Coordinates and measured parameters can be expressed in various units. Worldwide, many differnt units have bee established, and allthough international conventions are existing, people use the units they are familiar with. The same holds true for coordinate systems, map datums and map grids.
Therfore, it is necessary to be able to switch or transform coordinates and parameters into various units. You can access this window where all units are summarized through the Units icon from the Standard symbol bar.
A window will open with 3 tabs: Coordiantes, Units and Grid:
Under the Coordinates tab, you select all parameters which refer to coordinates systems:
Below you can choose whether you want to use the Internation format notification or wether you want to use S (South) and W (West) as default prefixes. - Otherwise N (North) and E (East) are the defaults.
In the field Map Datum you must specify to which Map Datum the coordinates refer to. The default setting is WGS 84 which evolves more and more to a kind of international standard.
Please note that coordinates without specifying the Map Datum are missleading and not exactly defined! Using the wrong Map Datum may result in an offset of several miles! Dangerous situations can be the consequence and you might get lost or at least will not find the position you wanted! So always make sure to care for the map datum when enetering or forwarding coordinates!
On the righthand side of the coordinates tab window you find several Linear Coordinate Systems like UTM, MGRS or the French Grid IGN and also all National Coordinates Systems in a pull-down menu. If you need to work with such National Coordinate Reference Systems, tickmark the option National Metric Grids and choose from the list below. If you should not find the appropriate one in the list, you can add a new definition. For further details see chapter QV System - Map Datums, Grids and DEMs.
Remark: As National Coordinate Reference Systems usually imply a specific Map Datum, the Map Datum field is disabled in order to avoid using such a National Metric Grid with an inadequate Map Datum.
The Units tab refers to all dimensions of measured values:
Here you can define the units of you choice for:
Under this tab you also have to specify if course readings and bearings should be refered to Geographic or Magnetic North.
Finally, the Grid tab refers to the parameters of a Grid which you might wish to use as an overlay on your map:
This might be especially helpfull when printing maps. The options are:
On the lefthand side you can also select the color of the gridlines and wether you want them in bold style.
At the buttom of the window you will find an option to apply the settings to all QV windows. This is the default setting.
Important Remark: Please note that the grid will be created in the coordinate system which you have defined in the Coordinates tab!