Tectonic shifts: news on datum modernisation from #Locate19

By on 24 April, 2019

Three gurus of geodesy presented a comprehensive, practical session on the newest changes to Australian datums — and how to use them.

Captained by Tasmania’s Surveyor-General Michael Giudici, NSW Spatial Services’ Joel Haasdyk and Geoscience Australia’s Nicholas Brown, the datum modernisation session at #Locate19 was packed with hands-on, take-home advice for those working with datum in any capacity.

The presentations featured detailed updates on the implementation of GDA2020 and upgrades to the Australian Geospatial Reference System, coupled with practical advice for individuals and organisations, who may be at different stages in their transition.

Tasmania’s Surveyor-General Michael Giudici kicked off the presentations with an overview and background to the changes, valuable context around the upgrades to Australia’s positioning capability planned for the coming decade, in the form of space- and ground-based GNSS augmentation systems.

Giudici’s presentation focused around the issue of the web mercator dilemma — the issue of the WGS84 ‘hub’ and its ubiquity in the online mapping world, which has led to the deprecation of the EPSG code defining transformation parameters between WGS84 and GDA94.

The answer to this problem, which calls for dramatic improvements to coordinate transformations and systems for a range of GIS software and open source libraries — is a coordinated international effort, for which target funding was reached in May 2018.

On the back of the international effort, the ICSM has engaged North Road Pty Ltd to undertake the work program for the Australian effort, a project being managed by Mercury Project Solutions.

A key date highlighted by Giudici was June 30, 2020 — the date by which ANZLIC member agencies in Australian states and territories have committed to be ready to deliver and receive foundation spatial data on the GDA2020 datum. Mark your calendars, folks.

ICSM have engaged Michael Barwick from Geoscience Australia to manage review of the existing implementation plan, and GA have made communications officer Kathryn Owens available for ongoing datum and positioning communications.

Joel Haasdyk, program manager for the NSW implementation for GDA2020 was up next, with a punchy presentation outlining and explaining the key phases in the program.

2018 saw the preparation phase, while the enabling phase is in full swing in 2019, and the adoption phase beginning from Jan 1 2020, at which point we can expect to see registered survey plans on GDA2020.

Key messages from Haasdyk’s practically-focused talk included emphasising the support for both GDA94 and GDA2020 throughout the projected implementation, to support entities at all stages of the transition to GDA2020.

Walking through the circumstances in which particular tools should be used, such as the time-dependent Australian Terrestrial Reference Frame’s nature in accounting for plate motion and deformation, and circumstances in which AUSGeoid2020 should be used to calculate heights were noted carefully by the assembled crowd.

The static nature of GDA2020 was emphasised, and an illuminating background to the drivers necessitating the updates to datum, and the national adjustment process using the Plate Motion Model were outlined, followed up by hands-on illustrations of how to utilise these new products in a GIS or surveying workflow.

The portion of Mr. Haasdyk’s talk on ‘on-the-fly’ transformation from GDA94 to GDA2020 in QGIS and Esri workflows was of particular value, as was walking through the online transformation service and accessing the NTv2 transformation grids.

Rounding out the presentation were a rundown of the data infrastructure to support both GDA94 and GDA2020-based workflows, and a detailed breakdown of NSW’s adoption timeline.

Nick Brown took the podium for the final presentation of the session, a detailed analysis of the recent and impending changes to the Australian Geospatial Reference System, in preparation for national positioning accuracy of 5 to 10 centimetres.

Brown led by defining the needs for updating datums, infrastructure, models and standards by outlining key initiatives and developments that will rely on it, colossal in scope: Cadastre 2034, the 2026Agenda, Digital Earth Australia, the national positioning infrastructure and rapid uptake of BIM and Internet of Things initiatives.

The core message was that this massive program of upgrades was needed to meet the emerging needs of new users across a wide array of verticals — the uptake of geodetic data products is no longer a niche need.

Drilling down into those needs was fascinating. Emerging markets such as the autonomous transport space and contemporary location-based service demand real-time, high precision positioning services aligned to a global, time-dependent reference frame — such as those in which GNSS services operate.

In a survey of 170 respondents of height reference frame users, 70 percent needed absolute accuracy better than 5 centimetres, and 50 percent needed relative accuracy better than one centimetre.

Based on these results, a critical note is that this level of accuracy is not achievable with AUSGeoid2020, which is only capable of 6-13 centimetre accuracy — a new Australian Vertical Working Service must be employed for greater vertical accuracy, which can deliver 1-8 centimetres.

A final walkthrough on how Australian datums interact rounded out a heavyweight, pragmatic afternoon that demonstrated the rapidly increasing importance of highly accurate datums to a range of future industries — and that it is a field that Australia is becoming an emerging leader within.

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