OziExplorer and Raster Chart Datums
Submitted: Tuesday, Jun 20, 2006 at 11:42
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Member - Pedro the One (QLD)
Hi ... have just come across a problem with datums new to me.
Some of my current Raster 250K maps USING OziExplorer show datum as GDA 94 [1994] and my GPS [Lowrance Map 100] utilises standard WGS 84.
The Raster map data advises that the HORIZONTAL Datum IS EQUIVALENT TO WGS 84. Taking a known point on both maps, there are minor differences in 'points of a minute' positioning.
QUESTION....... does this mean that WGS 84 and GDA 94 are equally accurate in my reckonings ......... bearing in mind the comment above " IS EQUIVALENT TO!"
Am currently using this info to locate/identify potential gold bearing locations, for detecting,thusly accuracy is fairly important to me.
Or does this mean that a more up-to-date GPS is called for?
And no ...... if I tell you any specifics on the said locations, I will have to kill you !!!
There must be a few members in this field, with the neccessary skills/knowledge.
Reply By: Member - Jay Gee (WA) - Tuesday, Jun 20, 2006 at 12:59
Tuesday, Jun 20, 2006 at 12:59
I went through the exercise about 2 years ago of trying to work out "what is the practical difference - if any - between WGS84 and GDA94?". After reading mountains of websites the only conclusions I could come to was:
(1) Yes there is a difference
(2) The difference is in the order of about 8 cm
(3) The average GPS is about 16 cm long - the difference is less than the size of your GPS.
(4) The difference is far less than the accuracy of an average GPS.
(5) The difference is even less than the accuracy of a differential GPS (accuracy 1m)
Therefore - for practical purposes - there isn't any real difference
Jeff
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