GOM - the Global Overlay Mapping System

How to use the Overlay Mapping System

This user-guide is designed to be read whilst looking at the Global Mapper Screen. Open both windows on your monitor, or print out this topic before opening the Global Mapper.

Start the Global Mapper by clicking on its icon. The screen that opens in front of you contains 3 areas: To the left, the navigation area where you can easily select the map required, to the top a line of buttons that turn on or off the map overlays, and the main area of the screen, for the map itself.

The first thing to do is to chose one of the 34 maps. These are of two types, the 7 continental maps, and the 27 sub-continental maps. To select & load a continental map, simply position your cursor and click on the required area of the small world map, or position and click on one of the 7 buttons under the map, marked EU, AS, AF, NA, OC, & AN. To select a sub-continental map, move your cursor over one of the 7 buttons described above. The area beneath the buttons will change to show a map of that continent. Slide your cursor down on to this map, and then move it around to locate the active areas, which will change color once you are over them. You can then click to select & load that sub-continental map.

When the map loads, you are initially presented with only the background layer. This contains the basic land and country outlines, plus the names of relevant water features, seas, and oceans. You can now add any of the other 12 layers, by clicking on the 12 larger buttons above the map. They are, left-right:

• Filled country outlines, with region borders.
• CQ Zones, defined by color or border.
• ITU Zones, defined by color or border.
• Time Zones, defined by color or border.
• Colored relief or topographical map
• Grid Locator mesh, with added grid locator information.
• Lattitude and Longitude mesh, with regular number idents.
• Country, regional, and island names.
• Capital and other major cities.
• Amateur Radio prefixes, and prefix borders.
• IOTA code numbers, corresponding to the RSGB system.
• Flags of the World, modified in aspect-ratio to give a constant size.

You can turn on one or more overlays simultaneously, to compare how the data relates. The layer that is currently on top is indicated by the horizontal colored line below the buttons. To bring a buried layer to the top, simply turn it off then on again. When a new map is selected, any existing layers will be turned off automatically.

If you are viewing the map on a smaller monitor, or just want more of the map to be displayed, you might find it useful to turn off the navigation tool bar, on the left of the screen. To do this, click on the 'Tools' button, located to the right of the upper tool bar. The map will re-open without the navigation tool bar, leaving just the overlay controls as before. To select another map, you will have to turn the navigation tool bar back on, by clicking on the 'Tools' button once more.

Whilst a map is displayed, a variety of very accurate positional, distance, and bearing information is displayed on the status bar, at the bottom of your browser screen. For more information about this, visit the Status Bar help-page, by clicking HERE.

An extra feature with every map, is the dragable Scale-Bar, which can be turned on and off by clicking on the 'Scale' button, located to the right of the upper tool bar. For more information about this, visit the Scale-Bar help-page, by clicking HERE. Note that the Scale-Bar is only dragable when it is the current top layer. In other words, if you turn it on, then turn on another overlay, you will not be able to drag the Scale-Bar about, as the new overlay takes precendence in the stacking order. To regain control of the Scale-Bar, simply turn it off then on again.

To check the latest version of Software and Overlays that you have, click on the 'About' button, located to the right of the upper tool bar. For more information about this, visit the About-Button help-page, by clicking HERE.