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Japan-Australia Workshop on Joint QZSS Projects, Sydney, Australia, 11 July 2014 Australian Institute of Mining Surveyors, Annual conference, Sydney 14-15 August 2014

School of Civil & Environmental Engineering

Implications of a next generation datum in Australia on mining

operations: A discussion.

Craig Roberts

Senior lecturer Surveying and Geospatial

Engineering group

Who’s heard of the GDA2020?

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Courtesy John Dawson Geoscience Australia

Courtesy John Dawson Geoscience Australia

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Who’s heard of the ITRF ?

International Terrestrial Reference Frame

6"

The$Interna*onal$Terrestrial$Reference$Frame$(ITRF)$

Courtesy Joel Haasdyk

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International Terrestrial Reference Frame

http://itrf.ensg.ign.fr/GIS/index.php

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 1988. The latest is the ITRF2008. All these realizations include station positions and velocities.

Who’s heard of the IGS ?

International GNSS Service

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IGS network: a subset of ITRF

http://igscb.jpl.nasa.gov/components/prods_cb.html

International GNSS Service (IGS)

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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?

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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

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Australian Fiducial Network (AFN)

Australian National Network (ANN) consists of 78 stations at an approx 500km spacing ( ).

GDA94 – Gazetted coordinates of the AFN

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National Geospatial Reference System

GDA94 densified under Auscope project

We’ve all used CORS networks

Continuously Operating Reference Station networks

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CORSnet-NSW

All Day RTK – Position Partners

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SmartNetAUS - Leica

All give coordinates in GDA/MGA

…. ever noticed a difference between CORS derived coordinate

and SCIMS coordinate?

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23"

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$2013)$

GDA94:$problems,$issues,$complica*ons$Modelling$known$distor*ons$e.g.$NSW$SCIMS$to$GDA94(2010)$

Ever used AUSPOS ?

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AUSPOS V2.0 uses the Auscope network giving 20mm positions with one hour of

date. Coordinates given in ITRF, GDA and MGA.

http://www.ga.gov.au/earth-monitoring/geodesy/auspos-online-gps-processing-service.html

AUSPOS output

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Ever used PPP ?

Precise point positioning

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Post-Processed PPP – Canadian System

NRCAN’s online CSRS-PPP http://webapp.csrs.nrcan.gc.ca

Courtesy Thomas Grinter

Is this MGA94?

Ever used Trimble RTX ?

Hybrid differential/ PPP service

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Trimble CentrePoint RTX

Combines NRTK and PPP (Precise Point Positioning). Released in 2012. 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

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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 1984.0) with an uncertainty of 0.005″

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 1984.0) with an uncertainty of 0.005″

…. WGS84 coordinates move with ITRF

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ANS → Johnston → AGD66 → UTM → AMG66

ANS → Johnston → AGD66 → TM → ISG – (2° zones)

ANS → Johnston* → AGD84 → UTM → AMG84

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.

Shapes, Datums and Grids Shape → connection → Datum → projection → Map Grid

Stat

ic

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.

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Drivers for Datum modernisation current datum is not good enough

50"mm"

300"mm"

Distor+ons!""

Courtesy Joel Haasdyk

Drivers for Datum modernisation deformation demands datum maintenance

Meckering,"WA"

Oct"1968"

Canterbury","NZ"

2010/11"

Courtesy Joel Haasdyk

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Imagery"

Eleva+on"Transport/"

U+li+es"Addresses"

Boundaries"

Water"

Survey"Control"

The"Real"World"

Drivers for Datum modernisation demand for high quality spatial data is insatiable

Real-time precise positioning has becomes easy(er) ... the datum must respond to changes in technology

(Datum)"

Courtesy Joel Haasdyk

Frequency of national adjustment

$$$$$Time$

GDA94"

2010$ 2015$ 2020$

Interim"‘GDA2020’"

SemiYdynamic"

Epoch:"2020.0"

+"Deforma+on"

"

ReYadjust"Annually"

"

Dynamic"

Epoch:"Current"

+"Deforma+on"

$ReYadjust"Daily?"

Weekly?"

As"required?"

Defined"

1997"

ATRF"

Courtesy Joel Haasdyk

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New Software and Hardware

DynaNet"‘Phased$Adjustment’$

• No$limit$on$sta*ons$• No$limit$on$measurements$• Rigorous$Adjustment$$$$"$Coordinates$+$Uncertainty$

Na+onal"Compu+ng"

Infrastructure"(NCI)$$$$$$$$400,000$sta*ons$+$2,500,000$measurements$$$$$$$$$$$$$$$$$25$hours$to$adjust$

eGeodesy"• XML$based$on$GML$• Transfer$of$data$and$results$

"

$Courtesy Joel Haasdyk

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

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Static vs. Semi-Dynamic vs. Dynamic

18th Association of Public Authority Surveyors Conference 12Z14$March$2013,$Canberra,$ACT,$Australia$

Time

P

ositi

on

Reality… Complex deformation The ideal world! The next best thing…

Reference Epoch

‘1994.0)

Semi-dynamic [NZGD2000]

Dynamic

Semi-dynamic [ETRF89]

Static Datum [GDA94]

Simple

Complex

Courtesy Joel Haasdyk

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