing cost. Finally, the affine transformation model and similarity transformation model of image motion are created and using least squares method for solving the optimal estimation of model parameters. Experimental results show the accuracy and fast computing speed of the proposed method.

scholarly journals Absolute Performance of AUSGeoid09 in Mountainous Regions

2014 ◽  
Vol 8 (3) ◽  
Author(s):  
Vittorio Sussanna ◽  
Volker Janssen ◽  
Peter Gibbings
Keyword(s):  
Single Point ◽  
Satellite System ◽  
Substantial Improvement ◽  
Mountainous Regions ◽  
Absolute Sense ◽  
Sea Surface Topography ◽  
Height Determination ◽  
South Wales ◽  
Vertical Datum ◽  
Height Datum

AbstractThe Australian Height Datum (AHD) is the current national vertical datum for Australia, and AUSGeoid09 is the latest quasigeoid model used to compute (normal-orthometric)AHDheights fromGlobalNavigation Satellite System (GNSS) derived ellipsoidal heights. While previous studies have evaluated the AUSGeoid09 model across Australia, such studies have not focused on mountainous regions in particular. This paper investigates the performance of AUSGeoid09 in an absolute sense in the Mid Hunter and Snowy Mountains regions of New South Wales. Absolute (i.e. single point) comparisons were undertaken between AUSGeoid09-derived heights and published AHD heights. The performance of AUSGeoid09 was evaluated relative to its predecessor AUSGeoid98. In both study areas, an overall improvement is evident when applying AUSGeoid09 to compute AHD heights in an absolute sense. In the MidHunter, AUSGeoid09 provided a substantial improvement over its predecessor, clearly demonstrating the benefits of its new geometric component on GNSS-derived AHD height determination. In the Snowy Mountains, moderate improvement over AUSGeoid98 was evident. However, a slope was detected for AUSGeoid09 residuals, and it appears that the geometric component may have overcompensated for sea surface topography in this area. While this appraisal of AUSGeoid09 performance in mountainous regions is encouraging, it has been shown that some discrepancies still remain between AUSGeoid09-derived heights and AHD. Eventually, a new vertical datum will be necessary to ensure homogeneity across Australia.

scholarly journals The Influence of Application a Simplified Transformation Model Between Reference Frames ECEF and ECI onto Prediction Accuracy of Position and Velocity of GLONASS Satellites

2015 ◽  
Vol 99 (1) ◽  
pp. 19-27 ◽  
Author(s):  
Robert Krzyżek ◽  
Bogdan Skorupa
Keyword(s):  
State Vector ◽  
Prediction Accuracy ◽  
Reference Frames ◽  
Satellite Geodesy ◽  
Transformation Model ◽  
Transformation Models ◽  
Short Term ◽  
Broadcast Ephemeris ◽  
Comparison Of The Results

Abstract In computational tasks of satellite geodesy there is a need for transformation of coordinates between reference frames ECEF – Earth Centered, Earth Fixed and ECI – Earth Centered, Inertial. Strict and simplified transformation models, which can be used in case of the position and velocity short-term predictions of GLONASS satellites, have been presented in this study. Comparison of the results of state vector components predictions of the GLONASS satellites, in dependence of the used transformation model, have also been presented. Accuracy of the prediction has been determined on the basis of the analyse of deviations of the predicted positions and velocities of GLONASS satellites from their values given in broadcast ephemeris.

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.

Model Parameters Estimation for Image Motion Compensation

2013 ◽  
Vol 347-350 ◽  
pp. 3672-3676
Author(s):  
Xun Yu Zhong ◽  
Xiao Shan Li ◽  
Yong Gang Zhao
Keyword(s):  
Motion Estimation ◽  
Least Squares Method ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Block Matching ◽  
Parameters Estimation ◽  
Transformation Model ◽  
Image Motion ◽  
Model Parameters ◽  
Macro Block

Fast and optimal motion estimation method is proposed for electronic image stabilization. First, an approach for macro-block judgment is presented. Before motion vectors calculation, gradient information is analyzed, only useful reference blocks that are indispensable for accurate motion estimation are selected, by which the number of macro-blocks for subsequent calculation is reduced. Second, in the block matching, an improved SSDA is used to reduce computing cost. Finally, the affine transformation model and similarity transformation model of image motion are created and using least squares method for solving the optimal estimation of model parameters. Experimental results show the accuracy and fast computing speed of the proposed method.

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