Find “Missing” Elevations with GPS Visualizer
The problem: Sometimes you have geographic data that consists only of latitudes and longitudes, but you want to know the altitudes as well — because, for example, you want to colorize points by height above sea level, or draw a profile of a track. Here are some common reasons why you might have “flat” or incomplete data:
Your GPS device does not log altitude, or you had poor satellite reception when you recorded the track.
Your GPS device does log altitude, but it’s not very accurate.
You drew a track using the drawing tools in Google Earth or a similar application, like GPS Visualizer’s Sandbox.
You have a KML file that came from Google Maps or Google Earth’s “driving directions” feature.
You created a route in Google Maps and have the URL of that route.
You have an NMEA log file that contains only “GPRMC” sentences, not “GPGGA.”