Eye4Software Hydromagic

Hydrographic Survey Software


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Manage map datums

To open the "Manage Datums" window, select "Options" => "Coordinate Systems" => "Manage Map 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 that are already in the database, click here.

Manage map datums


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:


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.

Folder for datum shift grid files


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.


Deleting a datum

You can delete an datum definition, by selecting an item from the list and clicking the button "Delete".
The software will show a popup to confirm that you are sure you want to delete.

Please note that you cannot delete datums that are used in a grid 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.