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Issue: speed tag is m/s
#1
Hello,

GPX file format, speed tag seems to generally be m/s. RouteConverter displays it as km/h without converting it Smile

Hope this can be fixed!
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#2
I have a trip that is almost 8 hours long, and averages 80.5 km/h for the duration of the trip, once I remove all of the stops, including an overnight stop at a motel. I take the distance traveled and the number of positions, recorded at one per second, and get the average speed. 80.5 km/h, which works out to 22 meters per second, as there are 3600 seconds in an hour [60*60], and 80500 meters traveled in that hour.

However I do NOT see 22 km/h as having been calculated in my file... Lots of 70-120 km/h on expressways and 40-70 km/h on the rest of the roads... so at least with my ASUS R300 and RouteConverter I do NOT see m/s instead of km/h, and the values are indeed computed correctly.
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#3
Hm, there's always a possibility, that different devices log differently. Does yours log directly to GPX or do you use some software to convert it?

BT747 team has told me, and from what I've gathered on internet, that correct way to mark speed in GPX is using m/s (though apparently GPX specification doesnt document that tag at all, it's lax declaration..)

Perhaps there should be an option then?[/align]
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#4
The ASUS R300 GPX file contains date, time, lat and long only, with a position noted every second. RouteConverter calculates the speed for me. It logs a shorter form and uses an internal computation and export to write the GPX file on the microSD card from the flash memory in the unit itself, which is where the track is stored. So the GPX does NOT have speed in it until I have RouteConverter compute it. In my case I have NO use for m/s as that would then have to be converted to km/h to be useful for my uses, since speed limits are km/h in Canada and the unit displays my speed in mph or km/h depending on which side of the Canada-U.S. border I'm on at the time.
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#5
Aha, so that's it! It does not contain speed, so it depends on RC to calculate it. Which does not contradict my statement, that internally it should store m/s (though I have to agree, that for display km/h is much more useful)
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#6
(02.07.2009, 07:45)mrQQ Wrote: Aha, so that's it! It does not contain speed, so it depends on RC to calculate it. Which does not contradict my statement, that internally it should store m/s (though I have to agree, that for display km/h is much more useful)

If, after I loaded one or more files, edited them, added speed, and then saved them for use elsewhere, it saved the speed as m/s AND I then looked at the file in the 'other' program or worked with it as a comma delimited file, I would have to manually convert from m/s to km/s and would be most unhappy. I can read my file in wordpad or any word processor since it is a text file when all is said and done, and m/s would ruin the whole exercise for my purposes. Give me km/h or mph [and I already know Christian will not do the latter] or give me a registry setting where I can select km/h but do NOT give me m/s... as I am not a 100 meter track runner, where that number has meaning <grin>... I should like to see anything that absolutely states that speed should be stored as m/s. I did find that time has to be stored as Zulu time... but not that speed has to be stored as m/s [or that elevation/altitude has to be stored as meters and cannot be stored as feet above sea level - also appropriate in the U.S.].
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#7
(01.07.2009, 15:24)mrQQ Wrote: GPX file format, speed tag seems to generally be m/s. RouteConverter displays it as km/h without converting it Smile

Hope this can be fixed!

Hi mrQQ,

thank you for pointing that out. The GPX 1.0 manual clearly says:

Quote:<speed>
Optional in: <wpt> <rtept> <trkpt>
Units: meters per second
<speed>4.23</speed>
Instantaneous speed at the point.

Please try the latest prerelease which fixes this.
--
Christian
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#8
(02.07.2009, 02:26)RsH Wrote: I have a trip that is almost 8 hours long, and averages 80.5 km/h for the duration of the trip [..] I do NOT see m/s instead of km/h, and the values are indeed computed correctly.

Where is the speed stored? Within the <speed> element or with a comment?
--
Christian
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#9
(02.07.2009, 07:04)RsH Wrote: RouteConverter calculates the speed for me.

Hi Bob,

I should have read further... that calculation is based on Km/h, so everything should be fine. In GPX 1.0 there is a element for track points that uses m/s.
--
Christian
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#10
(02.07.2009, 13:51)routeconverter Wrote:
(02.07.2009, 07:04)RsH Wrote: RouteConverter calculates the speed for me.

Hi Bob,

I should have read further... that calculation is based on Km/h, so everything should be fine. In GPX 1.0 there is a element for track points that uses m/s.

Now I am using software where the company exports to GPX and exports the speed incorrectly as km/h so when I load it into RouteConverter the speeds are showing as impossible values, due to the difference between m/s and km/h.... Treat km/h as if it is m/s and the speed shown is well in excess of the speed limit <grin>. The OTHER GPS does NOT calculate speed, so RouteConverter does it and I can rely on its values... So is there a switch where I can say, treat this GPX as if it was right and uses m/s and threat this other GPX as if it is wrong and uses km/h?
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