Polyconic Projection Parameters Dialog
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.
- Central Meridian
- 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.
ExpertGPS works with hundreds of GPS receivers, including all Garmin Drive, nüvi, eTrex, Colorado, Dakota, echoMAP, GPSMAP, Edge, Forerunner, Montana, Oregon, and Rino models, Magellan eXplorist, Meridian, and SporTrak GPS receivers, and Lowrance iFinder, HDS, Elite, HOOK, LCX, and LMS GPS chartplotters and fishfinders.
Find your GPS on the ExpertGPS compatibility list.