national report of lithuania
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Transition to European Vertical Reference System – EVRS : Status of the geodetic vertical control of Lithuania and further movements. National report of LITHUANIA. Eimuntas Parseliunas Geodetic Institute of Vilnius Technical University e imis @vgtu.lt. - PowerPoint PPT PresentationTRANSCRIPT
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National report of LITHUANIA
THE 4th BALTIC SURVEYORS FORUM , 2013, Ventspils, LATVIA
Eimuntas ParseliunasGeodetic Institute of Vilnius Technical University
Transition to European Vertical Reference System – EVRS:
Status of the geodetic vertical control of Lithuania and further movements
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Outline
•General ideas
•World Geodetic Vertical Datum and System
•Local (European) Vertical Reference System
•National Geodetic Vertical Network
•Further movements
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General ideas
Approaches for the construction and unification of Geodetic Vertical Reference Systems and Frames:
• Spirit leveling • Gravity field
Marker of the vertical reference frame
Physical height difference
Ellipsoidal height difference and geoid
model
Benchmark Precise levelings and gravimetric observations
(leveling approach)
GNSS
(gravity field approach)
Tide gauge Oceanographic model Satellite altimetry
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Ellipsoidal height, orthometric height, local geoid, vertical datum...
General ideas
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General ideas
Geopotential number
Dynamic height
Orthometric height
Nominal value of gravity at mid-latitude
Average value of gravity along the plumb line
Normal height
Average value of normal gravity along the normal plumb line
m2s-2
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General ideas
As there is a similar problem for the uncertainty in the topographic density distribution in determining orthometric heights (but not for normal heights), we conclude that a normal height system is the best choice for a future height system. Once the normal gravity field is defined, the normal heights and the quasigeoid can be determined without any error stemming from the topographic mass distribution, and the quasigeoid can be estimated more precisely than the geoid as the reference surface.
L. E. Sjöberg. The geoid or quasigeoid – which reference surface should be preferred for a national height system? Journal of Geodetic Science, 3(2), 2013, 103-109
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World Geodetic Vertical Datum and System
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World Geodetic Vertical Datum and System
Different teams computed W0 using the same input data, but their own methodologies:
Input data Mean sea surface models (MSS): CLS11 (Schaeffer et al. 2012) DTU10 (Andersen 2010)
Global gravity models (GGM): EGM2008 (Pavlis et al, 2012) EIGEN6C (Förste et al. 2011) GOCO3S (Mayer-Gürr et al. 2012)
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World Geodetic Vertical Datum and SystemSome examples of W0 estimates
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World Geodetic Vertical Datum and System
The reference level W0 for potential differences can arbitrarily be appointed. However, to get the worldwide consistency desired within a global vertical reference system, the selected W0 value must be realisable with high-precision at any time and anywhere around the world.
Therefore, it is necessary to estimate it from real observations of the Earth's gravity field and surface.
The uniqueness, reliability and repeatability of the global reference level W0 (or global geoid) can only be guaranteed by introducing specific conventions (like any other reference system!). On the contrary, there will exist as many height systems as W0 computations.
Remarks on W0
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World Geodetic Vertical Datum and System
All the computations are delivering very close results (around 62 636 854 m2s-2), but there are still differences of about 0,5 m2s-2 (~ 5 cm).
It is necessary to start defining the standards and conventions for a formal recommendation on W0.
Final recommendation (till the end of 2013):
62 636 854,0 +/- 0,2 m2s-2
But...Canada: November 2013, CGVD2013 with 62 636 856,0 m2s-2
USA till 2020 also with 62 636 856,0 m2s-2
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World Geodetic Vertical Datum and System
(EGM96)
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World Geodetic Vertical Datum and System
Project
„Investigations of the requirements for a future 5 mm (quasi)geoid model“
has recently been started within the Nordic Geodetic Commission (NKG).
The NKG gravity database will soon be updated in connection with theNKG-project „Computation of the NKG2014 geoid model“.
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Local (European) Vertical Reference System
Spirit leveling ApproachEVRF2007
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Local (European) Vertical Reference System
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Local (European) Vertical Reference System
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Local (European) Vertical Reference System
Spirit leveling approach Transformation parameter
Estimation of 3 parameters (plane) as transformation parameters between the national
vertical reference frames and EVRF2007
http://www.crs-geo.eu
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Local (European) Vertical Reference System
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Local (European) Vertical Reference System
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Local (European) Vertical Reference System
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Local (European) Vertical Reference System
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Local (European) Vertical Reference System
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Local (European) Vertical Reference System
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National Geodetic Vertical Network (1)
Lithuanian vertical (height) system is still not adopted.
The project of The Resolution of the Government of Lithuania is prepared!
It is based on EVRS Conventions 2007.
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National Geodetic Vertical Network (1)
10 datum points
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National Geodetic Vertical Network (1)
Data of datum points
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National Geodetic Vertical Network (1)
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National Geodetic Vertical Network (3)
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National Geodetic Vertical Network (11)
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National Geodetic Vertical Network (12)
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National Geodetic Vertical Network (13)
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National Geodetic Vertical Network (14)
Differences between some height systems
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National Geodetic Vertical Network (14)
Precise levelling in 2009-2011 (in green) and near future plans (in red)
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Vertical network (1st and 2nd order)
300000 350000 400000 450000 500000 550000 600000 650000
6000000
6050000
6100000
6150000
6200000
6250000
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Vertical network (1st and 2nd order)
Red lines – foreseen 2nd order lines
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Vertical network - numbers
Total lenght of lines – 3100 km:
Ready - 300 km (in 2007) + 300 km (in 2012)
Foreseen – 2200 km (in 2013-2015)
Characteristics of projected 2nd order Network
Total number of points - 3300 (new –2800)
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•Lithuanian state geodetic vertival network fits to the requirements of the modern society
•It necessary to speed up the adoption of the Vertical (height) and Gravity systems in Lithuania
•The densification of the first order vertical network should be executed to fulfill the all needs of the geodesy science
Conclusions
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•Adoption of vertical (height) and gravity systems – 2013
•Quasigeoid model (2 cm) - 2014
•NKG GNSS campaign – 2013
•LitPOS modernization – 2013-2015
•Second order vertical network – 2013-2015
•Absolute gravity measurements at Vilnius, Panevezys and Klaipeda – 2013
•Gravity survey – 2016-2018
•GNSS campaign at vertical network points - 2019
•Quasigeoid model (5mm) - 2020
Future plans
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Thanks…
Thank you for your attention!