How are Garmin and Magellan topo maps different?
Over at Groundspeak, Geocaching.com‘s message forum, Peter gave a great explanation of the differences between Garmin and Magellan topo maps: “As Sputnik indicated, the approaches taken by Magellan and Garmin are different. Garmin uses Digital Raster Graphics (DRG) to basically create an image of the USGS 1:100,000 series maps. Therefore their maps have all the detail and accuracy provided by those maps, and nothing else – which means they lack most road names and anything built since the maps were last updated (20 years or so ago in many areas). But they do show the features included by the USGS: springs, fire roads, quite a few trails, etc. Also note that the 1:100,000 maps are metric so the contour spacings are based on rounded numbers of meters. When your GPS is set to feet the spacings look a bit strange (e.g. contours at 164′, 328′, 492′, etc.) Magellan’s topo maps are instead based on the Digital Elevation Model (DEM) technology where elevations are sampled in a grid pattern and
