GPS for Dummies.pdf - Engineering Surveyor

Chapter 13: On the Ground with Maptech Terrain Navigator225Unlike DeLorme’s Topo USA, Back Roads Explorer uses raster maps (scannedversions of paper maps), which contain more detail. If you prefer more of atraditional looking map to one that looks like it was computer-generated,you’ll like Back Roads Explorer.Raster maps take up more disk space than vector maps because they’rescanned images of paper maps. Vector maps are smaller because they’re composedof lines and shapes. For example, the raster map data for the entireUnited States that comes with Back Roads Explorer fits on 17 CDs, but thesame vector data in Topo USA comes on 6 CDs.With the option of overlaying up-to-date roads over topographic maps, BackRoads Explorer is ideal for basic navigation and is especially well suited for4 x 4 enthusiasts who use a laptop and GPS receiver.TOPO!National Geographic’s TOPO! line of software provides 1:24,000 maps foreach of the states and is comparable with Maptech’s Terrain Navigator andDeLorme’s 3-D TopoQuads products. (A screenshot of a TOPO! 1:24,000 scalemap is shown in Figure 13-10.)Figure 13-10:TOPO!1:24,000scale topographicmap.