Datum Modernisation Updates

In the news

Australia on the move: how GPS keeps up with a continent in constant motion (article in The Conversation).

Datum Modernisation Update 3 May 2017

Work to the enable the change from GDA94 to GDA2020 as Australia’s official national datum is still being finalised. This includes production of the transformation grids, publication of the GDA2020 Technical Manual and the legal adoption of GDA2020 as the Recognized-value standard of measurement of position in Australia. GDA94 remains the national datum until this work is completed.

Datum Modernisation Update March 2017

GDA2020 Interim Release Note

GDA Interim Release Note
GDA2020 Interim Release Note

The Permanent Committee on Geodesy (PCG) has published the GDA2020 Interim Release Note provides information regarding the definition of GDA2020 and its relationships to GDA94 and the International Terrestrial Reference Frame 2014 (ITRF2014) using similarity transformations.

Official Release of GDA2020

The official release of GDA2020 is on track for completion in April 2017. In addition to the definitions and information in the Interim Release Note, this entails the following steps.

  • Issuing a new Legislative Instrument that replaces GDA94 with GDA2020 as the Recognized–Value Standard of Measurement of Position in Australia.
  • Release of the national NTv2 distortion grid to transform between GDA94 and GDA2020 and inclusion in the EPSG registry. The NTv2 grid is the most accurate method to transform between GDA94 and GDA2020.
  • Publication of a new GDA2020 Technical Manual, replacing GDA94 Technical Manual Version 2.4, that will be the “point of truth” about GDA2020 and its relationship to GDA94 and historic Australian datums AGD66 and AGD84. The updated technical manual will provide a modern take of all matters pertaining to geodetic datums in an Australian content. It will include relevant information from the Interim Release Note and supersede that document.

Although the technical manual will be the “point of truth”, ICSM will use a range of mediums to communicate the information to wide variety of audiences. This will include direct communication with software providers, updating ICSM FAQs and Factsheets, and utilising the GDA2020 Forum (see below) and other appropriate forums, such as the Geographic Information Systems Stack Exchange.

GDA2020 Forum now available

In response to the original stakeholder questionnaire, an online forum has been established by ICSM to support users with the implementation of GDA2020. The forum is a place to discuss and share experiences, and find answers to questions relating to the datum modernisation. This includes sector–specific assistance with technical aspects of the change, as well as help for spatial data novices to understand how datums work. It is moderated by members of GMIWG and other technical specialists from around Australia. Please make the effort to register with the forum as its value will be determined by users asking questions. Although at present it is very much a “blank canvas”, GMIWG anticipates it will quickly fill with content once the full release of GDA2020 occurs.

GDA2020 on CORS and Jurisdiction Survey Control

As advised in December 2016, the commercial CORS operators should be providing support for GDA2020 late in 2017. The intention is for providers to support both GDA94 and GDA2020 correction services. Providers will be in touch with their customers, and may use the GDA2020 forum as a means of communicating specific help on this subject.

Each jurisdiction has its own plans for delivering GDA2020 coordinates on permanent survey mark networks in accordance with their projected timeframe for reaching “Operational Capability”. Further information about these timeframes will be provided when it is available, or you can contact your jurisdiction’s GMIWG representative directly.

GDA2020 Operational Capability

As advised in the December 2016 update, it appears that the capability to support GDA2020 will be progressively achieved through 2017 and into early 2018. “Operational capability” is being used to describe this process, rather than an ‘adoption date’.

Each jurisdiction has specific challenges in terms of dataset assessment, transformation and delivery. Nevertheless, all are agreed that by mid–2018, users will be able to either consume data on GDA2020, or access the data they require and transform it themselves using the various transformation tools under development. Some jurisdictions may hold a window for dual Datum data submission, and close that off once monitoring reveals a trend to full GDA2020 adoption by users.

A vital element in achieving operational capability is the inclusion of GDA2020 in spatial software and hardware and GMIWG will inform major software houses and the relevant Open Source Geospatial Foundation projects of its release and inclusion in the EPSG registry.

Transformation and Validation Tools.

A range of tools and services for transforming between GDA94 and GDA2020 will be provided from the ICSM website including a web service for machine to machine requests supporting a variety of data formats and a downloadable executable. These options will utilise the GDA94 to GDA2020 transformation grid.

Work has commenced on amending an existing NTv2 transformation plugin for QGIS to incorporate the NTv2 grids for transforming between AGD66 ⁄ 84 and GDA94. Once the NTv2 grid to transform between GDA94 and GDA2020 is released, this functionality will be added and tested and the plugin publically released. An ICSM branded plugin dealing only with Australian datums is also being developed and will be released around the same time.

These ICSM developed tools will act as a validation service and validation data will also be provided.

Michael Giudici
Chair, GDA Modernisation Implementation Working Group
2nd March 2017