Dynamic cadastre research up and shifting

Having accurate property boundary data underpins the ability for Australian land agencies to protect people’s land rights and titles.

As more information aligns with property boundaries (think utility and environmental data) being certain that information is in its proper location is imperative. This research is the first step in making sure that where your GPS says you are, matches where the data says you should be!

Australia’s tectonic plate is moving 7 cm in a north-eastern direction every year. Most basemaps, such as topographic maps and the cadastre (that’s a map of real estate or property boundaries), are measured against a ‘plate fixed’ coordinate system (or ‘datum’) that moves with the Australian plate. While the plate moves, the coordinates of a feature on the land stay the same. GPS devices on the other hand, use ‘earth fixed’ coordinates, that remain constant in relation to the planet. So, as the plate moves, the GPS coordinates for features on the land change, but their coordinates on our basemaps do not.

By the year 2020, Australia’s current datum (aka ‘GDA94’) will be 1.8 m out of sync with GPS coordinates.

Maurits van der Vlugt, Mercury Project Solutions, says mobile devices with ever-increasing accuracy are becoming ubiquitous. “Soon, there will be millions of personal devices – in phones, autonomous vehicles and drones – with highly accurate GPS-enabled locations,” he said.

“To align basemaps and GPS coordinates, Australia will modernise its datum to ‘GDA2020’,” Maurits continued. “As the name suggests, by 2020 plate-fixed coordinates and GPS coordinates will match!”

However, even with that correction, from 2020 onwards, basemaps and GPS coordinates will be increasingly out of sync at a rate of 7 cm per year. So, what do we do?

“Over the first year, this won’t be such a big problem,” Maurits said. “But as the years pass by, it will be an increasing problem for autonomous vehicles, UAVs, precision agriculture and asset management. We don’t want autonomous farming vehicles to be ploughing the river, or worse, have people dig into a high voltage powerline, because they got the coordinates wrong.

“To fix this issue,” Maurits said, “from 2020 onwards, Australia will also adopt a so-called ‘dynamic datum’, which will align plate-fixed and GPS coordinates, so that they will always match.”

Adrian White from Cadastre NSW, tells us this CRCSI project looks at the impact of introducing a dynamic datum to one of the most fundamental geospatial datasets: the cadastre. “For those that don’t know, the cadastre is a map of the real estate boundaries or the property titles of a country,” he said.

“The cadastre is one of the most critical layers of spatial information held and managed by any jurisdiction. Huge volumes of other spatial and non-spatial information are directly linked to and affected by changes to the cadastral fabric,” Adrian said.

The project will examine how a dynamic datum will impact the acquisition, management and dissemination of cadastral data, and what tasks, tools and procedures would be needed to ensure the adoption will be as smooth and painless as possible.

“If these issues can be resolved for the cadastre, the findings and outputs can be translated into the management of other layers of geospatial information,” Adrian said.

Maurits concluded: “The project will run until June 2018 and will deliver a clear understanding of the impacts of a dynamic datum, the tools and procedures to manage these impacts and a national implementation roadmap.”