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January 6, 2007

GPS download survival guide

Filed under: GPS,Howtos / tips / tricks — mtbguru @ 12:37 pm

GPX, used by MTBGuru, is a great and open standard format for GPS data – not all GPS manufacturers make it easy to download your data in this format though, so we thought a brief GPS download survival guide was on its place. If the software that came with your unit doesn’t support saving in GPX, this post is for you – and even if it does you may discover some interesting new tools here.

If you don’t feel like reading the whole post, one word: GPSBabel – Robert Lipe’s tool runs on about every OS, is free and totally awesome, use it and donate to support the project.

GPSBabel can be used to read, write and convert GPS data in an entire range of formats that are in existence. It can directly interface Garmin and Magellan units using the USB or serial port on your computer. It also understands TomTom and Suunto file formats. And so on and on, check here for a list of supported formats.

It’s a console mode tool but has nice graphical front-ends in both Windows and Mac OS X. Below is a screenshot of the front-end for OS X called GPSBabel+, written by Karl Smith (and can be downloaded here). I use it to download data from my Garmin Edge straight into GPX files on my Mac iBook.


GPSBabel+
GPSBabel+ (for OS X)

Hook up the GPS to the USB port, set up the input and output options as shown in the screenshot, and press ‘Save File’, and you get all data on your unit in a GPX file.
The GUI front-end on Windows works similarly.

Another very cool software tool on Mac OS X is LoadMyTracks (screenshot below), which is available as a free beta version. It simply does what its name says, and you can save into GPX or Google Earth’s KML format. Besides Garmin and Magellan, also TomTom devices can be hooked up directly.



LoadMyTracks (for OS X)

On Windows, a very nice and free program is Sporttracks – you can use it to download data directly from GPS and save into GPX.

A good web application to convert GPS data is GPSVisualizer. It uses GPSBabel as its conversion engine.

Undoubtedly, there are many other software tools and programs out there that can do the job – I focused here on a few free or inexpensive tools that I think work very well. If you know of other and/or better tools, feel free to mention it in the comments.

Let me wrap up by saying that I’m a bit bummed about what Garmin is doing in this area: MapSource on one hand (that comes a.o. with the Etrex series of GPS units) allows you to export your data into GPX without any trouble but in Training Center (that comes with the Edge and Forerunner series) it’s a real headache to get your data out. Granted, .hst and .crs are open xml formats, containing additional information such as heart rate etc, and with some effort it’s not too hard to convert these, but why make us go through the trouble?

January 4, 2007

Multiple tracks in GPX files

Filed under: GPS,Howtos / tips / tricks — mtbguru @ 1:59 am

When a GPX file is uploaded to MTBGuru, the file is examined and probed for GPS tracks. GPX files may contain single or multiple tracks.

When you look at the file in a text (or xml) editor you can identify the tracks as content delimited by <trk> and </trk> tags. And tracks themselves may consist of a number of ‘track segments’; segments are identified by the <trkseg> and </trkseg> tags.

So how does MTBGuru interpret these files? Our goal was to make it as easy as possible to fetch the data for your trip, and hence we needed to be quite flexible, as different GPS units will store their data differently. Even using a single device there are many different ways or tools to download the data, each potentially resulting in differently structured GPX files.

In the simplest case, the GPX file contains only a single track – nothing special is going on then, the trip is created using the data in this single track. Track segments are concatenated and displayed as a single trace on the map.

But what happens when multiple tracks are present? When data is downloaded from the GPS, often times it will come as a single file containing all the tracklogs stored in the memory of the device, converted into a single GPX file. This GPX file will typically contain a number of different tracks representing the various tracklogs you’ve recorded over time.

ScreenshotUploadGPS.jpg

As you may have found out, there are two ways to create a trip from GPS data in MTBGuru (see figure):

  • By Upload GPS Data: after you upload a GPX file, you are presented a screen displaying all tracks in the file (see screenshot 1 below), as well as information such as the number of points and date and time. You can then select an individual track and base a trip on it by clicking Create trip.
  • By Add a Trip: here you start by creating the trip first, and then attach a GPX file to it using Upload GPX file. If your GPX file has multiple tracks, you’ll be shown a different screen now, that allows you to select and combine multiple tracks (using checkboxes) for this one trip (see screenshot 2 below).

The second option is very useful in cases where the GPS unit was for instance suffering intermittent reception during a trip. What typically happens then is that the tracklog in the memory of the device is broken up into different tracks, with ‘gaps’ in between them. You can now easily stitch everything back together by selecting the relevant tracks using the checkboxes – the time and distance gaps between the different tracks are indicated and help you decide whether the tracks belong together. The combined set of tracks is displayed as a single trace on the map – the gaps may or may not show up as visible artifacts, depending on the amount of reception loss.

The first option is preferable if your GPX file contains data from various trips or rides, from which you’d like to select and create individual trips.

P.S. GPX files may also contain other data types such as waypoints and we do anticipate support for the latter – currently all waypoints in GPX uploads are stored in our database, such that they can be accessed and used in the future.

Screenshot 1, after uploading a multitrack GPX using Upload GPS Data
Gpstracks-Screenshot1


Screenshot 2, after uploading another multitrack GPX file using Add a Trip
GPS tracks screenshot2


January 1, 2007

A happy 2007!

Filed under: Admin — mtbguru @ 4:58 am

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MTBGuru wishes everyone a happy and safe new year – and may you all take on lots of exciting outdoor adventures, discover new trails and routes, and share your experiences.

We’ll soon get out of our holiday hibernation and get back to work to improve the site and implement new features (more about that soon).
And to ride, of course – for new year’s resolutions I was thinking of signing up for a 100 mile race (Park City, Leadville?) or doing a 24 hour event (team? or perhaps even solo?), though I may be getting carried away a bit.

cheers,
Dirk & Tom

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