Open Source GPS HOW TOUploading GPS-Recorded Routes to the Marengo Route PlannerBy Martyn C Davis(Note this version is specific to the Mac - for Windows, see here)I've been asked on several occasions how to get a recorded route OFF your GPS unit and onto the Marengo Route Planner. This is the opposite way to the methods I describe in the original HOW TO, which details how to create a route and upload it to your GPS unit. Doing it the other way is useful for several reasons: you might have ridden a nice, unplanned route, and you want to save it and program it in to your GPS. Or you might have wandered off course on a programmed ride, and you want to compare your actual route to your original planned route. OK, firstly we need to get the data out of the GPS unit. As usual, GPSBabel is our tool of choice. PLEASE NOTE that I am not affiliated with this fine piece of software. If you have questions regarding it, check their forums. Any questions regarding GPSBabel which are misdirected my way will be ignored! Right, we need to be aware of definitions. In GPSBabel, Waypoints are individual position markers. Routes are the things we create when we UPload a route to the device, and Tracks are what we are interested in here: they are what the unit stores when you are recording a route as you ride. So, in GPSBabel, we need to specify that we want to download tracks: 
Now, before you press "Save File...", we need to set a filter. This is because your GPS Unit stores a trackpoint every few feet when it's recording. Which means even a short ride will have potentially thousands of points recorded. If we tried to load all of that into the Route Planner, it would (a) take forever and (b) use a LOT of resources. Plus also it would simply be overkill - you only really need points at junctions to define a route successfully. So press the "Select..." button next to the "Filters" section, which brings up the following dialogue: 
Notice that I've checked the "Merge waypoints separated by less than..." checkbox, and, arbitrarily, chosen 500m as the distance for minimum separation. It's worth noting that this filter is not very clever - if you have an "out and back" route which goes along the same road in both directions, you'll lose the later points. The filter ideally should filter out points which are close in both time and distance. But currently it doesn't. Now press "OK" and, when back at the original dialogue, press "Save File...". Assuming you've got your GPS attached and there's a route on it, you should be able to save your route to a file. Now this saved file is in a somewhat different format to what is required by the Marengo Route Planner. However it's now easy to convert your file via my quick-and-dirty converter which you can find right here. Upload the file which you got out of GPSBabel, and then copy the resultant text, which you should then be able to paste into the Route Planner. Please note the following regarding the converter: If you do not apply the filter when you extract your track, you will end up with a huge file. This will be rejected by the converter and you won't get ANYTHING out of the other end. Please ensure that you ONLY have ONE track on your GPS when you do this: if you have multiple, it will probably confuse things (I haven't tested this scenario). I do not keep your uploaded tracks, in case you are worried about privacy (don't worry, I won't be joining you on your next ride :). Finally, it's a FREE tool, people! If you can't get it working, I'll be happy to help, providing you donate (see the PayPal link at the bottom of this page). For more information, please see the discussion forum at http://www.marengo-ltd.com/mapforum/ I'll be interested to see how it works with all different GPS units too - drop me a note to tell me what you've got it working with. Finally, you may also contact me here. Queries will be given much more attention if you accompany them with a small donation (see the PayPal link at the end of this page).
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