Geodesy
Status of ICSM Projects
Geocentric Datum of Australia (GDA)
The Australian Geodetic Datum (AGD), established in 1966 and updated in 1984, has been replaced by the Geocentric Datum of Australia (GDA) that is compatible with the WGS84 system used with GPS. More information on GDA can be found at ICSM's GDA page.
 Computation of GDA coordinates for the AFN and ANN sites - completed 11 November 1994
GDA notified in Commonwealth Gazette - completed 6 September 1995
Adjustment of the combined State & Territory geodetic networks
Preliminary adjustment - completed 13 December 1996
Final adjustment - completed 23 March 1997
National Geodetic Data Base updated with GDA94 coords from the State& Territory geodetic networks adjustment - completed 2 June 1997
Western Australian GPS network (StateFix) adjusted to the AFN and ANN - completed May 1997
National Molodensky transformation parameters (AGD84& AGD66 <-> GDA94), computed using the GPS stations from the Combined State& Territory adjustment, are available in the GDA Technical Manual (see below). They are suitable for basic applications (~ 2-5 metres). - completed 5 August 1997
National Similarity transformation parameters (AGD84 <-> GDA94), computed using the GPS stations from the Combined State& Territory adjustment, are also available in the GDA Technical Manual (see below). They are suitable for low accuracy applications (~ 1 metre).- completed 3 September 1997
The on-line GDA Technical Manual on ICSM's WWW wqas completed 5 May 1998. There have been several updates since the initial version.
National transformation grids from AGD66& AGD84 to GDA94 were released on 5th October 2001.
These high accuracy transformation grids are the recommended transformation method. More information, including links to the grid files and interpolation software, are available in Chapter 7 of the GDA Technical Manual. The final report describing the development of these grids is also available.
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Standards and Practices for Control Surveys (SP1)
An important part of ICSM's role is to maintain and develop technical publications. ICSM, through the Geodesy Technical Sub-committee, updated its technical publication 'Standards and Practices for Control Surveys (SP1)'.
Version 1.3 of SP1 available on the ICSM WWW - 30 January 1997
SP1 modified to clarify CLASS - 10 March 1997
SP1 V1.4 released in PDF format - 22 December 2000
SP1 V1.5 released in PDF format - May 2002
SP1 V1.6 released in PDF format - Novembetr 2004
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Best Practice Guidelines for the Use of the Global Positioning System (GPS) for Surveying Applications
With the increasing use of GPS for land measurement, a national system of legal traceability within the Australian legal system is required. ICSM has pursued this matter through the National Standard's Commission. The Best Practice Guidelines were produced as an interim measure.
Version 1 of guidelines released - 1 May 1996
Version 1.1 of guidelines released - 1 October 1996
Version 2.0 of guidelines released - 1 November 1997
Guidelines included in Part B of ICSM's Special Publication 1 (SP1) 1 November 2000
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Legal Traceability of GPS Measurements
Submission to National Standards Commission (NSC) requesting NSC to examine the scope for acceptance of 'position' under the National Measurement Act (1960) - 5 June 1996
The Australian Government Solicitor advised NSC that the Commission is able to make a determination of the AFN positions as a recognized-value standard of measurement under the National Measurement Act (1960) - 1 September 1997
NSC determination of the AFN positions as a recognized-value standard of measurement at Commission meeting - 11 September 1997
The AFN positions were gazetted as a recognised-value standard of measurement on 22 April 1998.
NSC appoints GeoScience Australia as a Verifying Authority for the measurement of positions - 22 May 2000. Some other jursidictions are planning to seek similar appointment.
Procedures for the verification of positions by Verifying Authorities can be found on the NSC web (search for VAH).
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Geodetic Support for Mean Sea Level Monitoring
ICSM, through the Geodesy Technical Sub-committee, provides support for the monitoring of mean sea level, by periodic optical levelling between the National Tidal Centre's array of tide gauges and the coastal array of bench marks. Geoscience Australia maintains the history of these connections on its web site.
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Absolute Accuracy for Positions
'Positional Uncertainty' and 'Local Uncertainty' has been adopted by ICSM and is included in SP1 V1.5.
ANZLIC's MetaData Working Group has these items under consideration for inclusion in their updated MetaData Guidelines. The proposal is compatible with the draft ISO 19115 (MetaData) that provides for 'absolute external accuracy' & 'relative internal accuracy' for positions.
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The Australasian Geodetic Infrastructure
A discussion paper on the future of the geodetic infrastructure in Australia and new Zealand has been prepared for ICSM, to promote discussion on the future form, structure and nature of the geodetic infrastructure - November 2000. This document is in ADOBE PDF format.
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