Before you can use your map in ExpertGPS, it must be added to the Map Library and calibrated.
To add a new map to the Scanned Map Library, clickon the , under .
The Open Scanned Map dialog will appear. Select a JPEG, TIFF, PNG, or Bitmap image of your map.
In the Edit Scanned Map dialog, enter a descriptive name for your map, and specify the projection information located on the collar of your map. If your scanned map came with a calibration file (worldfile or map calibration file), it will automatically be detected and used. Otherwise, you will need to manually calibrate the map so that your GPS data appears correctly on it.
In order for your scanned map to display correctly, ExpertGPS needs to know the details of the projection used when the map was printed. This information should be printed in the margin or a corner of your map.
If your map doesn't have projection information listed, and it covers a small area (like a county, town, or regional park), you can safely choose the Mercator projection and get reasonable results. It's only when you start working with maps that cover a whole country or continent that the distortion due to the Earth's curvature starts to make the exact projection details necessary.
Enter the latitude of the two standard parallels, in degrees and decimal minutes.
The standard parallels for maps showing all 50 US states are typically 20º and 60º North.
The standard parallels for maps showing the 48 conterminous US states are typically 29º 30' and 45º 30' North.
Enter the longitude of the central meridian. This is the only line of longitude on the map that is vertical. All other meridians are at an angle.
If the Central Meridian is not explicitly listed in the map margin, determine the line of longitude that is vertical on the map. In the example below, the 0º and 20º East lines of longitude slope away from the vertical at the same angle. Therefore, the vertical Central Meridian lies halfway between them, at 10º East.
Enter the latitude of the natural origin of the map.
Enter the false easting used by this projection.
Enter the false northing used by this projection.
Enter the scale factor at the natural origin of the map.