Absolute & Relative GPS Orthometric Heights using Regional Fitted Geoid

Transcription

1 bsolute & Relative GPS Orthometric eights using Regional Fitted Geoid KMLUDDIN j Talib 1,SIFUL MNj Sulaiman 1, JSMEE Jaafar 1 MOD ZINEE Zainal 1 & ZRI Mohamed 2 1 Universiti Teknologi MR, Malaysia 2 Department Survey and Mapping Malaysia khtalib@salam.uitm.edu.my Commission No.5 Overview INTRODUCTION BSIC GPS/GNSS EIGT BSOLUTE ND RELTIVE GPS/GNSS EIGT STUDY RE ND DTSET FIELD OBSERVTION ND PROCESSING RESULT ND NLYSIS CONCLUSION CKNOWLEDGEMENT 1

2 INTRODUCTION Classical equipment and method of observation in determination of height is labor intensive and time consuming. It also highly dangerous and tedious. GPS/ GNSS technology can be used as a tools for horizontal and height determination. GPS/GNSS ellipsoidal height can easily transform to orthometric height by having a Geoid Model. MyGEOID-Malaysia Geodetic Infrastructure developed and maintain by DSMM with RMS=±3cm INTRODUCTION Two(2) GPS/GNSS height concept can be used in determination of orthometric height; bsolute and Relative The accuracy of both technique will be examine and evaluate in this study. 2

3 BSIC GPS/GNSS EIGT FORMUL Where: = h N = Orthometric eight h = Corrected Ellipsoidal eight N= Geoid eight (MyGEOID) BSOLUTE ND RELTIVE GPS EIGT bsolute GPS eight Concept = h N = Orthometric eight of point h = Corrected Ellipsoidal eight of point N = Geoid eight (MyGEOID) of point 3

4 BSOLUTE ND RELTIVE GPS EIGT Relative GPS eight Concept Where: = h N ± ε = Orthometric eight of Point h = Corrected Ellipsoidal eight at Point N = Geoid eight of Point. ε = Where: SBM ( GPS) SBM ( Leveling) SBM(GPS) = Computed Orthometric eight of Point SBM SBM(leveling) = Orthometric eight of Point SBM by leveling STUDY RE ND DTSET Consists of 8000km 2 (Negeri Sembilan and Melaka) 14 randomly selected standard benchmark Leveling data based on NGVD 4

5 FIELD OBSERVTION ND PROCESSING Field Observation Parameter Items Parameter Equipment Trimble R8 Geodetic grade Tripod 2 meter fixed pole Elevation Mask 0 Mode Observation Static Period of Obsevation min 3 ours Record Inverval 15 sec Observation Datum WGS84 FIELD OBSERVTION ND PROCESSING Processing Parameter Items Parameter General Procedure Prescribed procedures as provided in manufacturer manual must be followed Datum GDM2000 Elevation Mask 15 Ephemerides Baseline Processing Short baseline of less than 30 km: Broadcast Long baseline: Precise RMSE less than 3 cm Quality Maximum data rejection - less than 10 % djustment Minimally Constrained djustment mbiguity fixed solution Least square adjustment should be used One control station fixed in GDM2000 coordinates Quality Indicator Over-Constrained djustment Pass Chi-squares test at 95% confident region ll baselines must pass the local test t least 2 control stations must be fixed in the final adjustment 5

6 RESULT ND NLYSIS Different = GPS BM/SBM Where : GPS BM/SBM = eight Derived Based GPS Observation (= h-n) = eight from Leveling Network RESULT ND NLYSIS bsolute GPS eight Concept Ellipsoidal eight STD Error of Ellip. eight Orthometric eight SBM eight Diff Point ID (Meter) (Meter) (Meter) (Meter) (Meter) E N S S S S S S S S S S S S Min Max RMS

7 RESULT ND NLYSIS Relative GPS eight Concept From -To Length Ellipsoidal eight STD Error of Ellip. eight Orthometric eight SBM eight (Meter) (Meter) (Meter) (Meter) (Meter) (Meter) E S E S E S N S N S N S N S S0108- S S S S S S S Min Max RMSE ±0.034 Diff CONCLUSION ccuracy of absolute GPS height concept : 11.5cm RMS ccuracy of relative GPS height concept : 3.4cm RMS Relative GPS height concept higher accuracy compared absolute GPS height concept. Both of this GPS concept can be applied to engineering works. 7

8 cknowledgement Financial assistance from Malaysian Land Surveyors Board (LJT). Department of Survey and Mapping Malaysia- Universiti Teknologi MR, Malaysia Thank you for your attention! Center of Studies Surveying Science and Geomatics Faculty of rchitecture, Planning and Surveying Universiti Teknologi MR, Malaysia Shah lam 8