SPATIAL & GIS
UPGRADING
GEOSPATIAL REF While global positioning systems (GPS) can currently provide 5-10m accuracy, more precise positioning is increasingly important for applications in civil engineering, construction, disaster response, flood and storm modelling, and more. Here, Nicholas Brown, Director of National Geodesy at Geoscience Australia, talks about the $225 million Positioning Australia program, and upgrades to the Australian Geospatial Reference System.
A
ccording to Mr Brown, the majority of growth in Global Navigation Satellite System (GNSS) sales is within emerging markets such as locationbased services, intelligent transport and Internet of Things (IoT) devices. The Positioning Australia program will provide accurate and reliable positioning for everyone. The aim is to accelerate the adoption and development of location-based technology and applications. “In anticipation for the growing use and reliance on precise positioning technology, the Permanent Committee on Geodesy is leading the upgrade of a number of elements of Australia’s Geospatial Reference System including the static datum, the introduction of a time-dependent reference frame, improved geodetic infrastructure, and standards development to improve access and efficiency of geodetic data,” Mr Brown said.
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March 2020 // Issue 14
The introduction of the Australian Terrestrial Reference Frame (ATRF) and the Australian Vertical Working Surface (AVWS) from 1 January 2020 will have a significant impact on the delivery of projects and operations involving precise spatial and positional data, improving accuracy, efficiency and safety.
AUSTRALIAN TERRESTRIAL REFERENCE FRAME The Geocentric Datum of Australia 2020 (GDA2020) is a static datum, which means that the coordinates of features (e.g. roads, buildings and property boundaries), do not change with time despite the ongoing changes in the Earth’s surface. This is beneficial for applications where it is easier if the coordinates of features do not change (e.g. a major road development project). In contrast, GNSS base their coordinates on a framework that is fixed to the centre of the earth around which satellites are orbiting.
These frameworks are called ‘timedependent reference frames’ in which the positions of features change with time due to plate tectonic motion. The ATRF is a time-dependent reference frame that means the positions of features will change with time due to plate tectonic motion, which equates to approximately 7cm per year in Australia. “Users of ATRF are expected to be predominantly from the areas of intelligent transport services and location-based services,” Mr Brown explained. For example, in the future, driverless cars will be receiving positioning information from GNSS satellites in ATRF and cars will be automatically requesting and receiving updated map information in ATRF to align with the car’s position.” In 2020, Australia will adopt this two-frame approach, enabling users to work with a static datum, GDA2020, or with the ATRF.
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