As a recent owner of a Garmin GPS Navigation System I’ve been amazed at the accuracy of the data and the maps. However, until the recent past, the machine had only travelled around my local city and a couple of short trips down the highway; nothing too elaborate. Last week my parents took the unit with them to Kelowna, British Columbia.
Upon their return I decided I should spend some time trying to extract data in a useful format, something I could use to recreate the trip in Google Maps / Earth, Microsoft Virtual Earth or something else.
So the rest of this post might be common knowledge for those who have been using their GPS for some time but this is all new to me, so I’m going to try and summarize. In later posts I will try to get into a few more specifics of certain applications.
GPX
The GPS Exchange format file was introduced in 2002. Most GPS units made since then are able to store files in that format or are able to convert to and from this format from their native file structures. GPX files are XML based, here is the Wikipedia article and a link to the official GPX Website.
The GPX format contains three data types:
- Waypoints – are a collection of locations, typically not ordered in any fashion, such as a group of landmarks, or locations you have visited or have an interest in.
- Tracks – are also a collection of locations but are a record of where you have been, thus they are ordered by location and time.
- Routes – are suggestions of where you might go, so are only ordered by location
GPX Files on Garmin Nuvi
To get GPX files off the Garmin Nuvi models, simply attach the GPS unit to a computer via USB. Assuming you have loaded the Garmin Communicator software (Nuvi Drivers) in the past the Garmin unit will appear as a removal drive to the operating system. In a folder called GPX is the current.gpx file. There are a few more files in my unit but they are fairly small. I’m not sure yet if the file rolls over, but I am wondering if I should rename it on a regular basis or not. If you copy this current.gpx file off you will be able to edit and manipulate it. There are many websites that publish routes in GPX file format. If you copy the downloaded GPX files onto the device, the next time it boots up those routes and associated waypoints will be there.
Google Earth
I will include more information on various items you can accomplish with GPX files and Google Earth later, mostly because I’m still playing with it, and do need some material for later posts. For now, launch Google Earth and drag the GPX file onto the screen, it will offer some options and then import the file. You should see individual waypoints and a representation of the track you took. (Note: Since Google Earth version 5, GPS support comes with the free version rather than just the Professional version, connect the Garmin via USB, go to the GPS menu in Google Earth and select Import).
GPSVisualizer
While searching for ways to manipulate GPX files I ran across this free web service, GPSVisualizer. You can upload GPX files to this site, fill in several options in terms of output format, and receive a file. This process normalizes the data a little bit, making the end result much smaller, it will also color code the route in terms of time or elevation. I uploaded my Kelowna trip GPX file and got back a KML file (Google Earth’s native file format).
EasyGPS
EasyGPS is an easy (and free) way to transfer waypoints, routes, and tracks between your computer and your Garmin, Magellan, or Lowrance GPS. Once this software is downloaded and installed it can read, edit, organize and create GPX files. Those files can then be uploaded back in to the GPS unit if you wish.
