GDA2020

Implementation

Latest news [10/6/2019]:  Landgate has approved a project for the next financial year (FY19/20) to upgrade its spatial cadastral system (SmartPlan) and database (SCDB) to maintain and deliver its digital cadastre in GDA2020. The upgrade is planned to be delivered by the adoption date of 30 June 2020.  More communication and stakeholder engagement is planned.

ICSM has agreed that 30 June 2020 will be the date by which ANZLIC member agencies in Australian states and territories will be ready to deliver and receive foundation spatial data on the GDA2020 datum [EPSG: 1168]. Refer to the ANZLIC GDA2020 adoption date announcement. We encourage you to start your own implementation. Most software vendors have now implemented the GDA2020 datum and transformation tools. GDA2020 queries that are specific to the implementation by Landgate can be directed to the Landgate - GDA Modernisation Implementation Working Group by email positioning@landgate.wa.gov.au.

Landgate has committed to change its systems and update datasets to take advantage of the new datum. The implementation however, will be completed in stages. Landgate has already upgraded its geodetic database to provide both GDA2020 and GDA94 coordinates and their uncertainty on all geodetic Survey Marks. Geospatial data such as cadastral, imagery, administrative boundaries, road centrelines, topographic, geographic names and more are also available for delivery in GDA2020. To request Landgate's geospatial data use this form or contact our Geospatial team or the Business & Government Solutions Team on +61 (0) 9273 7683 or email BusinessSolutions@landgate.wa.gov.au.

To find out about GDA2020 implications for DataWA or SLIP services contact the Open Data team at opendata@landgate.wa.gov.au.

Transformation products and tools

Coordinate transformation is the process of changing coordinates from one datum (reference frame) to another. There are three options for the transformation of coordinates between GDA94 and GDA2020:

  • 2D conformal NTv2 grid file [EPSG: 8446]
  • 2D conformal + distortion NTv2 grid file [EPSG: 8447]
  • 3D 7 parameter similarity (Helmert) transformation (conformal) [EPSG: 8048]

There are additional 2D conformal only transformation grids for the Indian Ocean Territories:

  • Christmas Island [EPSG: 8444]
  • Cocos (Keeling) Island [EPSG: 8445]

Note: There are no conformal + distortion grids available for the Indian Ocean Territories. Below figure shows the extent of the NTv2 national conformal + distortion transformation grid.

GDA94 to GDA2020 transformation grid extent

Consideration should be given before selection of GDA94-GDA2020 transformation method.

If local geodetic network control marks (SSMs) were used for referencing and/or establishing GDA94 coordinates, localised distortion will need to be taken into account. In this case, the conformal + distortion grid should be used to transform the GDA94 coordinates to GDA2020.

If GDA94 coordinates were observed using Global Navigation Satellite System (GNSS) technology, with corrections coming from a network of GNSS reference stations (CORS), it is likely that the coordinates will be unaffected by local distortions. In this case, the conformal grid or a seven-parameter similarity transformation would be most suitable to transform the GDA94 coordinates to GDA2020.

Consideration for selection of GDA94 - GDA2020 transformation method

Note: Horizontal datum transformation should not affect orthometric height (AHD).

For GDA94-GDA2020 transformation products and tools refer to ICSM website. For detailed description and recommendations refer to the Coordinate Transformation section of the GDA2020 Technical Manual and the ICSM Datum Technical Fact Sheet: TECH Fact sheet 1: GDA94 to GDA2020 transformation.

Recognised-value standard of measurement of position

On 11 October 2017 the National Measurement Institute signed off and gazetted the Geocentric Datum of Australia 2020 (GDA2020) as the new Recognised-Value Standard of Measurement of Position. In effect, GDA2020 is now our new datum and GDA94 has been revoked. Here is a link to the Determination.

Our team, together with other jurisdictions and Geoscience Australia, has developed this new datum that consists of all Landgate’s survey archive data (50+ years) as well as modern GNSS survey data (including data donated by your organisations). Such a large single adjustment has never been done before and it was possible due to the increased computing power as well as innovative methods of computing and data analysis. GDA2020 is free of many of the biases and distortions associated with GDA94 and aligns the datum to the global reference frame in which GNSS natively operate. Fore more information about GDA2020 refer to ISCM website.

Technical manual

For GDA2020 Technical Manual refer to ICSM website.

Metadata

GDA2020 differs by only 1.8 m from GDA94 thus, it is extremely important to provide datum name, and if applicable transformation method, together with the coordinates. Refer to the ANZLIC endorsed national metadata standard AS/NZS ISO 19115-1:2015 and the associated metadata schema ISO/TS 19115-3:2016 for implementation details.

ATRF - Australian Terrestrial Reference Frame

Like GDA94, GDA2020 is fixed to the Australian continent, where coordinates do not change with time. GDA2020 is static reference frame (static datum). However, ICSM has endorsed a plan to introduce a time dependent reference frame called Australian Terrestrial Reference Frame or ATRF. Coordinates in ATRF will change over time as the Australian continent drifts and due to local deformation. ATRF is a time dependent reference frame (dynamic datum). The first realisation of ATRF is called ATRF2014. For more information refer to ICSM website and technical implementation plan.

Important note: Both ATRF and GDA2020 will be supported. GDA2020 will be available for users who do not need a time-dependent reference frame. ATRF is optional and only for users who do need time dependant reference frame and is not intended to be mandatory. GDA2020 and ATRF are compatible and to support different user requirements. The Australian Plate Motion Model can be used to propagate coordinates between GDA2020 and ATRF2014.

Modernising Australian Geospatial Reference System

Official forum supports switch to GDA2020

An online forum has been established by the ICSM to share experiences and find answers relating to questions about the modernisation of Australia's datum. It is moderated by members of the GDA Modernisation Implementation Working Group and other technical specialists from around Australia. More about datum modernisation can be found on GDA Modernisation and Implementation Working Group website.

Geodetic news

Subscribe to this quarterly Geodetic Newsletter to stay up to date with the latest information from Landgate's Survey Services department.

Need help?

For more information contact a member of the Survey Services team on +61 (0)8 9273 7111 or email geodesy@landgate.wa.gov.au.

This page was last updated on: 06 Dec 2019