Map Data

Submitted: Thursday, Apr 06, 2006 at 19:34
ThreadID: 32603 Views:2573 Replies:8 FollowUps:17
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I have some points from a archeological survey conducted in 1977- they are UTM typereferences and appear to be the right length for 10 metre accuracy and accompany the map names such as SE55-10. All good.

I know the actual locations of some of these points and others I do not.

The problem is the references are not valid for current day maps. I've looked at the possibility that they may be AMG66 and need converting to either AMG84 or MGA94 datum, but even these conversions do not yield valid locations.

Now I am not a gun with UTM, preferring to work with Lat Long. My question is, could these references be pre-metric ie in feet or yards? If so how can I convert, other than getting old maps?

Dave O
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Reply By: The Explorer - Thursday, Apr 06, 2006 at 19:57

Thursday, Apr 06, 2006 at 19:57
Dave - interesting - they could be in feet or yards...if, as you mention, you know the actual location of some compare the coords that you have with current MGA coords...if the numbers are only about 200metres different then is justs AMG (66 and 84 are only ~3 metres different). If they are wildly different then it suggests yards....but without an example difficult to accertain from here. OziExplorer is good for changing data between datums ...but dont think yards is standard - my have to muck around with a user datum and projection. Can you provide an example coord and map sheet - this will be sufficient for me to determine issue.

Cheers
Greg
I sent one final shout after him to stick to the track, to which he replied “All right,” That was the last ever seen of Gibson - E Giles 23 April 1874

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AnswerID: 165363

Follow Up By: Member - David 0- Thursday, Apr 06, 2006 at 20:08

Thursday, Apr 06, 2006 at 20:08
Greg

I can't provide an example until tomorrow when I can access my office. They are wildly different so I guess it is yards. Will get some examples tomorrow.

Dave O
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Reply By: Graham56 - Thursday, Apr 06, 2006 at 20:04

Thursday, Apr 06, 2006 at 20:04
Hi David,
I'm no gun at mapping but have had some experience, even if itis AGD66 the point would still be relevent if the datum is incorrect it will just be out. is it poosible the point is out by about 200mtr? The only other way I might be able to figure it out would be to see the co ordinates. How many digits in each eastings and northings?
Regards Graham
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Follow Up By: Member - David 0- Thursday, Apr 06, 2006 at 20:11

Thursday, Apr 06, 2006 at 20:11
Graham

The point is out by more than 200 metres, some appear to not be on the map at all. I don't have them with me but if I recall correctly they were 6 digit, if so thats 100m not 10 as I first said isn't it?

Dave O
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Reply By: Gaz31 - Thursday, Apr 06, 2006 at 21:47

Thursday, Apr 06, 2006 at 21:47
Hi Dave,
you say that you have some points that you know in both systems while some of them you don't. In excel work out the difference in Northings and Eastings between the common points and then apply the difference to your funny coordinates.

ie old northing = 1000mN old Easting 5000mE
new northing 1000mN and new easting 7000mE
the adjustment from old to new will be +9000mN to all the old northings and +2000mE to the old easting.
give that a shot.
AnswerID: 165408

Follow Up By: Member- Rox (WA) - Thursday, Apr 06, 2006 at 23:34

Thursday, Apr 06, 2006 at 23:34
You may have left out 1 "0"

"ie old northing = 1000mN
new northing 1000mN"

Doesn't add up to " +9000mN" to me but It is a guess to me.
Just looking at the maths.
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Reply By:- Friday, Apr 07, 2006 at 07:23

Friday, Apr 07, 2006 at 07:23
OK

Here are a couple

Map SE5514 1:250000
References given is 483364
and 487374

Both are meant to be on Mt Louisa

Some others

SE5514
References 485593 and 486394
Both are meant to be on the Many Peaks Range

I can't figure it out
AnswerID: 165461

Follow Up By: agsmky - Friday, Apr 07, 2006 at 08:13

Friday, Apr 07, 2006 at 08:13
Coordinates don't add up.....it doesn't look like any AGD/GDA (~200m) error, more than likely this is an issue with the Datum format.

For your reference the (full) UTM coordinates (using AGD66) for Mt Louisa (very close to the top) is:

55k 472843E 7868132N

As can be seen, the numbers do not line up. If these coordinates were just a simple 6 figure grid reference (or part of the MGRS system), the numbers would be more like 728 681 (space included for neatness).

BTW maybe you could inform us of the origin of these coordinates (where they were obtained from) as it may help work out what they mean. At the end of the day, these "coordinates" may just be meters East and meters N (the last 3 digits of the full UTM coordinates respectively) as this may be all that was required to reference the location at that time.

Hope this helps

Andrew
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Reply By:- Friday, Apr 07, 2006 at 08:31

Friday, Apr 07, 2006 at 08:31
Something wrong with my access to the forum, so can't post as a follow-up

Andrew

That is the conclusion I came to.
The co-ordinates came from a Thesis by an archeology PhD student from the 1970's, they just appear as six figure numbers with a map name like SE5510 in a table of data about specific locations.

Dave O
AnswerID: 165491

Follow Up By: agsmky - Friday, Apr 07, 2006 at 08:50

Friday, Apr 07, 2006 at 08:50
And this person passed!!!

Dave, do you any idea of where exactly any of these coordinates are suppose to be. If you have any accurate coordinates plus the corresponding "unknown coordinate format" someone may be able to correlate the two.

There is always the possibility that the student knew more about Archeology than Geodesy ;-)

Andrew
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Reply By: Bob Creasy - Friday, Apr 07, 2006 at 09:11

Friday, Apr 07, 2006 at 09:11
Andrew might be right a milatary system I have old Geo maps with co-ords in yards
try
Bob
AnswerID: 165506

Reply By: agsmky - Friday, Apr 07, 2006 at 09:57

Friday, Apr 07, 2006 at 09:57
Dave,

The coordinates might be using the Clarke 1858 spheroid as explained in www.ga.gov.au/geodesy/datums/ang.jsp

If the coordinates were taken from a map at the time (more than likely) then unless you have access to the map in question, the numbers may mean nothing.

You may not be able to convert easily......

Andrew
AnswerID: 165514

Follow Up By: agsmky - Friday, Apr 07, 2006 at 10:14

Friday, Apr 07, 2006 at 10:14
just to add....

Checked through the list of mapping i have of this area, and it may be referenced from the 1:250000 geology map, printed in 1968. This can be found at http://www.geoscience.gov.au/geol250k/250dpi/se5514.jpg (9.14mb). The rest of these geology maps can be downloaded at Site Link . After all, archeology is almost spelt the same as geology ;-)

After reviewing the coordinates, there is still some strange things happening.

Andrew
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Follow Up By: David from David and Justine Olsen's 4WD Tag-Along - Friday, Apr 07, 2006 at 13:54

Friday, Apr 07, 2006 at 13:54
Andrew

Thanks, that link will be very helpful

Dave O
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FollowupID: 420444

Reply By: The Explorer - Friday, Apr 07, 2006 at 12:01

Friday, Apr 07, 2006 at 12:01
Hello - I think I have figured it out - the numbers given are yards using the universal Grid system (sometimes referred to the military grid system) or a version thereof.

And as far as I can figure there is also a mistake with your transcription (or someone’s) of the coords – you are reading some of the 5’s as 3’s (and hence the addition confusion created). If 3's are use the coords plot way out. Are the coords you have handwritten?

Ok in the examples you have given
Mt Louisa area
SE5514
References given is 483364 and 487374

These should be 483564 and 487574 (ie some 5’s have been misread as 3’s)

483564 represents 483000 yards East and 2564000 yards North
487574 represents 487000 yards East and 2574000 yards North

These don’t actually plot on Mt Louisa but along a river just south of it?? Mt Loiusa is actually at about 483583…so maybe I have got this all wrong….

Many Peaks Range
SE5514
References 485593 and 486394
The first one 485593 is right but the second should be 486594

485593 represents 485000 yards East and 2593000 yards North
486594 represents 486000 yards East and 2594000 yards North

These plot on the Many Peaks Range…so these look OK

I have taken these coords from the 250k Geology Map of the area using OziExplorer (I have all of Australia at 250K calibrated). This is the easiest way to convert the coords to something useable..unless you actually have a paper copy of the map which would also be handy. I do not know of a calculation that does the conversion. Also not all the Geology maps are “out of date” with yards shown and therefore useful for this purpose..but you may be lucky.

Anyway hope I have headed you down the right path.

Cheers
Greg
I sent one final shout after him to stick to the track, to which he replied “All right,” That was the last ever seen of Gibson - E Giles 23 April 1874

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AnswerID: 165558

Follow Up By: David from David and Justine Olsen's 4WD Tag-Along - Friday, Apr 07, 2006 at 13:30

Friday, Apr 07, 2006 at 13:30
Greg

You are a champion. The fonnt used is very small and flamboyant making 3's difficult to distinguish from 5's.

Do you have the Lat Lon for the positions you calculated? That would help me to see the magnitude of the problem.

Yes I suspect the Mt Louisa sites are on the bottom of the southern slope.

The maps I have are Natmap 250K in Oziexplorer.

If you are ever up in Townsville, drop in I'll give you a freebie tour of some interesting places.

Dave O

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Follow Up By: Member - Willie , Epping .Syd. - Friday, Apr 07, 2006 at 15:17

Friday, Apr 07, 2006 at 15:17
I agree Greg ,
Your a legend .
Willie .
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Follow Up By: The Explorer - Saturday, Apr 08, 2006 at 09:51

Saturday, Apr 08, 2006 at 09:51
David sorry for late reply - Ok converting as best I can the grids references you have supplied I get the following -
Many Peaks - these plot nicely on the Many Peaks area so looks like we've got this right

485593 = 19° 11' 58.169" S 146° 44' 23.855"E
486594 = 19° 11' 28.380" S 146° 44' 55.221"E

Mt Louisa - I am not happy with these - they plot well south of Mt Loiusa (one near Mt Stuart and one near the dam) ..even when changing the 3's to 5's...so maybe there is something else wrong? Anyway..

487574 = 19° 21' 25.079"S 146° 45' 29.393"E
483564 =19° 26' 22.908"S 146° 43' 23.802"E

If I change some other numbers so they plot over Mt Loiusa in an orientation similar to the Many Peaks transect I get this...

483584 = 19° 16' 26.208"S 146° 43' 20.252"E
487584 = 19° 16' 26.178"S 146° 45' 25.717"E

but thats just a guess and may be completely wrong

Keep in mind the accuracy of these grid references - they are only to the nearest 1000 yards (914.4metres) which is pretty rough. I assume the report in question also has site descriptions (maybe photos?) which will help in narrowing down the location of the transects.

Cheers
Greg

PS I think my brother inlaw lives in Townsville - he has a Landcruiser with ALL4PLAY on the number plate - seen him around?
I sent one final shout after him to stick to the track, to which he replied “All right,” That was the last ever seen of Gibson - E Giles 23 April 1874

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My Profile  My Blog  My Position  Send Message
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Follow Up By: David from David and Justine Olsen's 4WD Tag-Along - Saturday, Apr 08, 2006 at 09:58

Saturday, Apr 08, 2006 at 09:58
Thanks so much for that. The Mt Louisa sites have me beat until I can recheck the original document. Unfortunately no photos of those.

I have never seen the plate you mentioned but I will definitley keep an eye out for it now.

Cheers
David
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