Who s heard of the GDA2020?

Transcription

1 Implications of a next generation datum in Australia on mining operations: A discussion. School of Civil & Environmental Engineering Craig Roberts Senior lecturer Surveying and Geospatial Engineering group Japan-Australia Australian Institute Workshop of Mining on Surveyors, Joint QZSS Annual Projects, conference, Sydney, Australia, Sydney July August Who s heard of the GDA2020? 1

2 Courtesy John Dawson Geoscience Australia Courtesy John Dawson Geoscience Australia 2

3 Who s heard of the ITRF? International Terrestrial Reference Frame The$Interna*onal$Terrestrial$ Reference$Frame$(ITRF)$ 6" Courtesy Joel Haasdyk 3

4 International Terrestrial Reference Frame Four main geodetic techniques are used to compute accurate coordinates: GPS, VLBI, SLR, and DORIS. Since the tracking network equipped with the instruments of those techniques is evolving and the period of data available increases with time, the ITRF is constantly being updated. 11 realizations of the ITRS were set up from The latest is the ITRF2008. All these realizations include station positions and velocities. Who s heard of the IGS? International GNSS Service 4

5 IGS network: a subset of ITRF International GNSS Service (IGS) 5

6 International GNSS Service The IGS collects, archives, and distributes GPS and GLONASS observation data sets of sufficient accuracy to meet the objectives of a wide range of scientific and engineering applications and studies. These data sets are analyzed and combined to form the IGS products. Glonass orbits IGS Tracking stations coordinates Velocities? 6

7 We all know GDA94 Can get coordinates from SCIMS (NSW) Geocentric Datum of Australia GDA94! The Geocentric Datum of Australia (GDA) is the new Australian coordinate system, replacing the Australian Geodetic Datum (AGD). GDA is part of a global coordinate reference frame and is directly compatible with GPS.! It is based on the International Terrestrial Reference Frame 1992 (ITRF92) held fixed at 1 January 1994 hence the name GDA94.! The 8 points used to define the GDA94 are known as the Australian Fiducial Network (AFN). The adopted coordinates of the AFN were computed in terms of the ITRF and from these AFN coordinates the geodetic network that covers the whole continent was recomputed. Courtesy Geoscience Australia 7

8 Australian Fiducial Network (AFN) Australian National Network (ANN) consists of 78 stations at an approx 500km spacing ( ). GDA94 Gazetted coordinates of the AFN 8

9 National Geospatial Reference System GDA94 densified under Auscope project We ve all used CORS networks Continuously Operating Reference Station networks 9

10 CORSnet-NSW All Day RTK Position Partners 10

11 SmartNetAUS - Leica All give coordinates in GDA/MGA. ever noticed a difference between CORS derived coordinate and SCIMS coordinate? 11

12 GDA94:$problems,$issues,$complica*ons$ Modelling$known$distor*ons$e.g.$NSW$SCIMS$to$GDA94(2010)$ Distor+ons"are"Systema+c" Site$transforma*ons$or$ Localisa*ons $are$currently$used$to$account$for$distor*ons$ Transforma+on"tools"must"be"developed"(e.g."NTv2"Grid)"" " "AND"these"must"es+mate"uncertainty" (Joel$Haasdyk$and$Tony$Watson,$LPI$NSW,$APAS$Conference$2013)$ 23" Ever used AUSPOS? 12

13 AUSPOS V2.0 uses the Auscope network giving 20mm positions with one hour of date. Coordinates given in ITRF, GDA and MGA. AUSPOS output 13

14 Ever used PPP? Precise point positioning 14

15 Post-Processed PPP Canadian System NRCAN s online CSRS-PPP Is this MGA94? Courtesy Thomas Grinter Ever used Trimble RTX? Hybrid differential/ PPP service 15

16 Trimble CentrePoint RTX Combines NRTK and PPP (Precise Point Positioning). Released in Worldwide system: Sparse global CORS network: All Trimble receivers: Same make. Same model. Same firmware. Same antennas. Same setup/install. Services delivered by: Satellite communications (via OmniSTAR). Mobile communications (worldwide). <4 cm HZ (95% CI) positioning worldwide. Example output from Trimble s RTX 16

17 What about WGS84? World Geodetic System 1984 (WGS84) Z-Axis = The direction of the IERS Reference Pole (IRP), corresponds to the direction of the BIH Conventional Terrestrial Pole CTP (epoch ) with an uncertainty of X-Axis = Intersection of the IERS Reference Meridian (IRM) and the plane passing through the origin and normal to the Z-axis. The IRM is coincident with the BIH Zero Meridian (epoch ) with an uncertainty of WGS84 coordinates move with ITRF 17

18 Shapes, Datums and Grids Shape connection Datum projection Map Grid ANS Johnston AGD66 UTM AMG66 ANS Johnston AGD66 TM ISG (2 zones) ANS Johnston* AGD84 UTM AMG84 Static GRS80 AFN GDA94 UTM MGA94 WGS84 control WGS84 UTM WGS84 (grid??) GRS80 IGS ITRF2008 UTM ITRF (grid??) Note: For most intents and purposes, ITRF2008 and WGS84 are considered identical. Next Generation Datum! New mass market or niche positioning services may or may not offer MGA coordinates! Surveyors must know from which datum and epoch their solutions derive metadata.! Dawson/Woods parameters cater for stable plate movements. They do not account for intra-plate deformations. 18

19 Drivers for Datum modernisation current datum is not good enough 300"mm" Distor+ons!" " 50"mm" Courtesy Joel Haasdyk Drivers for Datum modernisation deformation demands datum maintenance Meckering,"WA" Oct"1968" Canterbury","NZ" 2010/11" Courtesy Joel Haasdyk 19

20 Drivers for Datum modernisation demand for high quality spatial data is insatiable Imagery" Eleva+on" Transport/" U+li+es" Addresses" Boundaries" Water" Survey"Control" (Datum)" Courtesy Joel Haasdyk The"Real"World" Real-time precise positioning has becomes easy(er)... the datum must respond to changes in technology Frequency of national adjustment 2010$ 2015$ 2020$ $$$$$Time$ Defined" 1997" GDA94" Courtesy Joel Haasdyk Interim" GDA2020 " SemiYdynamic" Epoch:"2020.0" +"Deforma+on" " ReYadjust"Annually" ATRF" " Dynamic" Epoch:"Current" +"Deforma+on" $ ReYadjust"Daily?" Weekly?" As"required?" 20

21 New Software and Hardware DynaNet" Phased$Adjustment $ No$limit$on$sta*ons$ No$limit$on$measurements$ Rigorous$Adjustment$ $$$"$Coordinates$+$Uncertainty$ Courtesy Joel Haasdyk egeodesy" XML$based$on$GML$ Transfer$of$data$and$ results$ " $ Na+onal"Compu+ng" Infrastructure"(NCI)$ $$$$$$$400,000$sta*ons$ +$2,500,000$measurements$ $$$$$$$$$$$$$$$$25$hours$to$adjust$ The Finer Details: Options to Consider $ $ $ $ 1. Adopt a modern, homogenous, national adjustment 2. Update from ITRF92 to latest ITRF 3. Choice of Static / Semi-Dynamic / Dynamic Datum 4. Choice of Reference Epoch (Past, Present, or Future) 5. Choice of Deformation Model 6. Frequency of National Adjustment Courtesy Joel Haasdyk 21

22 Static vs. Semi-Dynamic vs. Dynamic The ideal world! The next best thing Reality Complex deformation Dynamic Position Complex Simple Semi-dynamic [NZGD2000] Semi-dynamic [ETRF89] Reference Epoch ) Time Static Datum [GDA94] Courtesy Joel Haasdyk 18 th Association of Public Authority Surveyors Conference 12Z14$March$2013,$Canberra,$ACT,$Australia$ How does a next generation datum affect mining surveyors and mining operations?! Correlation of surface and underground mining operations! Open cut operations over long periods of time! Currently legislation requiring MGA at some/all mines in NSW! AHD 10,000m at some mines 22