What is the difference between the existing and the new coordinates of a point?
The Australian Geodetic Datum (AGD) was established before satellite techniques were available and was based on a model of the Earth, which was suited to the Australian region as well as could be calculated at the time. GDA94 is based on an international mathematical model which “best fits” the shape of the whole earth, with its centre coinciding with the earth’s centre of mass. Coordinates on the earth’s surface will change approximately 200 metres in a northeasterly direction with the new datum (GDA94). The exact change and orientation of the change will vary from area to area.
