Manage Datums - Eye4Software Coordinate Calculator

We recommend managing your geodesy configuration database from the "Eye4Software Coordinate Calculator", which is a freeware tool that is shipped with Hydromagic. To start the "Coordinate Calculator", select "Geodesy Calculations" => "Coordinate Conversion..." option from the "Tools" menu as shown below:

Select the "Coordinate Conversion..." option to start the Coordinate Calculator.

The database containing all geodesy definitions, like ellipsoids, datums, coordinate systems and correction grids is stored in the "C:\ProgramData\Hydromagic\Database\" folder, and it is shared by multiple applications, like Hydromagic Survey, Hydromagic Dredging and the Coordinate Calculator. Most of the content has been taken from the EPSG geodetic database and it will be updated regularly.

All geodesy definitions are stored in a shared database file.

Supported datum transformation methods

In Hydromagic, you need to set the transformation parameters to convert to WGS84 for each newly created datum. The following transformation methods are supported:

• None (no transformation needed);
• Molodensky (3 parameters);
• Bursa Wolf (7 parameters);
• NADCON;
• HARN/HPGN;
• NTv2.

Grid files

The last three methods mentioned above do not require parameters, but you have to specify a valid grid file. For NADCON and HARN/HPGN, files for North America are shipped with the product.

To add your own NADCON, HARN or NTv2 files, just copy the file to the "NADCON" or "NTv2" folder in the "Program Data/Hydromagic" installation directory.

NADCON and HARN files are pre-installed in the "NADCON" Program Data folder.

Managing map datums

To open the "Manage Datums" window, select "Tools" => "Preferences" => "Manage Datums..." from the menu. Using this window, you will be able to view, delete or modify existing datum definitions, or to add your own. For a list of datums already in the database, click here.

The "Datums" dialog can be opened from the "Tools" menu.

Datum list

When clicking an item in the list, its parameters are displayed below the list. You can edit these parameters by clicking the "Modify" button.

The 'Datums' dialog can be opened from the 'Tools' menu.

Deleting a datum

You can delete a datum definition, by selecting an item from the list and clicking the button "Delete". The software will show a popup window to confirm the deletion. Please note that you cannot delete datums that are used in a grid definition.

You have to confirm deletion of a datum definition.

Modifying a datum

You can modify a datum by clicking the "Modify" button after you selected a datum from the list. After clicking the button, the "OK" button text will change to "Save". Clicking the "Save" button will save the modifications, clicking "Cancel" will keep the old data.

Adding a datum

To add a new datum definition, click the "Add" button. When adding a new definition, it is required to specify a name for this datum, as well as the ellipsoid used. Other fields are optional and are defaulting to 0.0 when not used.

Please note that the X,Y and Z translations have to be entered in Meters, the X,Y and Z rotations are entered in arc seconds. If you have a datum definition that uses radians, you have to convert from radians to arcseconds first: 1 radian = 206 264.806 arcseconds.

Click the "Save" button to store the newly created datum, by clicking 'Cancel', the input is ignored and you will return to the list.