Revision of geocentric datum of malaysia (gdm2000) Dr Azhari bin Mohamed, Hasan bin Jamil, David Chang Leng Hua, Muhammad Asyran bin Che Mat Geodesy Section, Mapping Division, Department of Survey and Mapping Malaysia (JUPEM)
INTRODUCTION !
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The Department of Survey and Mapping Malaysia (JUPEM (JUPEM)) - the authorize authorize agency in the maintaining of the national reference system for for horizo horizontal ntal and vertical control control in Malaysia. The Geocentric Datum of Malaysia or GDM2000 GDM 2000 is the new nation national al geodetic datum for Malaysia Malaysia and it replaces the old datum datum of MRT48 MR T48 and BT68. It was off officially icially launched nationwide nation wide on 26 Aug August ust 2003.
INTRODUCTION !
!
The Department of Survey and Mapping Malaysia (JUPEM (JUPEM)) - the authorize authorize agency in the maintaining of the national reference system for for horizo horizontal ntal and vertical control control in Malaysia. The Geocentric Datum of Malaysia or GDM2000 GDM 2000 is the new nation national al geodetic datum for Malaysia Malaysia and it replaces the old datum datum of MRT48 MR T48 and BT68. It was off officially icially launched nationwide nation wide on 26 Aug August ust 2003.
Tectonic Plates
Our Dynamic Earth
Tectonic Plate Motions
3cm/y r
MASS Station Estimated Velocities (1999 – 2002)
Launching of GDM2000
FIRST REALISATION OF GDM2000 !
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MASS Stations - Zero Order Geodetic Network Basis for the realization of the precise geocentric datum in ITRF2000 17 MASS Stations and 11 IGS Stations were used in the computation
ZERO ORDER GEODETIC NETWORK !
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MASS Stations – Zero Order Geodetic Network Basis for the realization of the precise geocentric datum in ITRF2000 17 MASS Stations and 11 IGS Stations were used in the computation
MASS
DATA ACQUISITION IGS STATIONS
SHAO
LHAS KUNM
WUHN
PIMO
IIS C
NTUS
BAKO
COCO KARR
GUAM
DATA PROCESSING !
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Software: Bernese GPS processing software version 4.2 Automated by using Bernese Processing Engine (BPE) that ran on Red Hat Linux version 6.2 Processing Steps: Pre-Processing, Daily Adjustment and Weekly Combination
FINAL COMBINED SOLUTION !
Two strategies were employed to obtain an optimum results and to check for outliers in the final adjustment. The two strategies were as follow: - Free Network with introduction of Helmert Transformation - Heavily constrained adjustment
FREE NETWORK ADJUSTMENT RMS of Residuals 14 12 10 North 8 East
m m
6 Up 4 2 0 Arau
Geti
Kual
Utm j
Ktpk
Statio n
Ipoh
Usm p
Kuan
FREE NETWORK ADJUSTMENT !
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Final coordinates - transformed to mid of observation epoch using 11 IGS Stations Internal accuracy of the MASS stations - 5 to 11 mm in the horizontal component - 5 to 12 mm in the height component Comparison of IGS stations coordinates
FREE NETWORK ADJUSTMENT !
The accuracy for MASS stations with respect to the ITRF2000 reference frame with free network strategy is 9 to 15 mm in the horizontal component and 12 to 19 mm in height
HEAVILY CONSTRAINED ADJUSTMENT
mm
RMS of Residuals
1 8 1 6 1 4 1 2 1 0
North
Series 1 East Series
2
8
Series 3
Up
6 4 2 0 Arau
Get i
Kua l
Utm j Statio
Ktp k
Ipo h
Usmp
Kua n
HEAVILY CONSTRAINED ADJUSTMENT !
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The heavily constrained adjustment was to adopt the specific reference frame in ITRF2000 The accuracy of station coordinates is between 3 to 16 mm in horizontal component and 8 to 13 mm for the height
GDM2000 !
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High Quality Coordinates of MASS Stations The Zero Order Geodetic Network is now defined on ITRF2000 reference frame to within 2 cm accuracy with final coordinates in ITRF2000 at Epoch 1 January 2000 Known as Geocentric Datum of Malaysia (GDM2000) – officially adopted on 26 August 2003
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MALAYSIAN PRIMARY GEODETIC NETWORK 2000 (MPGN2000) Strengthening of PMGSN94 AND EMGSN97 - 36 stations (PMGSN94) and 30 stations (emgsn97) re-observed - The aim was to connect the existing PMGSN94 and EMGSN97 to the Zero Order Geodetic Network
Strengthening of PMSN 7
ARAU P29 9 P29 8
GET I
P29 7
6
P23 8
P31 0
USMP
KUAL
P28 1
5
P24 4
P24 7
P29 0
P27 4 P21 3
P10 2
P22 1
P26 3
P22 9 P25 5
P21 9
P25 8
IPOH GP2 8
GP0 2
4
GP3 2
KUAN
GP2 4
GP0 6
KTPK
GP3 6
GP3 7
GP2 1 GP9 8
3 GP1 8
GP4 3 GP4 7 M33 1
2
Mass Station Main Station
GP5 8 GP5 4
GP8 4 GP5 0
UTMJ GP5 2
Existing PMSN
MPGN2000 !
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Heavily contrained adjustment with MASS stations held fixed. The adjustment of the MPGN2000 achieved an accuracy of 3 cm refered to ITRF2000 Epoch 1 January 2000
MPGN2000
MyRTKnet !
Beginning 2002, JUPEM has established a network known as the Malaysia Real-Time Kinematic GNSS Network or MyRTKnet that uses a new generation of RTK solution known as Virtual Reference Station (VRS). MyRTKnet is based on a network of continuous operating GPS reference stations.
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By 2008, Malaysia has seventy-eight (78) RTK reference stations for the network covering the whole Peninsular Malaysia with fifty (50) stations, Sabah (14 stations) and Sarawak (14 stations).
MyRTKnet
3 Earthquakes
Acheh, 26 Dec 04 9.2 Richter Scale
Nias, 28 Mar 05 8.7 Richter Scale Bengkulu, 12 Sep 07 7.9 Richter Scale
2004 Earthquake
1.5 to 17 cm
2005 Earthquake
1.0 to 6.5 cm
2007 Earthquake
1.0 to 3 cm
POST-SEISMIC MOTION 2006
POST-SEISMIC MOTION 2007
POST-SEISMIC MOTION 2008
2004 - 2009 DISPLACEMENT
1.0 to 25.8 cm
MyRTKnet IN GDM2000 (2009) !
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GPS data from seventy-eight (78) MyRTKnet stations and fifty-six (56) IGS stations in ITRF2005 for the years 2006 to 2009 were used in the data processing to re-establish the zero order geodetic network. The combined adjustment for these data was fixed at epoch 1 January 2000. The coordinates was named as
[email protected] (2009).
MyRTKnet IN GDM2000 (2009) !
Comparison with the original
[email protected] coordinates was carried out by using three parameter Helmert transformation process. The RMS fitting for the coordinates of four (4) reference stations (KUCH, BINT, KINA & MIRI)were less than one (1) cm in the north, east and height component.
MyRTKnet IN GDM2000 (2009) !
The final combined adjustment used the original GDM2000 reference frame as the reference by holding the coordinates of six (6) stations fixed. With this adjustment, the resulting coordinates of the MyRTKnet stations were obtained and are labelled as GDM2000 (2009)
MPGN2000 (2009) !
Apart from producing MyRTKnet stations in GDM2000 (2009) coordinates, similar efforts were also made for the MPGN2000 stations. Thus, with the availability of GDM2000 (2009) coordinates for all the MyRTKnet stations, the next step is to revise the GDM2000 coordinates of the MPGN2000 stations, bearing in mind that stations in Sabah and Sarawak still maintain their GDM2000 coordinates due to insignificant displacements from the two earthquakes in Sumatra.
MPGN2000 (2009) !
Results indicate that the coordinate displacement of the MPGN2000 network in Peninsular Malaysia is not linear and displays elastic properties. In addition, the displacements also differ from one station to another. Thus, any type of modelling of the actual displacement needs a long period of monitoring in order to produce precise parameter. As an alternative, a multiple regression model was thus produced using GPS data obtained from 2009 to provide a relationship between the MPGN2000 in GDM2000 and MPGN2000 in GDM2000 (2009). Tests indicate that through the re-observations at selected MPGN2000 stations and connection to the MyRTKnet stations is at cm-level accuracy.
