GPS for Dummies.pdf - Engineering Surveyor

Chapter 4: Grasping Important GPS Concepts77Most GPS receivers support mapping. At the very least, a GPS receiver hasa simple plot display, a map page that shows waypoints, tracks (see theupcoming section, “Making Tracks”), and your current position. Moreadvanced (and expensive) GPS receivers support more sophisticated maps;your waypoints and tracks appear along with roads, rivers, bodies of water,and whatever built-in features the map has. When the map page is displayed,you can zoom in, zoom out, and move around the map with an onscreencursor that you control with buttons on the GPS receiver.A map page can be orientated two ways: so either the top of the screenalways faces north or the top of the screen faces the direction you’re traveling.Orientating the screen to the north is probably the easiest if you’re usedto working with maps, which usually are orientated with their tops to thenorth.Following RoutesA route is a course that you’re currently traveling or plan to take. In GPSterms, a route is the course between one or more waypoints (see Figure 4-4).If multiple waypoints are in a route, the course between two waypoints is aleg. A single route can be made up of a number of legs.LOOPLAKEFigure 4-4:Routes arelines thatdefinecourses oftravelbetweenselectedwaypoints.WTRFALLPRKLOTTRAILXSuppose it was a beautiful day, and you went hiking, deciding to make a loop:hike from a parking lot trailhead to a scenic waterfall, go over to a lake forsome lunch on a sandy beach, and finally head cross-country until you reacha trail intersection that would take you back to your starting point at theparking lot. You’ve hiked in the area before; in fact, you’ve visited each ofyour planned destinations and marked them as waypoints in your GPS