.Map .gpx and how to analyse the obtained data

Nille · Occasional Visitor Joined: Mar 08, 2009 Posts: 2

Hello everyone,

New to the forum and new to having an Active 10. Been looking into getting one for months but didn’t actually take the plunge until last week. Had it out at the weekend for a lovely hike in the highlands and have to say that I am very impressed with the unit.

Now, back home, I find myself trying to get the most out of the data I collected but having some problems while doing so.

First of all I got a bit confused with the data files I collected during my trip. I first imported the track (converted from the trail I recorded during the walk) onto my computer and realised that this didn’t contain any other information than the name of each waypoint as well as the corresponding coordinates and elevation.It was missing time and date tags.
I also found a pretty large .gpx file (~3MB) on the Satmap which contains time/date. It seems to be named like the map file that I created just ends with “RAW.gpx”.
What surprises me here is that even though I stopped the trek log on the Active 10 at the end of the walk, this gpx file contains all the information of the journey home as well (until the point where I cleared the whole data). I don’t quite understand what the Active 10 is doing there. At which point is the .gpx file generated and why does the .map file not contain the full set of data while the .gpx file contains more than I want it to contain?

Anyway, nevertheless I tried to use the software package SportTrack to analyse the obtained data but even thought the software looked pretty good, I wasn’t able to give it a proper try as it kept crashing. So therefore I would like to ask you guys how you are analysing your data? Can you recommend some software that can do things like giving average speed, top speed, etc.? It would also be great if it could plot me things like speed over change in altitude, ascent/descent over time and remove parts of the recorded data (e.g. in case its been recorded for too long).

Your help is much appreciated.

Cheers,
Nils

Gibbo10 · Posted: Mon Mar 09, 2009 12:18 am Post subject:

Welcome to the forum.

As your satmap continued to record the route after you stopped it, I would think that it was shipped with the old version of the software. The latest version of the software does stop the recording of the data. But if you move to a new location and press start again it will draw a straight line between the two points.

You can upgrade quickly by downloading the updater from the satmap website and your problem should be fixed, there are some other great enhancements in the release as well.

The map file is just the format that sat map uses and as far as I can tell it's not used any where else satmap converts gpx files you import to it to .map files. The standard file type is .gpx satmap records two a basic one and a raw one, the raw one contains all the important data.

You could try http://www.gpsvisualizer.com/ to convert the file into either a plain text file that you can import into excel for your own analysis or you can get it draw a profile graph or convert it to a google earth file.

I have just started using Quo Pro - here you can import the route and get a route card drawn up.

I'm sure that the other forum users will be able to provide some more good ideas.

jonesbach · Regular Visitor Joined: Jun 07, 2008 Posts: 185

How comfortable are you preparing javascript/html and using your own site? If competent I can give you the routines I use on my own site which you can use as is or modify for your purpose, they are not perfect but they are usable. If not, and you can't get enough data for the moment on the site and methods Gibbo10 has suggested, short term/no charge I am prepared to host a page for you - one page at a time, perhaps once a fortnight would not be too onerous. It would give you total distance, average speed, a 1:50000 map with route and ability to select points and display data.

A few things to bear in mind on the limits of gps.

I am currently plotting an altitude profile but depending on topography this can vary from good to an unreadable mess. I did have similar ideas but have put it to bed pending more stable readings.

As you have found the files are large and they have to be compacted. Loading is still slow and a certain amount of data lost.

Nille · Occasional Visitor Joined: Mar 08, 2009 Posts: 2

Thanks for the replies you two.

@ Gibbo10: Thanks for the suggesting GPSVisualizer. I have used this site before but never realised that I could also just export it into a text file. The idea of exporting it into Excel is quite appealing because it would give me a great degree of freedom on how to analyse the software. However, I was hoping I could get some sort of stand alone software that would be specifically tailored to GPS systems to get it all a bit more “user friendly”. When saying “user friendly” I mostly refer to the way you would handle all the data. I kind of like the idea of SportTrack that it organises all of your activities, rather than just having individual gpx files in a few folders.

@jonesbach: Thank you for the very kind offer but I don’t think that implementing the whole idea into a website is the way to go for me. Theoretically the idea of implementing everything into one webpage is very appealing but I know that this would just be the start of a project that I wouldn’t be able to incorporate into my time schedule at the moment.
I am also aware of the associated problems of making conclusions out of the speed and altitude data that is recorded by the gps. I would really only use it to analyse smaller parts of a walk, which would reduce the amount of data significantly and thereby make judgement on the credibility easier.

As for the problem I faced with the data being logged passed the end of the hike:

I think what happened is the following. I stopped the logging after we finished the walk. I then converted the trail to track, assuming that this would dump all the data of the log into a file together with the actual route. I then, on the way home, switched the started the logging again, assuming that it would write the new data into a new file. Please correct me if I am wrong but I have the impression than rather than starting a new file it just added it to the RAW.gpx file that already existed.
Now is that always this way, or was it maybe because I had my originally route still set to active? If I deactivate the route, or start another one, will it then create a second “RAW.gpx” file?

Thanks again for taking your time to help.

Cheers,
Nils

jonesbach · Regular Visitor Joined: Jun 07, 2008 Posts: 185

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