I want a Windows program to analyse GPS tracks in detail
January 15, 2012 2:37 PM   Subscribe

Is there free or cheap software for analysing GPS tracks in detail? I want to be able to take a track produced by something like My Tracks (from an android phone) and look at it on my desktop computer, where I would like to zoom in on particular sections of the route: how fast was I going here? How steep is that hill?

If I look at the elevation profile in Google maps, it's usually much too compressed to be helpful: a nineteen mile ride is fitted into three sawtooth inches of screen. But I would like to be able to see the elevation profile and speed data corresponding to a particular hill on the map. Is there anything out there that would do that without fuss and without costing too much money?
posted by alloneword to Computers & Internet (11 answers total) 12 users marked this as a favorite
Try using G7toWin to get the data off your GPS and GPS Visualizer to map it.
posted by Confess, Fletch at 2:46 PM on January 15, 2012

FWIW, I wouldn't rely on the elevation data from GPS either - it's base accuracy is usually specified to be 1.5 x horizontal accuracy (e.g. 1.5 x ±15m = ±22.5m), or worse depending on the visible constellation (and the optimum constellation for determining altitude is pretty much the worst constellation for horizontal accuracy).

On top of that, altitude is measured from the centre of the available satellite's modelled orbits (i.e. somewhere near the centre of the earth), minus the surface altitude of the earth at your location as modelled by the specified geodetic model used (e.g. WGS-84).

Absent of any outside corrective methods (e.g. D-GPS), elevation of any one recorded point can easily be out by ±40~50 metres or more.
posted by Pinback at 3:17 PM on January 15, 2012 [2 favorites]

BUT, it's not like the elevation data will suddenly jump from one end of it's accuracy scale to the other, so the offset from one point to the next will be OK-ish. For hobby use it's fine to get a profile, as long as you remember that the absolute numbers might not be 100% accurate.

As suggested GPS Visualizer has a lot of awesome features, especially for free!
posted by trialex at 3:22 PM on January 15, 2012

Seconding GPS Visualizer, if you want something quick to work with existing tracks. It has a lot of different options for drawing graphs from data and can get you the profiles you want. You can bookmark specific form settings for repeated use, too.

If you're specifically interested in walking consider using RunKeeper. It's nicely optimized for walking and running. You need to use their tracking app though, I don't think it can import from other apps. k

Pinback may be right in theory about GPS altitude, but in practice it works pretty well. Both plain GPS itself and the hybrid location mechanisms in phones. If you're really worried about it, GPS Visualizer has a way to infer altitudes from a digital elevation model based on your 2d ground track. That's not a bad way to find elevation gain on trails.
posted by Nelson at 3:23 PM on January 15, 2012

Trimble outdoors lets you upload tracks to their website then look at them for free, with somewhat better elevation profiles. Not sure it's all of what you're looking for but might be worth checking out. Also integrates with Backpacker's GPS Trails App (full disclosure, I work for Backpacker).
posted by rzperllian at 3:27 PM on January 15, 2012

Strava can do what you want. You can zoom in on any part of a segment and see speed, elevation, heart rate and power in as much detail as is reasonable to desire.

Also, some Android phones and most bike-specific GPS units (like the Garmin Edge 500) have a barometric altimeter so the issues with GPS elevation inaccuracy are moot (though barometric measurement has its own problems).
posted by klanawa at 3:55 PM on January 15, 2012

"BUT, it's not like the elevation data will suddenly jump from one end of it's accuracy scale to the other …"

But it will jump around a hell of a lot - I'm looking at a dataset right now with 53m difference in altitude across ~100 consecutive samples taken 30 seconds apart at exactly the same spot on open flat ground, albeit with trees obscuring the horizon up to ~20°. The distribution is not exactly normal, but the 95% CI is 108m ±~24m.

By comparison, the horizontal location is varying by less than 1.2m across the same time.

That said, it's raw data from a bare GPS module - ideally, either the GPS or desktop software would do some low-pass filtering / smoothing to minimise the problem (and I'll do that, once I get the data from a device located at a reference site). And I don't know an easy way of getting better accuracy, short of using D-GPS or a suitably-calibrated and referenced aneroid barometer.
posted by Pinback at 5:38 PM on January 15, 2012

(Or barometric altimeter. I knew what I meant…)
posted by Pinback at 5:44 PM on January 15, 2012

Topofusion is what folks that mountain bike like to use.
posted by alex_skazat at 7:35 PM on January 15, 2012

Response by poster: Thanks for these recommendations. I looked at topofusion, which dies exactly what I want, but is also $70.00 which is more than I can justify for idle curiosity. And its English maps are not that great.

Incomparably the best maps for England and part of Europe come with ViewRanger, which will also show the Ordnance Survey height data as well as the GPS when it analyses a track. They track each other quite well, but there is always a huge difference. On the other hand, it is impossible to look at only segments of a track in ViewRanger.

I will have a look at GPS Visualiser, and report.
posted by alloneword at 2:37 AM on January 16, 2012

Best answer: RideWithGPS does all you ask (upload a .gpx file, view on a map, zoom in on sections) for free.
posted by normy at 11:15 AM on March 29, 2012

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