KTIMATOLOGIO S.A. M. Gianniou KTIMATOLOGIO S.A. (Hellenic Cadastre) Geodetic Department.

Transcription

1 KTIMATOLOGIO S.A. Realization of ETRS89 in Greece by the HEPOS network M. Gianniou KTIMATOLOGIO S.A. KTIMATOLOGIO S.A. (Hellenic Cadastre) Geodetic Department

2 Outline 1. HEPOS Project 2. Densification project 3. Initial and recent solution 4. Initial solution 5. Recent solution 6. Comparison of initial and recent solution

3 1. HEPOS Project Framework of establishment part of the project Information and Technology Infrastructure for a modern Cadastre a CSF-III project, co-funded by the European Regional Development Fund HEPOS was deployed in 2007, in less than 12 months supports other CSF-III projects, i.e. production of orthophoto maps for whole Greece

4 1. HEPOS Project 98 Reference stations: 87 supporting network- based techniques (VRS - FKP - MAC) 11 for Single- base positioning

5 2. Densification project 113 stations WTZR JOSE GLSV EPN Total 14 GRAZ Class A 13 In the densi- fication zone 3 NOT1 MATE ORID AUT1 NOA1 ANKR TRAB HEPOS Total 99 (98+1) TUC2 NICO RAMO

6 2. Densification project EPN stations 4-char ID Full Name Country Domes No. Network 1 GLSV KIEV UKRAINE 12356M001 EPN class A, IGS 2 JOZE JOZEFOSLAW POLAND 12204M001 EPN class A, IGS 3 MATE MATERA ITALY 12734M008 EPN class A, IGS 4 NICO NICOSIA CYPRUS 14302M001 EPN class A, IGS 5 NOT1 NOTO ITALY 12717M004 EPN class A, IGS 6 TRAB TRABZON TURKEY 20808M001 EPN class B, IGS 7 WTZR BAD KOETZTING GERMANY 14201M010 EPN class A, IGS 8 RAMO MITZPE RAMON ISRAEL 20703S001 EPN class A, IGS 9 ANKR ANKARA TURKEY 20805M002 EPN class A, IGS 10 GRAZ GRAZ AUSTRIA 11001M002 EPN class A, IGS 11 AUT1 THESSALONIKI GREECE 12619M002 EPN class A 12 NOA1 ATHENS GREECE 12620M001 EPN class A 13 TUC2 CHANIA GREECE 12617M003 EPN class A 14 ORID OHRID FYROM 15601M001 EPN class A, IGS

7 2. Densification project HEPOS stations All HEPOS stations are equipped with the same GPS equipment Equipment Model IGS code Receivers Trimble NetRS TRIMBLE NETRS Antennas Trimble Zephyr geodetic TRM Domes Trimble spherical TZGD

8 2. Densification project HEPOS stations All HEPOS antennas are mounted on steel masts On roof of buildings or On side of buildings

9 2. Densification project HEPOS stations All HEPOS antennas are mounted on the frame of the building (reinforced concrete )

10 2. Densification project Observations used 14 days of observations (7-20 October 2007) 3 additional days (17-19 November 2007) to include in the solution station 018B, which replaced station 018A.

11 3. Initial and recent solution Initial solution Computed: December 2007 ETRF2005 (current frame at that time) coordinates used for the HEPOS stations since HEPOS is operable Recent solution Computed: May 2010 Follows the latest EUREF standards, i.e.: Specifications for reference frame fixing in the analysis of a EUREF GPS campaign Ver. 7, 24/10/2008 Guidelines for EUREF Densifications, Ver. 1, 26/05/2009 ETRF2000

12 4. Initial solution Fiducial and validation points 4-char ID Country Network Comments 1 AUT1 GREECE EPN class A fiducial 2 ANKR TURKEY EPN class A, IGS validation point 3 GLSV UKRAINE EPN class A, IGS validation point 4 GRAZ AUSTRIA EPN class A, IGS validation point 5 JOZE POLAND EPN class A, IGS validation point 6 MATE ITALY EPN class A, IGS validation point 7 NICO CYPRUS EPN class A, IGS validation point 8 NOA1 GREECE EPN class A validation point 9 NOT1 ITALY EPN class A, IGS validation point 10 ORID FYROM EPN class A, IGS validation point 11 RAMO ISRAEL EPN class A, IGS validation point 12 TRAB TURKEY EPN class B, IGS validation point 13 TUC2 GREECE EPN class A validation point 14 WTZR GERMANY EPN class A, IGS validation point Note: At the time of computing the HEPOS_initial solution, there was no classification of the EPN stations. The class given in this table refers to the status at the time of writing.

13 4. Initial solution Coordinates of fiducial points Coordinates and velocities used for AUT1 (from EUREF site) ITRF ± ± ± ± ± ± Computed Coordinates for AUT1 (at t c = ) ITRF

14 4. Initial solution Datum definition (ITRF2005) Minimal constraints, i.e. by fixing the coordinates of AUT1. AUT1 is used to compute transformation parameters from ITRF2005 to ETRF2005. For this reason AUT1 is also used for constraining the solution in ITRF2005. An important advantage of AUT1 is that it shows the smallest velocity among the Greek EPN stations and could ensure maximum consistency between HTRS07 and ETRS89 in the northern part of Greece, i.e. on the borders between Greece and the other European countries.

15 4. Initial solution Processing parameters Software used Bernese 5.0 Processing Agency IGN-Spain * * KTIMATOLOGIO S.A. procured the establishment of HEPOS as a turn-key solution including the computation of the station coordinates. This task was assigned by the contractor (Trimble Europe B.V.) to IGN-Spain.

16 4. Initial solution Processing parameters Orbits and ERPs IGS final orbit and ERP information Antenna calibrations stations Absolute antenna phase center corrections based on IGS05 model (exceptions for stations with individual absolute calibrations listed in epnc_05.atx) considering antenna radome codes. Antenna calibrations satellites Absolute antenna phase centre corrections based on IGS05 model calibrations

17 4. Initial solution Processing parameters Preprocessing Phase preprocessing in a baseline by baseline mode using triple differences. In most cases cycle slips are fixed looking simultaneously at different linear combinations of L1 and L2. If a cycle slip cannot be fixed reliably, bad data points are removed or new ambiguities are set up. Basic Observable Carrier phase, code only used for receiver clock synchronization.

18 4. Initial solution Processing parameters Elevation angle cutoff 3 degrees + elevation dependent weighting with cos-z Data sampling For ambiguity resolution: 30 s. For final processing: 180 s. Modeled observable Double-differences, ionosphere-free linear combination.

19 4. Initial solution Processing parameters Troposphere Dry-Niell as a priori model, estimation of zenith delay corrections at 1hour intervals for each station, using the wet-niell MF, no a priori sigmas. Horizontal gradient parameter estimated/day/station (TILTING), no a priori constraints. Compute daily TRO files with fixed cumulative. Coordinates input from weekly solution. Ionosphere Regional ionospheric model calculated. Only used for QIF ambiguity resolution. Not modeled in final solution (ionosphere eliminated by forming the ionosphere-free linear combination of L1 and L2).

20 4. Initial solution Estimated parameters Adjustment Weighted least-squares algorithms. Rejection Criteria Daily RINEX observation files containing less than 10 percent of possible observation are ignored. The threshold value concerning data screening is 2.5 mm, specifically for a normalized, or L1 zero difference zenith residual. Station where baseline data exceeding the overall sigma level of 5 millimeters is excluded.

21 4. Initial solution Estimated parameters Troposphere Absolute constraints: 5.0 m, Relative constraints: 5.0 m. Ionosphere Regional ionospheric model for QIF ambiguity resolution. Ambiguity resolution Ambiguity resolution is performed by using the quasi-ionosphere-free (QIF) strategy with regional TEC information. Elevation angle cutoff: 10 degrees.

22 4. Initial solution Estimated parameters Satellite clock bias Satellite clock biases are not estimated but eliminated by forming doubledifferences. Receiver clock bias Receiver clock corrections are estimated as part of the biases preprocessing using code measurements. They are finally eliminated by forming double differences.

23 4. Initial solution Estimated parameters Planetary Ephemeris DE200 Tidal effects Solid earth tidal displacements are modeled according to IERS conventions Ocean loading Using model computed by H.G.Scherneck Onsala Space Observatory FES2004 model for each station. Atmospheric loading No atmospheric loading corrections are taken into account.

24 4. Initial solution Repeatabilities (North) repeatabilities N (mm) ANKR MATE RAMO 002A 007A 012A 017A 021A 026A 031A 036A 041A 046A 051A 056A 061A 066A 071A 076A 081A 086A 091A 096A

25 4. Initial solution Repeatabilities (East) repeatablities E (mm) ANKR MATE RAMO 002A 007A 012A 017A 021A 026A 031A 036A 041A 046A 051A 056A 061A 066A 071A 076A 081A 086A 091A 096A

26 4. Initial solution Repeatabilities (Up) repeatabilities U (mm) ANKR MATE RAM 002A 007A 012A 017A 021A 026A 031A 036A 041A 046A 051A 056A 061A 066A 071A 076A 081A 086A 091A 096A

27 4. Initial solution Comparison of ITRF2005/ coordinates: initial solution vs. EUREF solution (EPN_A_ITRF2005_C1570) In XYZ Stn DX (mm) DY (mm) DZ (mm) ANKR AUT GLSV GRAZ JOZE MATE NICO NOA NOT ORID RAMO TUC WTZR In NEU Stn North (mm) East (mm) Up (mm) ANKR AUT GLSV GRAZ JOZE MATE NICO NOA NOT ORID RAMO TUC WTZR

28 4. Initial solution Transformation to ETRS89 At the time realization of HTRS07, version 6 of the B/A memo was valid.

29 4. Initial solution Transformation to ETRS89 At the time of realization of HTRS07, no velocities were available for the HEPOS stations. Furthermore, the velocity field in Greece is complex and inhomogeneous. The velocities of the Greek stations differ strongly among each other. Any application of individual velocities would distort the homogeneity of the HEPOS network. For these reasons, no transformation t o t = was done. Note: According to the current version of the B/A memo (version 7) it is no longer recommended to propagate the station coordinates by means of whatever intra plate velocities to other epoch than the central epoch t c of the used

30 4. Initial solution Transformation to ETRS89 Use EUREF coordinates and velocities to compute ECEF coordinates of AUT1 in: - ITRF05/ (central epoch for HEPOS network adjustment) - ETRF05/ (central epoch of the HEPOS GPS campaign for the computation of transformation model) Compute the translation components Χ, Υ and Ζ between the above ECEF coordinates of AUT1 Use of the above translation parameters to transform all HEPOS stations from ITRF05/ to ETRF05/

31 4. Initial solution Transformation to ETRS89 Coordinates and velocities used for AUT 1 (from EUREF site) ITRF ± ± ± ± ± ± ETRF ± ± ± ± ± ± Resulting coordinates for AUT1 and transformation parameters ITRF2005/ ETRF2005/ Translation parameters from ITRF2005/ to ETRF2005/ * X = X = DX = Y = Y = DY = Z = Z = DZ = * Epoch was chosen, as it was the central epoch of the national GPS campaign carried-out for the computation of a transformation model between HTRS07 and the National coordinate system HGRS87

32 5. Recent solution Fiducial points 4-char ID Country Network Comment 1 AUT1 GREECE EPN class A In the densification zone 2 ANKR TURKEY EPN class A, IGS 3 GLSV UKRAINE EPN class A, IGS 4 GRAZ AUSTRIA EPN class A, IGS 5 JOZE POLAND EPN class A, IGS 6 MATE ITALY EPN class A, IGS 7 NICO CYPRUS EPN class A, IGS 8 NOT1 ITALY EPN class A, IGS 9 NOA1 GREECE EPN class A In the densification zone 10 ORID FYROM EPN class A, IGS 11 RAMO ISRAEL EPN class A, IGS 12 TUC2 GREECE EPN class A In the densification zone 13 WTZR GERMANY EPN class A, IGS

33 5. Recent solution Coordinates of fiducial points The ITRF2005/ coordinates of the fiducial points were computed using solution C1570. Stn Coordinates and velocities at to = (EPN_A_ITRF2005_C1570) Computed coordinates at tc = Data Start - Data End DOY/year - DOY/year X Y Z Vx Vy Vz X Y Z ANKR 309/ / AUT1 309/ / GLSV 309/ / GRAZ 309/ / JOZE 309/ / MATE 309/ / NICO 077/ / NOA1 309/ / NOT1 309/ / ORID 212/ / RAMO 309/ / TRAB 345/ /2007 n/a n/a n/a n/a n/a n/a TUC2 309/ / WTZR 309/ /

34 5. Recent solution Datum definition (ITRF2005) Using minimal constraints, to compute three translation parameters on the network s barycentre. This strategy has the advantage that small errors in the coordinates do neither distort the network geometry nor significantly degrade the datum definition per se.

35 5. Recent solution Processing parameters The processing parameters and the repeatabilities are the same like in the Initial solution.

36 5. Recent solution Comparison of ITRF2005/ coordinates: recent solution vs. EUREF solution (EPN_A_ITRF2005_C1570) In XYZ Stn DX (mm) DY (mm) DZ (mm) ANKR AUT GLSV GRAZ JOZE MATE NICO NOT NOA ORID RAMO TUC WTZR In NEU Stn North (mm) East (mm) Up (mm) ANKR AUT GLSV GRAZ JOZE MATE NICO NOT NOA ORID RAMO TUC WTZR

37 5. Recent solution Transformation to ETRS89 The transformation of the ITRF2005/ coordinates to ETRF2000/ was done using the EPN web page tool.

38 6. Comparison of initial and recent solution Comparison of ETRS89 coordinates: Initial solution vs. recent solution D North (mm) A 006A 011A 016A 020A 025A 030A 035A 040A 045A 050A 055A 060A 065A 070A 075A 080A 085A 090A 095A

39 6. Comparison of initial and recent solution Comparison of ETRS89 coordinates: Initial solution vs. recent solution D East (mm) A 006A 011A 016A 020A 025A 030A 035A 040A 045A 050A 055A 060A 065A 070A 075A 080A 085A 090A 095A

40 6. Comparison of initial and recent solution Comparison of ETRS89 coordinates: Initial solution vs. recent solution D Up (mm) A 006A 011A 016A 020A 025A 030A 035A 040A 045A 050A 055A 060A 065A 070A 075A 080A 085A 090A 095A

41 6. Comparison of initial and recent solution Comparison of ETRS89 coordinates: Initial solution vs. recent solution Statistics DN (mm) DE (mm) DS (mm) DU (mm) Max D Mean D Mean D Conclusion: The two solutions are consistent to a few centimeters: Maximum differences do not exceed 3 cm (horizontal) and 4 cm (vertical). Mean differences are below 2 cm both in the horizontal and in the vertical component.

42 Acknowledgments IGN-Spain for the computation of the HEPOS network. Prof. K. Katsampalos and C. Kotsakis (AUTH: Aristotle University of Thessaloniki) for assisting KTIMATOLOGIO SA in the definition HTRS07 and the computation of coordinate transformation model. The chair and the members of EUREF-TWG for their valuable comments in the preparation of the report. The HEPOS project is part of the Operational Program Information Society and is co-funded by the European Regional Development Fund.