New GDA2020 transformations for WebGIS

May 2021

Esri Australia has been working with Esri and ICSM to ensure that the ArcGIS system can support clients migration from the GDA94 static datum to GDA2020 static datum. The ArcGIS system now fully supports data transformations via 7-parameter similarity transformation, or NTv2.0 transformation Grids.

As a result we are now seeing many clients migrate their authoritative datasets to GDA2020 and requiring all delivered data is in this same static datum. State and national governments are now delivering foundational open datasets in GDA2020 as well

In parallel to this migration we are also seeing more clients taking up WebGIS and delivering data via web services instead of shipping datasets or producing PDF’s. This is enabling a greater uptake web and mobile GIS, providing better informed field operators and getting live data in the hands of people who need it as they need it.

These two waves of change have presented a significant challenge. While transformations existed between WGS84 & GDA94 and GDA94 & GDA2020, there existed no direct path from GDA2020 to WGS84. If you wanted to place GDA2020 data into WebGIS you had to transform you data back through GDA94 to WGS84. Effectively moving the data back to its old location prior to publishing. Many clients asked why????

It has been termed the WGS84 Projection dilemma. So what’s changing?

Learn Imagery and Remote Sensing in ArcGIS

Ever wanted to understand how ArcGIS can help you leverage Remotely Sensed Imagery, Drone Imagery, Aerial Imagery and Lidar data datasets. Not sure where to start or how to even get access to dataset to get started with?

Well Esri is investing in the Remote Sensing and Image Analysis. It is now core fundamental components of the ArcGIS System. You will see dynamic imagery and raster analytics soon coming to ArcGIS Online

In order to help with you get started in imagery Esri has release an excellent body of materials that step you through the full end to end workflow of imagery, imagery analysis and result presentation.

Imagery Best Practices

Supporting Imagery and Lidar in the ArcGIS platform has been around for a long time. In the ArcGIS Server Space, Image Server became available at 9.3.1. Since then it has evolved to Mosaic Datasets, Image Services, Raster Functions and now raster analytics. Now imagery is really an integral part of the ArcGIS platform. However, it is only as performant when the imagery is managed and configured optimally.

I often get asked,

• what format should I store my imagery in?,
• How many images can be in a Mosaic Dataset?
• How should I structure my imagery? and
• what is the maximum number of images per folder?

When answering these questions I have drawn on past experience and advice from Esri. Now though Esri have compiled all this information into an Excellent Centralised resource Imagery Workflows – Best Practices https://doc.arcgis.com/en/imagery/workflows/best-practices/what-are-best-practices.htm

In the Imagery formats and Performance section it details topics such as:

• File format suitability
• Recommended imagery formats
• Reformatting imagery
• Pyramids
• Statistics
• Working with large mosaics
• Storage system performance

If you’re going to be managing imagery and lidar I recommend you reads these documents. They are comprehensive and invaluable. I must admit I have been doing this for 12 years now and there is information on Lidar management that I did not know about.

This is just one component of the ArcGIS Imagery Workflows documentation Esri has just produced.

Gordon

ArcGIS 10.2.1 for Utilities supports GDA2020

Esri recently released an update for the ArcGIS 10.2.1 for Utilities and Telecom that has included support for GDA2020 projections and transformations.
The update includes

• support for the mathematical transformation between GDA94 and GDA2020
• Support for the NtV2.0 Grid file transformations
• Also included are the Conformal and Conform + Distortion grid files.

If you intend on migrating to GDA2020 at 10.2.1 then we recommend you update to the latest Patch #9 available from
https://support.esri.com/en/download/7680

Understanding GDA2020 and it’s relationship with Web GIS

NOTE: this was first published Dec 2018 and has been amended in June 2021 to reflect additional software and transformation updates. See note at end of blog.

Background

Australia sits on one of the Earth’s fastest moving tectonic plates which has been moving 70 millimetres per year. By 2020, Australia will have moved 1.8 metres north east of it’s location in 1994. To effectively map the earth, representations, known as datums are used to model and identify locations. Australia’s national datum; Geocentric Datum of Australia 1994 (GDA94) will soon be replaced by a new datum Geodetic Datum of Australia (GDA2020). GDA2020 will align with current positioning technology.

Geoscience Australia and the Intergovernmental Committee on Surveying and Mapping (ICSM) have released a new Geodetic datum GDA2020. The datum provides higher positional accuracy and will be able to represent locations dynamically rather than the stationary GDA94. .

In the coming two to three years most organisations will be transforming their spatial data from the GDA94 datum to the new GDA2020 datum. Esri’s, ArcGIS Software has been updated to accommodate these new datums across Australia and will support all of our customers rigorous requirements for locational and positional accuracy.

Redlining in the ArcGIS Platform

I often get asked about the ability to redline within the ArcGIS Platform.Within the ArcGIS Platform there are essentially 4 options for Redlining as follows:

Site Scan – Esri Edition app provides drone flight planning using your GIS content

Esri business partner 3DR has released a free app for iOS that interfaces with ArcGIS Online, allowing Esri users to view GIS content from ArcGIS Online to assist with the drone flight planning. 

The Site Scan – Esri Edition app provides mission planning and flight control for a number of leading drones to optimize drone collections for use in Drone2Map or Ortho Mapping in ArcGIS Pro.  This release is compatible with the DJI Phantom 4 Pro, DJI M200, DJI M210, DJI Inspire 2, DJI Mavic Pro, or Yuneec H520-G, as well as the 3DR Solo.

The Site Scan – Esri Edition app allows users to take advantage of substantial amounts of publicly accessible data, as well as custom data layers from the user’s ArcGIS Online account, as base and reference data for mission planning.

Site Scan – Esri Edition is free to everyone with an ArcGIS Online account. The app is available on iTunes at http://esriurl.com/SSEE, and will be available soon in the Esri Marketplace.   

 Try it out! 

ArcGIS delivers GDA2020 NTv2 Grid files

With the delivery of ArcGIS Pro 2.2 and ArcGIS 10.6.1 Esri now supports GDA2020 NTv2 grid files out of the box. However, they are not installed with the product. We have had several reports now of customers deploying the latest product and the NTv2 transformations not being available.

Esri Releases Historical Imagery – Wayback

Have you ever looked at the Esri Imagery basemap and wished you could see the changes over time. Esri for a long time has only provided the most recent imagery they have access to for your area of interest.

Well now in the ArcGIS Living Atlas Esri is providing all their historical imagery for your area of interest. Entitled the WayBack Imagery collection Esri providing both an exciting web application World Imagery Wayback which allows you to see the changes in the imagery over time and allows you to select an image and add it to your ArcGIS Online site as well as a Living Atlas group Wayback Imagery group which will allow you to see all the different epochs of  imagery.

Go have a look I’m sure you’ll find it useful.

Gordon

GDA94, GDA2020 and WGS84; The projection dilemma

Progress supporting GDA2020:

The Intergovernmental Committee on Surveying and Mapping (ICSM) & Geoscience Australia (GA) recently released the definitions for the GDA2020 datum and associated projected coordinate systems covering Australia and its territories. Esri Australia has been working closely with ICSM & GA to ensure that ArcGIS software products support the new definitions.  Version 10.6 of ArcGIS and version 2.1 of ArcGIS Pro both include support for the new datum and projected coordinate systems (you can learn more in the Esri Australia Technical Blog)

Avoiding alignment issues mixing datums:

Web GIS, by default, displays data in the projection WGS84 Web Mercator (auxiliary sphere). When mapping data is shared to ‘Web GIS’, data is automatically reprojected ‘on-the-fly’ to this web projection in order to align with the displayed basemap and fit with the global projection. Most users do not realise that their data is being reprojected and in many instances occurs without issue.

However, while organisations are migrating to GDA2020 from GDA94 and using mixed data containing both datums, these mixed data sources will create a challenge when displayed in WGS84. The issue occurs when data is reprojected to the WGS84 Web Mercator projection.