Comparison between quoted pin co-ordinates and pin positions, for Initial and Advanced Searches

Gold Tracker

Having completed a considerable number of searches, including those attached, my assessment is that in all cases the system meets all practical requirements, despite some current minor pin placement errors.


It was assumed that the co-ordinates given for the “Mark search point flag”  (black pin) are correct for the pin position on the map. For Zones 50 and 51 I placed the pin at several points for which I had previously obtained hand held GPS co-ordinates.  All the points tested were within a few metres, within the limits of a hand held GPS unit – an excellent result.

I was also able to test returned Initial and Advanced Search co-ordinates, and I am satisfied that they are correct.

Initial and Advanced Searched were performed, and co-ordinates recorded. A “Mark search point flag” was placed close to each search pin.  Zooming in allowed the actual map co-ordinates of the search pin to be estimated to +/- 5 metres.  Co-ordinates were then compared. It was apparent that while the returned co-ordinates were correct, there were some errors in the search pin placement.

Initial searches were conducted near the West side, Centre (Central Meridian) and East side of Zones 50 & 51, similarly, Advanced Searches were conducted at various positions throughout Zones 50, 51 and 52.


EASTINGS: At the central meridian (500,000E) the pin placement error was zero in all cases. The difference increased up to about 40 metres as the edge of the zone was approached, with opposite signs at the common zone boundary. This is not unexpected, and may be due to an approximation in the calculation when converting to the Mercator (UTM) projection.

NORTHINGS: The pin placement error increases from virtually nothing in Northern WA to some 90 metres in the far South.  This may be at least partly due to the same reason.

For each search location, in all cases the error for each Initial search was of the same order as both of the Advanced Searches.

ZONE 52: One test at Halls Creek gave only a few metres error, if any at all.

MY CONCLUSION: As each search result identifies an area within a radius of some 850 metres, the pin positioning errors above are really of no practical significance. These would only show at a large scale anyway. The quoted co-ordinates are correct.

Searches in areas with which I am familiar gave scores that appeared to reflect the expected area prospectivity.


Rod Ebrall
Authorised Mine Surveyor Grade 1 (Retired)

19 January 2015

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