Site transformations: Simple is better

Imagine you had the choice between a high-performance race car, a reliable ute or a DIY jeep that you've cobbled together in your own garage... which one would you pick? Well, the race car may be the height of German engineering, but will probably not be much fun on a 4WD track... you'd want the ute for that. Taking the DIY jeep for a spin on a German autobahn will almost certainly also end in tears. But at least, if it breaks down, you'll know exactly how to fix it! The same principle applies to transformations. There are plenty of options to transform coordinates between different datums or reference frames. Some transformations are very rigorous and use lots of parameters, while others 'cut' corners and use simplifications. The selection of a particular transformation method very much depends on what you want to do with it. In this article, we demonstrate that a simple block shift in Easting, Northing and Height is sufficient to transform Real Time Kinematic (RTK) or Network RTK (NRTK) observations obtained through CORSnet-NSW onto local ground control for surveys requiring centimetre-level accuracy, provided AUSGeoid09 is applied. We analysed an extensive dataset consisting of 2,200 occupations in seven study areas spread out over eastern NSW to come to this conclusion.