MyGEOiD by hubspot-directory.blogspot.com
Upcoming SlideShare
Loading in...5
×
 

Like this? Share it with your network

Share

MyGEOiD by hubspot-directory.blogspot.com

on

  • 594 views

MyGEOiD by hubspot-directory.blogspot.com

MyGEOiD by hubspot-directory.blogspot.com

Statistics

Views

Total Views
594
Views on SlideShare
594
Embed Views
0

Actions

Likes
0
Downloads
12
Comments
0

0 Embeds 0

No embeds

Accessibility

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

MyGEOiD by hubspot-directory.blogspot.com Presentation Transcript

  • 1. SeminarSeminar RTKNetRTKNet dandan PetaPeta GeoidGeoid Kuala LumpurKuala Lumpur –– 12 May 200512 May 2005 My GEOIDMy GEOID -- LOCAL GEOIDLOCAL GEOID DETERMINATIONDETERMINATION for MALAYSIAfor MALAYSIA Seksyen Geodesi, Bahagian Pemetaan Department of Survey and Mapping Malaysia Jalan Semarak 50578 KUALA LUMPUR Telephone: +603-26170800 Fax: +603-26933618 E-mail: geodesi@jupem.gov.my WWW: http://www.jupem.gov.my/
  • 2. CONTENTS 1. Introduction 2. Geoid computation 3. MyGEOID – Malaysia Geoid 4. Conclusion 5. Recommendations
  • 3. INTRODUCTION MAIN GOAL AMONG RESEARCHES IN THE GEODETIC COMMUNITY -the determination of geoid with high accuracy VISION - With the generalized use of GPS, the convenience of obtaining orthometric heights without doing levelling
  • 4. INTRODUCTION JUPEM’S LONG TERM GOAL The determination of accurate geoid for -Peninsular Malaysia -Sabah and Sarawak To replace levelling in the near future IMPORTANT STEPS TOWARDS THIS GOAL -A thorough analysis of all available data in the regions -Proper method for geoid determination
  • 5. GEOID COMPUTATION PRECISE GEOID COMPUTATION INFLUENCED BY -Physical terrain and bathymetry characteristics of the regions -Establishment of high resolution mean free air gravity anomaly database for the regions -Need for Digital Terrain Model (DTM) in order to correct the terrain effects -Vertical datums for the regions
  • 6. GEOID COMPUTATION General Methodology B. Using the remove-restore method. The effect of a spherical harmonic expansion and topography is removed from the data & subsequently added to the results A. Transform all data to a global geodetic datum (GRS80/WGS84) RESIDUAL DATA E. Determine using LSC a (regional) gravity field approx’n Compute estimates of the geoid heights and their errors D. Make a homogeneous selection of the data for geoid computation - Check for gross errors (make contour map of data) - Verify error estimates C. Determine a statistical model (a covariance function) for the residual data For that particular region F. If the error is too large and more data is available Add new data and repeat E. G. Check Model By comparison with data not used to obtain the model
  • 7. GEOID COMPUTATION GRAVSOFT’s Programs used Function Program Name Make reference grids of EGM96 ref. fields harmexp Acquire & merge terrestrial gravity data & DEMs geogrid/gomb/geoip Terrain-reduce airborne and surface gravity data Tc Downward continue airborne gravity data to regular grid on geoid, and merge with satellite altimetry data gpcol/gpcol1 Apply spherical FFT for geoid determination spfour Compute and restore terrain and EGM effects to obtain final gravimetric geoid spfour/geoip Fit geoid to GPS-levelling geoip/geogrid/gcomb
  • 8. MyGEOID GEOID COMPUTATION For Peninsular Malaysia
  • 9. GEOID COMPUTATION GRAVIMETRIC GEOID Pen. Malaysia [ WMG03A Model ] The WMG03A geoid model is a purely gravimetric, geocentric geoid model covering Peninsular Malaysia A total of 960 X 1080 points with terrestrial, airborne & altimetry gravity measurements 3 arc second JUPEM’s DTED and 15” interpolated SRTM The GGM01C global Geopotential Model 99.5 100 100.5 101 101.5 102 102.5 103 103.5 104 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 -19 -17 -15 -13 -11 -9 -7 -5 -3 -1 1 3 5 7 9 11 INPUT DATA WMG03A Model
  • 10. GEOID COMPUTATION GRAVIMETRIC GEOID Pen. Malaysia [ WMG03A Model ] COMPUTATION Using Grace GGM01C as an underlying long wavelength model, WMG03A was computed using 1-D FFT remove/ compute/restore application of the spherical Stoke’s integral. The WMG03A geoid undulations refer to a geocentric GRS-80 ellipsoid. WMG03A was computed on a 1.5 X 1.5 arc minute grid (≈2.6km), covering Pen. Malaysia in the region 0-8° N latitude and 98-107°E longitude. 99.5 100 100.5 101 101.5 102 102.5 103 103.5 104 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 -19 -17 -15 -13 -11 -9 -7 -5 -3 -1 1 3 5 7 9 11 WMG03A Model
  • 11. MyGEOID – Malaysia Geoid Mean Sea Level for Pen. Malaysia (NGVD1) • Based on Port Klang Tide Gauge. • 10 years observation • Datum Level defined by Indian Spring Low Water MSL for Sabah & Sarawak (NGVD2) • Based on various Tide Gauges in Sabah & Sarawak . • 10 years observation • Datum Level defined by Indian Spring Low Water
  • 12. MyGEOID – Malaysia Geoid Difference Between NGVD & Gravimetric Geoid
  • 13. MyGEOID – Malaysia Geoid H (NGVD) vs H (h [GPS] - N [Gravimetric Geoid]) What is the Differences ? 0.4 – 0.9 meter for Peninsular Malaysia 1.0 – 1.5 meter for East Malaysia Why the Differences ? Gravimetric Geoid referred to Global Mean Sea Level, whereas Levelling height based on the local Mean Sea Level. The differences also known as Vertical Datum Bias.
  • 14. MyGEOID – Malaysia Geoid OBJECTIVE – to fit gravimetric geoid to NGVD • To fit the computed gravimetric geoid onto NGVD (local MSL) • Requirement for this fitting: • GPS Observation on Benchmarks • Adjusted Values of Benchmarks • Accuracy of GPS Observations : 3 cm • Accuracy of BM Values : 3 cm • To use Collocation Technique • To achieve Absolute Accuracy < 4 cm
  • 15. MyGEOID – Malaysia Geoid MyGEOID for Pen. Malaysia [WGeoid04 Model ] 99.5 100 100.5 101 101.5 102 102.5 103 103.5 104 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 The WGeoid04 geoid model is a hybrid geoid model, combining the gravimetric geoid with datum transformations and 53 GPS ellipsoidal heights on NGVD1 levelled bench marks. WGeoid04 Model
  • 16. MyGEOID – Malaysia Geoid Testing & Analyses of WGeoid04 Model 1997 Johor Data Set Height Difference (Derived - Published) -0.300 -0.250 -0.200 -0.150 -0.100 -0.050 0.000 0.050 0.100 0.150 0.200 0.250 0.300 J0060 J0087 J0141 J0151 J0184 J0241 J0249 J0260 J0416 J0481 J0484 J0552 J0584 J0617 J0678 J0695 J0700 J0766 J0782 J0831 J1037 J1133 J1199 J1220 J1236 J1249 J1275 J1330 J1377 J1444 J1513 J1609 S0015 S0073 S0992 Benchmark HeightDifference(m) Total Data Set = 35 Total Number of Rejected Data = 2 Percentage of Rejected Data = 5.7% RMS=0.042 m.
  • 17. MyGEOID – Malaysia Geoid Testing & Analyses of WGeoid04 Model 2003 Johor Data Set 102.6 102.8 103 103.2 103.4 103.6 103.8 104 104.2 Longitud 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 Latitud P114 GP15 GP16 GP47 GP49 GP50 GP59 GP61 GP84 GP85 SEGA UTMJ Taburan Stesen Cerapan GPS Projek Cerapan GPS Tanda Aras Stesen MASS Stesen GPS Tanda Aras Height Difference (Derived - Published) -0.300 -0.250 -0.200 -0.150 -0.100 -0.050 0.000 0.050 0.100 0.150 0.200 0.250 0.300 J0022 J0077 J0249 J0412 J0483 J0649 J0699 J0915 J0921 J0924 J1046 J1082 J1261 J1349 J1358 J1365 J1375 J1423 J1427 J1450 J1513 J1523 J1527 J1562 J1577 J1593 J1655 J1667 J1685 J1692 J1699 J1712 J1731 J1740 J1767 J1774 J1876 J2507 J2566 J2676 J3122 J3136 J3146 J3275 Benchmark HeightDifference(m) Total Data Set = 44 Total Number of Rejected Data = 7 Percentage of Rejected Data = 15.9 % RMS=0.042 m.
  • 18. MyGEOID – Malaysia Geoid Testing & Analyses of WGeoid04 Model 100.4 100.6 100.8 101 101.2 101.4 101.6 101.8 3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 A0085 A0089 A0092 A0123 A0152A0363 A0424 A0470 A0500A0585 A0600 A0635 A0701 A0726 A0809 A0811 A0832 A0840 A0933 A0974 A0979 A0983 A1141 A1285 A1347 A1381 A1396 A1555 A1597 A1601 A1606 A1622 A1703 A1802 A1831 A1839 GP02 GP07 GP82 P101 P102 P203 P205 P207 P210 P270 P274 P280P281 P286 S0091 S0294 S0376 S0379 S0411 S0461 S0462 Height Difference (Derived - Published) Perak -0.300 -0.250 -0.200 -0.150 -0.100 -0.050 0.000 0.050 0.100 0.150 0.200 0.250 0.300 A0085 A0089 A0092 A0123 A0152 A0363 A0424 A0500 A0585 A0600 A0635 A0701 A0726 A0832 A0840 A0933 A0974 A0979 A0983 A1285 A1381 A1396 A1555 A1597 A1601 A1606 A1622 A1802 A1831 A1839 S0091 S0376 S0379 S0411 S0461 S0462 Benchmark HeightDifference(m) Total Data Set = 36 Total Number of Rejected Data = 4 Percentage of Rejected Data = 11.1 % RMS=0.038 m. 1997 Perak Data Set
  • 19. MyGEOID GEOID COMPUTATION For Sabah and Sarawak
  • 20. GEOID COMPUTATION GRAVIMETRIC GEOID Sabah & Sarawak [ EMGG03C Model ] The EMGG03C geoid model is a purely gravimetric, geocentric geoid model covering Sabah and Sarawak INPUT DATA EMGG03C Model A total of 1800 X 1080 points with airborne & altimetry gravity data 15 arc second of interpolated SRTM The GGM01C global Geopotential Model
  • 21. GEOID COMPUTATION GRAVIMETRIC GEOID Sabah & Sarawak [ EMGG03C Model ] COMPUTATION Using GGM01C as an underlying long wavelength model, EMGG03C was computed using 1-D FFT remove/ compute/restore application of the spherical Stoke’s integral. EMGG03C Model The EMGG03C geoid undulations refer to a geocentric GRS-80 ellipsoid. EMGG03C was computed on a 3 X 3 arc minute grid (≈5.0km), covering Sabah and Sarawak in the region 0-8.5° N latitude and 106-120.5°E long.
  • 22. BACKGROUND – Vertical Datum for Sabah and Sarawak • Using 7 difference vertical datums o Sabah97 (Kota Kinabalu 1997) for Sabah o Sabah Datum for Lawas (Sarawak) o Merapok for Lawas (Sarawak) o Jabatan Laut Tide stations for Limbang (Sarawak) o Original for Miri (Sarawak) o Bintulu (Sarawak) o Pulau Lakei (Sarawak)
  • 23. VERTICAL DATUM UNIFICATION – NGVD2 108 109 110 111 112 113 114 115 116 117 118 119 120 0 1 2 3 4 5 6 7 8 A102 TKIN TLAB 1691 TKUCH TSAN TLHD TTAW TBIN • Analyses on all tide stations • All stations connected by GPS Levelling technique
  • 24. NGVD2 Mean Sea Level Kota Kinabalu 1988 - 2003 2.509 2.509 2.482 2.462 2.466 2.478 2.490 2.514 2.540 2.479 2.498 2.580 2.582 2.581 2.529 2.526 2.400 2.420 2.440 2.460 2.480 2.500 2.520 2.540 2.560 2.580 2.600 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 Year MSL(meter) Yearly Mean Sea Level Mean Sea Level 1988 - 2003 Mean Sea Level 1988 - 1997 MSL 1988 - 2003 = 2.514 meter MSL 1988 - 1997 = 2.493 meter • Based on Tide observation in Kota Kinabalu, Sabah • 10 years observation 1988 – 1997
  • 25. NGVD2 - Datum Transfer 110 111 112 113 114 115 116 117 118 119 0 1 2 3 4 5 6 7 A102 TKIN TLAB 1691 1805 2505 TKUCH TSAN TLHD TTAW TBIN LEGEND Precise Levelling Technique GPS Levelling Technique Tide Stations/Std. BM DATUM TRANSFER Sabah & Sarawak • Precise Levelling Technique • GPS Levelling Technique
  • 26. NGVD2 - Datum Transfer GPS Observation on Tide Stations 107 108 109 110 111 112 113 114 115 116 117 118 119 120 0 1 2 3 4 5 6 7 8 A102 TKIN TLAB 1691 1805 2505 TKUCH TSAN TLHD TTAW TBIN775 km 440 km 280 km 195 km 143km 119 km 126km 270 km 267 km 271 km • Three days continuous GPS observation • Using Bernese Software for data processing • Served as a check for Levelling Network
  • 27. 110 111 112 113 114 115 116 117 118 119 0 1 2 3 4 5 6 7 A102 TKIN TLAB 1691 TKUCH TSAN TLHD TTAW TBIN LEGEND Precise Levelling Route Second Order Levelling Route GPS Levelling Tide Stations LEVELLING NETWORK 2004 Sabah & Sarawak NGVD2 – Levelling Network • Consists of Precise Levelling Net, Second Order Net and GPS Levelling Technique
  • 28. NGVD2 – Datum Offset No. Datum Offset fromNGDV2(m) 1. Sabah97 0.000m 2. Sabah(Lawas) -0.161m 3. Merapok(Lawas) -0.158m 4. STAPSJab. Laut (Limbang) -0.317m 5. Original (Miri) -0.144m 6. Bintulu(Bintulu) -0.357m 7. PulauLakei -0.351m
  • 29. EMGM05A – Fitted Geoid Model for Sabah and Sarawak 110 111 112 113 114 115 116 117 118 119 0 1 2 3 4 5 6 7 LEGEND GPS Permanent Stations GPS Stations Tide Stations Benchmarks GPS on BENCHMARK PROJECT Sabah & Sarawak • 74 BMs in Sarawak • 46 BMs in Sabah • 27 GPS stations • 8 Mass stations
  • 30. EMGM05A – Fitted Geoid Model for Sabah and Sarawak • Final model based on 60 SBM/BMs from NGVD2 • Iterative process by excluding minimal SBM/BM on each iteration • Formal Error = 2.9 cm • Corrector surface range from 1.1 – 1.5 meter
  • 31. EMGM05A – Final Model 107 108 109 110 111 112 113 114 115 116 117 118 119 120 0 1 2 3 4 5 6 7 8 2 12 22 32 42 52 62
  • 32. EMGM05A – Testing & Analyses 110 111 112 113 114 115 116 117 118 119 0 1 2 3 4 5 6 7 KUCH KINA LABU BINT MIRI SAND MTAW SIBU LEGEND BMs with Residuals < 0.045 m (RMS) BMs with Residuals > 0.045 m (RMS) GPS Permanent Stations EMGG05A Test Network Height Difference (Derived - Published) Sabah And Sarawak -0.300 -0.200 -0.100 0.000 0.100 0.200 0.300 TA60038 TA1028 TA90005 TA40077 TA40025 TA30116 TA30069 TA1570 SBM5 SBM21 SBM55 SBM14 ST70 SS0071 SS0182 SA0355 SU0401 SU0506 SA0516 SU0527 SK1019 ST5113 S008 S010 S047 • Total Data Set = 25 • Total Number of Rejected Data = 11 • Percentage of Rejected Data = 44 % • RMS = 0.041 m
  • 33. Conclusion: • WGeoid04 fitted using 37 SBM/BM (36 SBM & 1 BM) with formal error of 0.020 m • WGeoid04 accuracy based on test data = 0.042 m (RMS) • EMGG05A fitted using 60 SBM/BM formal error of 0.029 m • EMGG05A accuracy based on test data = 0.041 m (RMS) • Suitable for : • Engineering Survey • Rapid detection of BM stability • Rapid determination of height reference (SBM/BMs/TBM) • Topographical Mapping & Profiling
  • 34. Recommendations: WGeoid04 (P. Malaysia) • GPS Levelling Network Densification, Baseline ≈ 30 km • Levelling Route Investigation, Cameron Highland & Sg. Rengit • Re-adjustment of Precise Levelling Network • Realization of 1cm Geoid Model
  • 35. Recommendations: EMGG05A (Sabah & Sarawak) • GPS Levelling Network Densification, Baseline ≈ 30 km • Ground Truth GPS Survey for Quality/Accuracy Assessments • Adding More BMs/SBMs that cover the whole Sarawak, simultaneously with the Ground Truth GPS Survey • Investigation on second order levelling route • Precise levelling connecting all tide gauge stations in Sarawak • Realization of 1cm Geoid Model