AMG maps - cant calibrate correctly ? Advise/help please ?

Questions and problems regarding map calibration and conversion.

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AMG maps - cant calibrate correctly ? Advise/help please ?

Postby TerryF » Wed Jul 27, 2005 12:41 pm

I have a map of an area of Sydney Australia that Ive scanned which has AMG coordinates of the form 6280000mN, 292000mE in zone 56.

I also have some known POINTS from a public GPS database Ive loaded in.

In the MAP manager Im unsure how to correctly calibrate the map. Its clearly not a simple matter of using a rectangular calibration type with a datum of AMG66 or AMG84, which this map presumably uses. (I calibrated using 4 known points, which were grid intersection points off the map).

When I view this in Pathaway, the known points appear suspiciously to the east of the correct point. Of course I was expecting them to coincide with the correct physical location (which I also know on the map).

Also centring on known grid points on the visible grid lines gives incorrect grid references according to what the hardcopy map says, unless those points are the corners of the map.

Having done some reading I now suspect I need to use a PROJECTION calibration, probably with AMG66 datam and a transverse mercator projection. However I have no idea what the projection parameters are for, nor what I should set them to - in fact clearly Im fairly new to all this !

Im hoping someone has been there and done that before - am I on the right track ? What setup should I use in Map Manager to get the map correctly coordinated ?

Any help would be greatly appreciated.


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Joined: Thu Jan 04, 2007 6:10 am

Postby dg » Mon Jan 08, 2007 12:49 pm

I agree there is definitely a problem here.

I tried to register a 1:250000 map sheet using 2 points, TL BR, MGA datum, lat longs. GPS point plotted about 20km east of the correct map position. I recalibrated the TL and BR in the handheld, this time using UTM grid coordinates. That fixed the problem, GPS point plotted where it should on the map.

I would also like to look at the "Advanced Mapping Manual" mentioned on page 70 of the PathAway manual. Anyone know where this is hiden?? None of the hotlinks in the manual work, also it is not bookmarked.

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Joined: Fri Dec 01, 2006 1:39 pm

Postby xombul » Mon Jan 15, 2007 7:23 pm

I googled for [pathaway "Advanced Mapping Manual"] and came with this:
I don't know if it helps (it didn't help me, but what I was looking for was not about projections).

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