gallet Posted February 7, 2008 Posted February 7, 2008 (edited) I was just checking my UTM datums against a paper topo map before venturing out into the Wild Dog Mountains. My paper maps use the GDA datum (geodetic datum australia) and when I cross checked it against the default datum for DD.DDDDº which is WGS84, I find that the UTM coordinates are *exactly* the same. Why? I tried some other australian datums like ausgeod84 and it was out by a bit. How is it that the GDA out of all the dozens of datums is exactly the same as WGS84? Does this mean that I can safely leave my datum at WGS when using my australian topo maps? (It's a lot easier than scolling the datum list everytime I change from DD.DDDD to UTM) To put my question another way...why is WGS84 the same as GDA? Edited February 7, 2008 by gallet Quote
+bargle Posted February 7, 2008 Posted February 7, 2008 To put my question another way...why is WGS84 the same as GDA? This is the best explanation that I've found: http://www.cage.curtin.edu.au/~will/datum.html To make a long story short, WGS84 has been adjusted to the IERS's (International Earth Rotation Service's) Terrestrial Reference Frame (ITRF), and GDA is based on the ITRF. So, they are compatible and it seems you should be able to use them interchangeably, for now. Quote
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