Although Australia’s datum modernisation program has been in discussion for the last few years, it was the ABC interview with Geoscience Australia‘s Dan Jaska that ignited the media frenzy and brought GDA2020 to the public’s attention.
“The idea that Australia’s latitudes and longitudes are ‘out by 1.5 metres’ is bound to grab attention,” said Michael Giudici of the Intergovernmental Committee on Surveying and Mapping (ICSM), the body responsible for implementing the change.
“It sounds like a problem, and doesn’t seem to make sense in this modern age,” Giudici said, who is also the Surveyor General in Tasmania.
“Even the explanation challenges our learned understanding that locations on the Earth are uniquely defined by one latitude and one longitude,” he said.
“This is the key concept that we have to debunk to help stakeholders appreciate why we are modernising the Geocentric Datum of Australia 1994 (GDA94).”
Giudici said it was encouraging to see broad recognition that many new technologies rely on global navigation satellite systems (GNSS) such as GPS, and that all Australians would benefit from the modernised national datum. There was also a developing understanding of the widening discrepancy between physically-mapped and GPS-measured locations.
As an example, an article by Atlas Obscura explained that satellite navigation doesn’t update ‘maps’ as the tectonic plates move.
“Australia’s plate-fixed GDA94 datum has, until now, met the needs of users of location information,” Mr Giudici said.
“Professionals have been able to utilise accurate location information because they have the capability to relate measured locations to mapped features on the plate-fixed datum.
“But within a few years, a vast range of consumer devices will measure locations with accuracies of 10 centimetres, based on GNSS locations determined in the globally standardised ‘Earth-fixed’ International Terrestrial Reference Frame.
This change in technology won’t be gradual.” – Michael Guidici
“As is typical of the digital age, the number of devices using accurate GNSS will explode virtually overnight.
“We’re addressing the issue for Australians by bringing GPS locations measured in real time into line with feature locations mapped on our national datum.
“This means the majority of users of GNSS and location information won’t need to take any direct action.”
The datum modernisation will take place in two stages to allow for the complexity of changing the supporting data management systems.
At the start of 2017 a new plate-fixed datum, GDA2020, will be introduced. This datum will shift latitude and longitude locations by approximately 1.8 metres. In effect, the location of features mapped on the national datum will closely align with GNSS locations in 2020.
In 2020, a new kind of national location reference system that allows for locations of points and their movement over time to be modelled will be put in place, keeping Australia up to date with the requirements of all GNSS based technology.
The ICSM GDA Modernisation Implementation Working Group (GMIWG) has recently provided information updates for stakeholders. The key points below are detailed on the group’s website:
- Direct engagement with commercial off-the-shelf (COTS) software providers by Geoscience Australia is planned in order to minimise the time period required for new datum definitions and transformations to make their way into COTS software.
- The imminent release of an ISO ‘certified’ geodetic register this year will assist in the application of ‘official’ transformation parameters between datums.
- A recent international commitment, strongly supported by Australia and New Zealand, to revise the ISO/TC 211 standards framework before 2020 to allow for time-dependant reference frames should alleviate concerns about the technical implementation of Stage 2 of the datum modernisation.