GPX files
Original post
Hi everybody. I have GPX file upload and sharing back online. I have also improved how GPX files are displayed somewhat.
Note that a bot is working in the background to extract meta data from all the files and it should be finished sometime later today. The meta data appears to the right of the map if available.
Please let me know if you have any queries about the accuracy of the meta data. For this track http://tramper.co.nz/?8007 for example the gradient reaches 89 degrees. I'm not sure what this relates to on the ground! There is a lot of variation in the markup of GPX files and interpreting that information is a challenge. If there is anything else you would like to see (e.g. name of generating device) or anything you think is useless let me know.
I am wondering if an average gradient might be interesting. It could be a good indicator? Note this would be average unsigned gradient -- don't want the downhills cancelling the uphills!
These will be added in future:
* Elevation profiles of routes.
* Automatically filling in the "locations" field for the file. Note that it is a good idea to supply at least one point in this field as it is used when browsing the map or searching. I will automate this at some stage.
* integrating GPX data into views of tracks.
15 comments
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Page: 12
Hi Matthew, also, have a look at http://tramper.co.nz/?6988. Aspiring – Ress gpx. It is a combination of map-drawn tracks, created in 2008 and edited in 2010. The calculated time is -16,782 hrs (your calculation and OziExplorer – note that’s negative time :) or 22,120+ days (in Basecamp).
There is potential for distance errors too – but I think that may be less of an issue than time. If spurious points (from signal loss or satellite error or whatever) are edited out, the distance will become more accurate. If the spurious points are not edited out, they will at least be visible on the map (and the bigger the error, the more visible).
BTW, recently near 3 Tarns Pass, I turned on the GPS and noticed that the position was well to the east of my actual position. I gave it a few minutes to reconsider but it settled down just over 2km away. Puzzled, I turned the GPS off and back on (no, it’s not a Windows O/S ! it’s a Garmin) and it correctly located itself.
Another transient error occurred some months ago when in the Grampians, I turned on the GPS (track-logging was on) and the first point logged was in the Flinders Ranges (700km away!) That certainly impacted the total distance recorded !
I get 23:22 as well which is clearly wrong. However, for many others I've looked at the times are about right and seem useful. I feel the best way to address this is with wording: to change "total time" to "recorded time". Then you can make your own judgement about whether that recording is accurate. Another option could be to remove sections that are very slow or stopped. But that could be a challenge given the issues Izogi raises.
BTW I note that all the files seem to record one trkseg block only, even though they can have any number. I suspect files with two disconnected lines will record two trkseg blocks.
I have tweaked the file scraping, and it is currently half way through updating them all.
BernieQ, your Aspiring--Rees file jumps around in time. I think it would make sense to simply discard the time data if any points are out of order. I can do that easily.
I feel the best way to address this is with wording: to change "total time" to "recorded time".
Matthew, that's an elegant solution - well done!
When I load GPX tracks I usually try and edit out the anomalies. I also join or cut tracks into logical units, ie Day1, day2 etc. I also ALWAYS thin out the track so that no track is greater than 500 points. Usually making 1 point every 30m does the trick. The reason for 500 points in that if I load a track greater than 500 points into my Garmin 60CSX it will TRUNCATE the track to 500 points. That could be disastrous if you load up a 2000 point track and expect it all to be there and then find out in the field that it ends a quarter of the way through your trip.
Also by thinning out the track you usually remove silly bits, like a great nest of points where you sat down and had lunch. I suspect an edited track like this is going to produce more accurate statistics as well.
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| Started by | matthew |
| On | 25 April 2013 |
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