Bushwalk Australia

Gday,

I have some historical data I need to use and unfortunately its been stored with a six digit grid reference and map sheet name. I need to convert this to lat/lon. The conversion part is ok (ish) however I need to construct the full UTM grid reference before I convert it to lat/lon.

I need a resource that matched map sheet name to UTM Grid: Otford 9219 4S -> 56H 3 XX XXX 62 XX XXX
I still havent quite figured out what happens when the sheet crosses the 99->00 border but anything to start me off is a great help.

Does anyone know if such a resource exists?

Does this help at all? Is it even in the right area?

https://mapstore.avenza.com/public/182769/

No sorry I should be more clear. I have about 5000 six digit grid references all over NSW. I also have the map sheet names for those GRs. I need to build the full GR from those two things.

OK thats a bit harder. I will see what I can find. I assume they are only the NSW 1:25000 maps or could they be referring to other map scales as well??

we can also assume the coordinates are not in GDA either? AGD66 perhaps?

Yep that's a good start. I have locations in Vic too but will do nsw first. Cheers

Gda

send me some sample points and I will see what I can do

If you can open the data in excel, you should be able to make them using VLookup and nifty cell programming.

There is a mathematical relationship between the map numbers and lat lon.
Sheet numbers at 1:100 000 scale are four digit numbers. The first two digits define a longitude band 0.5 degree wide and the second two digits a latitude band 0.5 degree wide.
The calculation is quite complex. E.g.
The centre of the 100k sheet 8325 is:
Lat = 25 * 0.5 + 0.25 - 49
Lon = 83 * 0.5 + 0.25 + 105.5
You can calculate the lat lon of the centre of the 25k sheet from this and also the edges by adding/subtracting the appropriate amount. You would have to convert the lat lon to GDA grid references.
It's not trivial, but possible. I don't know if this is enough to get you started.

That's perfect. But also complicated as are all things map related. Thanks a million.

Any luck yet? I am just curious how you are going?

Work in progress. It will take some time. I'm having trouble with some freely available converters in excel. I have three downloaded and they all give different results! The one from geoscience Australia works correctly but is a single conversion. The batch ones I have found not work for the southern hemisphere... Or at least they put a point some 15km from where it should have been. I'll be disassembling the GA spreadsheet and making a batch converter from it. That seems to be the best oath for my initial requirements. This is only a side project at the moment and i have a field assignment for the next two weeks.

Public service announcement... The converter I found here http://www.uwgb.edu/dutchs/usefuldata/utmformulas.htm worked for the one off conversion but the batch converter did not work. If you can debug it please let me know.

so have you manged to go from 6 figure refs to full 6/7 figure refs?

Hi cnschulz,

If you're comfortable using command line and scripting, knocking up a script to convert lat/lon to WGS84 (or vice versa) in perl would be pretty trivial.
See http://search.cpan.org/~grahamc/Geo-Coordinates-UTM-0.09/UTM.pm. This module does all the work.
Of course you'd need to install perl. ActivePerl is best for Windows. http://www.activestate.com/activeperl.

If you send me the utm data I'll convert it to lat/lon.

DELETED

The Steven Dutch spreadsheet seems to work for batch conversion from UTM to Lat/Lon. You have to manually enter the centre longitude of the UTM zone in col E. Eg Zone 55 has a Central Meridian = 147. You can get 55 >> 147 from the Main page. (Also put S in col D). Have you found a list to get UTM zones for each of your map names?
You can insert a new sheet in the GA spreadsheet then copy-paste all your UTM data to it, then record an Excel macro to get a single Lat/Lon from a single UTM coord. Then assign it to a single keystroke, or make a Do-Loop or For-Next loop for the macro to convert all UTM coords. Open the GA SS and insert a new sheet called 'MyData'. Copy all your Zone nos, Eastings and Northings into Cols A, B, C, respectively. Select the first cell with the first Zone number in it. Select the Zone cell (E3) in sheet 'E,N Zne to Latitude & Longitude'. Then select the sheet 'MyData'. Record a new macro (View - Macros - Record Macro. Click Use Relative References). Give it a name, and select a key for Shortcut Key (eg l). Then copy-paste Zone, Easting and Northing from the sheet 'MyData' to sheet 'E,N Zne to Latitude & Longitude' cells E3, E4 and O4 respectively. Then select the Lat and Lon data in cells C43:E43 and M43:O43 and copy-paste_values the Lat Lon data into sheet 'MyData' beside the UTM data. Then select the Zone cell (E3) in sheet 'E,N Zne to Latitude & Longitude' and select Col A in the next row in Sheet 'MyData'. Then Stop Recording (View - Macros). Then each time you press Ctrl-l, another UTM is converted to Lat/Lon. Open the Macro Editor (View - Macros - View Macro - Edit), and put a For-Next loop around the macro, to do all at once (eg For i = 1 to 5000, or how many you have).

I have the OziExplorer .map image calibration files for the OziExp NSW 25000 maps. I think these files are available for free on the OziExp website. There is one .map file for each map image. I have 771 .map files. Each file contains the map name and the lat/lon of the top-left and bottom-right corners. I can make a single file with all this data in it, if you want, using a simple VBScript or Excel macro. The Lat/Lons could then be converted into UTM coords, using the Steven Dutch spreadsheet, or the GA spreadsheet with the macro, above. Then you have a list of the UTM bounds of the 771 maps. Let me know if you want the file.

The hardest part is conversion of 6 figure GRs to full UTM GRs. Ken's suggestion of generating bounds off the maps is a good starting point. You'd then have to write an algorithm to use that info to convert the 6 figure GRs. Tricky (much easier going the other way!!)

I have a JS & XLSX file with the NSW map bounds at http://maps.ozultimate.com/wiki/downloads - it's what I use to produce the Map/6 figure reference at http://maps.ozultimate.com/

I have converted the bounds for all 771 25k NSW topos into UTM. As the 25k maps don't cover the whole state I have done the 100k maps as well.

The forum software wont let me upload csv files and I tried changing the file extension but it still throws errors. I understand this is to protect the forum users from virus type attacks, fair enough. If people want the data, PM me an email address and I am happy to email the files.

Here is some sample data from the 25k csv file (100k file is same format):
Map Number,Map Name,Min Lat,Max Lat,Min Long,Max Long,UTM min easting,UTM max easting,UTM min northing,UTM max northing,UTM zone
81281N,LEETON,-34.500,-34.625,146.250,146.500,431146,454166,6168428,6182147,55H
81281S,EUROLEY,-34.625,-34.750,146.250,146.500,431249,454235,6154566,6168286,55H
81284N,WHITTON,-34.500,-34.625,146.000,146.250,408195,431249,6168286,6181948,55H
81284S,TUBBO,-34.625,-34.750,146.000,146.250,408332,431353,6154424,6168087,55H

I have done the data extracting and massaging with Linux shell scripts and used the hampstermap.com website for the actual utm conversion. I am pretty confident that I have done this correctly but if anyone finds errors please let me know.

Cheers,
Michael.

P.S. When I get time I will have a look at converting 6 digit UTMs to proper format. I might be able to do this with AWK...thinking....thinking...

Gday Michael (and others who are listening)

Thank you very much for your bounding rectangle data. It has literally saved me days of work. Id did have a little problem that took me a while to work out,,,

The data supplied is the minimum bounding rectangle of each map. ie, the smallest grid north rectangle that fits the entire map extent in to it. The problem is that the actual rectangle of the extent of the map is not grid north. In simple terms, the left hand side bottom of the map has a lower grid reference than the right.

Its good enough for what i need right now, but soon ill need to make shape files from this data so i can tell which maps sheet a particular location is on.

Do you (or anyone) know of how I can get/make the data I need?

QGIS will make shape files from many other formats. It will also import from CSV files all your points and then convert them to many other datums/projections - all open source and free. I suspect GPSBabel would also do the job.

Yep understood. That's not the main concern though. The data supplied was the MBR for the map extent. Not the map extent itself. Maps are printed TN not GN.

My OziExplorer .map files have Lon and Lat for each of the 4 corners of each .map file. It looks like this in the file:

MMPXY,1,0,0
MMPXY,2,5120,0
MMPXY,3,5120,2560
MMPXY,4,0,2560
MMPLL,1, 151.000000, -34.125000
MMPLL,2, 151.250000, -34.125000
MMPLL,3, 151.250000, -34.250000
MMPLL,4, 151.000000, -34.250000

I dont know if the OziExp maps that I have are the same as the maps you have. They look 'digital'. Here is a screenshot of the top left corner of the 91294S__OTFORD 25k map. The Lon/Lats can be converted to GDA. I dont know if these are the same .map files as Michael's. I can make a single file with the Lat/Lons and GDA's of each of the 4 corners if you want. Michael probably can too. Did you contact him?

PS - What happens when one side of the map is in a different Zone to the other side? What Zone does the map grid use? Is there a convention?

PPS - This only happens at 150 deg Lon (and 144 deg, if there are NSW maps for that Lon). The 150 deg Lon is the eastern bound of one map and the western bound of the adjacent map. Ie a tiny overlap. So the correct Zone is the Zone associated with the Western bound of the maps. To get the correct eastern UTM bound of those maps, a Lon of less than 150 deg must be used. Eg 149.999999 (approx 1 metre less than 150 deg).

Ken

cnschulz wrote:Do you (or anyone) know of how I can get/make the data I need?

For actual map extents, you can't use UTM.

They are defined by Lat/Lon bounds.

That shouldn't be an issue for your conversion. You can use the MBR as a proxy. It will be sufficiently accurate to uniquely locate a 6 figure GR.

I've make an Excel Spreadsheet (2010 version) that converts 6 digit GDA references to Lat/Lon. It uses the Geosciences Aust spreadsheet and the NSW 25000 scale map bounds, in Lat Lon from 'maps.ozultimate.com/wiki/downloads'. I made a copy of the GA SS and recorded 2 macros into it. One for converting the map corners from Lat/Lon to GDA, and the other to convert the full gda references from GDA to Lat/Lon. The full references are generated by VLOOKUP() and other formulas.The VLOOKUP() formulas use the map number. That can be changed to Map name, if thats what you have. I've only tested it with a few 6 digit refs. And not fully. If you send me some more test data, I'll check it more thoroughly. let me know if you find any bugs in it! The 6 digit refs and map name and number are pasted into sheet 'Conv 6 digit grid'. Instructions are in sheet 'Notes'. The macros run slowly. You can set it to run batches of numbers by editing the For-Next loop. Start the macro on the Zone cell of the next row of data to convert.
You can download it from Google Drive at:
https://drive.google.com/open?id=0B6Dis ... TFqQUt3ZkE
Ken

Gday, I now have a solution for converting utm 6 digit to full gr and then to lat long. I also have a "proper" spreadsheet and shape file for the map bounds. Thanks everyone for your help especially tastrax and Michael_p. Cheers

Too funny, Ken! I did much the same thing - but I stopped at the full UTM stage. Mine just uses formulas, which you can copy down.

http://maps.ozultimate.com/wiki/downloads

Ken - your map bounds are not quite right. You need to look at all 4 corners to get the max/min easting/northings, not just the top left/bottom right. For example, for Wollangambe, you have the min easting/max easting/min northing/max northing as
244160/267758/6290483/6303760
But the northing bounds are actually wider
244160/267758/6289895/6304346
This is because the UTM grid doesn't line up with Lat/Long, and the angle that it's offset by varies with the distance to the centre of the zone.