GPS Data

Tracks: Most GPS receivers will record a track (a series of data points taken every few seconds or when you move a small distance).  This file of points is often quite large and may hold thousands of location.  These locations form a track that shows where the GPS receiver has been over the period it was recording the track.  This track file can be plotted on Google Earth.

Track files generally contain not only locations, but may contain the time at which each point was recorded.  This type of file can be used to (almost) automatically link (i.e., georeference) photos to locations.

Waypoints: GPS receivers generally let you mark a point by pressing a button.  Generally, you also enter some label to mark this point.  You get as many waypoints as you mark.

Waypoint data is often useful if you want to add information to specific locations.  For example, you can reference data you have collected with the locations at which they are collected.

Extracting GPS Data from a GPS Receiver

Most GPS receivers provide software to download both track and waypoint data.

A handy utility, GPS Trackmaker, can be used if you don't have other software.  This program is primarily designed for use with Garmin and Magellan receivers.

Converting GPS Data

The format of GPS data varies between GPS receiver manufacturers.

The free web resource, GPS Visualizer, converts most of the manufacturer-specific formats to a more general format.

For example, you can convert a file of waypoints to a format (text, comma delimited) that can be used in Excel.  That lets you add data to waypoints, and the enhanced waypoints can then be plotted using Google Earth (after another conversion using GPS Visualizer).

Other reasons you might want to convert your GPS data, such as a track file, is to edit out duplicate or spurious points.