Australian Datum DGA94 and MGA94 Projections

If you need to use the Map Grid of Australia based on the GDA 94 datum, you can define these as user-defined coordinate system and datum, respectively within your PC-GIS 9, PC-GPS 9, PC-MAPPER 9, PC-MAPPER AI 4, CMT-Forester 10, CMT-SURVEY 9 or COGOCAD 9 software program.

The Edit Datum and Edit Coordinate System buttons are available when you select “User Defined” under Map – Coordinate System.

The screen shots below show the parameters to enter for defining the GDA 94 datum and the MGA 94 Zone 55 projection.


How to transfer user-defined coordinate system to PC-GPS running on new computer

Your user-defined coordinate system, plane and datums are stored in the following files, respectively.




Please copy these three .sys files to the PCGPS program folder on your new PC. Then you will see your user-defined coordinate system available in PC-GPS on your new PC.

If you are unable to access the files on the XP hard drive, then you could re-create the coordinate system on the PC-GPS running on your new PC.

User-defined coordinate system for Florida

” I am having problem importing this shapefile into my PC-GPS map. It always is way south of where it should be. Do you have any suggestions?”

This set of Shapefiles was created using the Florida projection, not the UTM coordinate system. The coordinate system used by the Shapefiles must agree with the coordinate system used in PC-GPS; otherwise the Shapefiles data will be interpreted incorrectly.

You can create a User-defined Coordinate System in PC-GPS for the Floridat projection as follows:

1. Click on ‘User defined’ under the Map/Coordinate System option and select Meters as the distance unit.

Then click “Edit Coordinate System”. Type in a coordinate system name like “FLORIDA” and click <ADD>.

2. Select “NAD83” as the Datum and “Albers Equal Area conic” for the Projection. leave the zone number as it is.

3. Enter the following parameters into the appropriate spaces:

Central Meridian: 84 00′ 00” W
False Northing: 0 meters
False Easting: 400000.0 meters
Latitude of false origin: 24 N
North Parallel: 24 N
South Parallel: 31 30′ N

Click on OK to save the projection. Click on OK again to select this user-defined coordinate system as the active coordinate system. Then import the Shapefiles.

If you want the Shapefiles to go into an existing job, then first open that job file, change the coordinate system to the Florida projection, then import the Shapefiles.

If you would like to use the Florida projection in iCMTGIS II, then copy the user_cor.sys file to the Documents folder for iCMTGIS II via iTunes. (The file name needs to be in lower-case for iCMTGIS II to use it.)

Why can’t I update a user-defined Albers coordinate system?

A user reported: “I am unable to update an Albers coordinate system. I am unable to create a new user-defined coordinate system.”

Later, the source of the problem was identified: “Because of the security settings only those users with Administrative privileges are able to edit the parameters.”

To create or update a user-defined coordinate system, the software application will need to write to the file in which these parameters are stored. This is also true for a few other functions, such as registering the parameters for geo-referencing an aerial photo. Ideally, you will log in as the Administrator. Otherwise, please make sure your have the necessary security privilege to the folder in which the data files are stored.

Where is my user-defined coordinate system?

PC-GIS, PC-GPS and PC-MAPPER will let you create a user-defined datum and/or a user-defined coordinate system. The user-defined datums are stored in the file named USER_DAT.SYS. The user-defined coordinate systems are stored in the file named USER_COR.SYS.

If you have defined a local NEZ coordinate system, it will be stored in the file named USER_PLA.SYS. These .SYS files must be present in the software program folder for the user-defined spatial reference systems to be available in the Coordinate System setup screen. Therefore, when you copy your job data files for use on another PC, you should also copy these .SYS files over.

Similarly, if you wish to make use of the user-defined datums and coordinate systems on your mobile device, please copy the above .SYS files to the data folder of your mobile device.