Great Circle Setup
The 'Setup' Tab-Page sets the Map Center-Position, the Map Projection, chooses the current Map Background Image, and sets the Form Background Color.
The Map Center-Position can be set to either the Home Location, which is defined in Program Options, or a Custom Location, which you can enter into the Latitude and Longitude boxes in the 'Map Center' panel. The values entered should be in decimal degrees, in the format: 'dd.dd' or 'ddd.dd'. Use negative values for South and West. After entering values by hand, click the 'Custom Location' radio-button. If that button is already selected, click the 'Refresh the Map' button.
You can also re-center the map by clicking at any location.
You can set the map projection using the radio-buttons in the 'Projection' panel. There are four different projections to choose from:
Azimuthal Equidistant: also known as a 'Great Circle Map'.
Lambert Azimuthal Equal Area - North: ideal for visualizing the Arctic.
Lambert Azimuthal Equal Area - South: ideal for visualizing the Antarctic.
Orthographic: also known as the 'World from Space' map.
Not all map features are available for each projection-type.
You can set the image used for the map background with the control in the 'Map Background Select' panel. The Great Circle Mapper can use any of the 23 available background images.
Background number '17' is a little bit different from the others. It shows a NASA Blue Marble 'Next Generation' image with Topography and Bathymetry, but here's the fun bit: the ice and snow cover varies depending on the month that is selected in the Date/Time Picker in the 'Solar' Tab-Page. Try selecting Background Map 17, then go to the 'Solar' Tab-Page and select a Custom date/time, then alter the month by clicking it then using the up/down arrows, and then click 'Refresh the Map'.
The final panel sets the Form Background Color: this is the plain color that surrounds the current map, and the Compass Rose color. You can different colors for each of the 23 maps.