Converting AMG66/AMG84 coordinates to MGA using Trimble Terramodel

Step 1. Import Latitude, Longitude & Height points data into Terramodel. If the data is already in Terramodel, skip straight to Step 5.

From the main menu, select File / Download Import / ASCII pts


Step 2.Select a PTS or data file


Step 3. Change the data order to n,e,z if the file has Latitude, Longitude, Height as below.
   Note: Latitude, Longitude  must be in decimal degrees (DDD.dddddd)

Step 4. Set the displayed precision of the coordinates to check values.
Menu / Settings / Unit Settings / Precision as seen.

You can then use Coordcon to convert the points to Eastings and Northings.

Step 5. From the main menu select Cogo / Utilities / Coordinate conversion or type coordcon in the Terramodel command line then press enter.

Step 6. Click the [Coordinate systems] button


Step 7.  Change the From system to LL-360 as above. This is a generic format for Latitudes and Longitudes in decimal degrees. Longitudes are east values only in the range 0 to 360 degrees.

In this example we will assume the Lats/Longs are on the AGD66 defined spheroid and the required Coordinate System is AMG66 ZONE 55.


Step 8. Change the To system to AMG66 Zone 66 as above, then click the [Ok] button.

Note: If the Coordinate System has not been defined, see Creating a new Coordinate System in Terramodel.

Step 9. Click the [Multiple points] button then use the selection tools to select the points to be converted.


Step 10. A list of the conversions (as below) may be produced by clicking the [List] button.

Step 7. You should now have the above dialog on display which shows you are ready to convert from AMG84 Zone 55 to MGA Zone 55.

Click the [OK] button.

Coordinate Conversion Report

Input CS: Generic Lat/Long’s, Degrees, 0 ==> +360
Output CS: AMG66 ZONE 55 WRT GDA94
Input Units Assumed: DEGREE
Output Units Assumed: METER

Point     Latitude       Longitude                              North                    East
1 -32   03’10.2339″   145 44’22.0964″ ==>> 6453000.0000   381000.0000
2 -32   03’15.2227″   145 44’10.0138″ ==>> 6452842.6730     380684.9260
3 -32   03’15.2227″   145 44’10.0138″ ==>> 6452842.6730     380684.9260
4 -32   03’15.2358″   145 44’10.0308″ ==>> 6452842.2730    380685.3780
5 -32   03’15.2460″   145 44’10.0438″ ==>> 6452841.9650     380685.7220
6 -32   03’15.2889″   145 44’10.0992″ ==>> 6452840.6610     380687.1890

Step 11. Click the [Convert] button to convert the coordinates in Terramodel. 

Step 12. Confirm a value (eg Point 1) using GeoCalc as shown.