GDA2020 Transformations & ArcGIS


GDA2020 logo - text under symbolIn my previous articles on GDA2020 I have highlighted some of the considerations that organisations need to have when migrating to the new datum and reasons why Australia is deploying new datum. These I hope have at least prepared you for what’s about to come.

 

In March Geoscience Australia released an interim paper

(http://www.icsm.gov.au/gda2020/InterimReleaseNoteV1.0.pdf)

regarding the definition of GDA2020 and its relationships to GDA94 and the International Terrestrial Reference Frame 2014 (ITRF2014) using similarity transformations. This provided the foundation for including the new datum into the Esri suite of products.

 

 

Shortly Geoscience Australia will release the full definitions for the GDA2020 datum and the NTv2.0 high resolution grid files for the accurate transformations from GDA94 to GDA2020. In preparation for this Esri Australia, Esri and Geoscience Australia have been working together to have the definitions and transformations available in the ArcGIS software suite. Esri is due to release an update for their ArcGIS 10.5.1 and ArcGIS Pro 2.0 suite of products. We anticipate this to be available mid to late June. These will be the first Esri products to include the GDA2020 definitions and transformations.

 

Now due to the closeness of these two releases Esri will not be including the NTv2.0 grid files. However, once Geoscience Australia release the files it will simply be a case of clients downloading the high resolution files from Geoscience Australia at http://www.icsm.gov.au/gda2020/gmiwg.html and placing then in the product directories:

  • ArcGIS Desktop : Program Files (x86)\ArcGIS\Desktop10.5\pedata\ntv2\australia
  • ArcGIS Server: Program Files\ArcGIS\Server\pedata\ntv2\australia
  • ArcGIS Pro: Program Files\ArcGIS\Pro\Resources\pedata\ntv2\australia

Geoscience Australia has provided the expected names of these files

  • For the GDA94 to GDA2020 conformal NTv2 grid, use AUS942020_C.gsb
  • For the GDA94 to GDA2020 NTv2 grid that also includes the full national distortion, use AUS942020_CD.gsb

the transformations will look for files of the correct names. If they do not exist then the software will utilise the lower accuracy similarity transformation.

It is also important to note that the that the NSW Lambert and SA Lambert projections have not yet been defined by the state jurisdictions and so will not be included in this release. Expect these in later releases of ArcGIS software once they have been published.

If you need assistance with upgrading your software, configuring and testing the GDA2020 datum’s or planning your migration please contact your account representative for assistance.

Cheers
Gordon

 

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