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Understanding elevations in Tracks

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  • #7238
    BuckyEBuckyE
    Moderator
    • Topics: 61
    • Replies: 286

    Which I obviously don’t! Loie and i did this hike a month ago and it almost killed us. Took us close to seven hours: we were going up and down and up and down the whole way!

    So, can someone tell me what the numbers mean? I can’t make them add up and don’t know what they mean, except that I suspect the Ascent and Descent figures tell me we were going to do a lot of up and down?

    Thanks!

    enter image description here

    #7239
    jsgblomjsgblom
    Moderator
    • Topics: 84
    • Replies: 239

    Ascent and Descent are the cumulative of going up and downhill. Alt Change = Ascent – Descent.

    When altitude and time is included in the track PE will show a graph with the profile. You can find this at the bottom of the Detail screen. Tapping the graph will show it full screen. It shows a graph of the total track and also of each segment if applicable.

    When your track does not have both time and elevation you can add it using the excellent web app mygpsfiles:
    • go to http://mygpsfiles.com/app/
    • open the gpx track (Track » Open…)
    • open the toolbox (Window » Toolbox)
    • select the tab Elevation, select Use elevation from Mapquest and press the Apply button
    • select the Time tab and select Set speed to the average speed, press the Apply button
    • save the file by clicking the old-fashioned floppy disks somewhere top left.
    • import this saved file into PE and viola you have a profile.

    mygpsfiles.com/app bonus tips:
    • click on the profile and hover the mouse along the profile.
    • switch the map to Earth 3D (top right corner) and wait for the Google Earth plugin to start (if installed on your computer)
    • you can also open multiple tracks and merge into one, so you have only one file in PE

    #7240
    jsgblomjsgblom
    Moderator
    • Topics: 84
    • Replies: 239

    BTW: When editing it in mygpsfiles its wise to keep a back up of the original track or maybe even better (and easier) to save it with a different name, indicating that it has alt+time added to it.

    #7241
    BuckyEBuckyE
    Moderator
    • Topics: 61
    • Replies: 286

    Dear jsgblom,

    Holy Moses! I never even knew all this! Can’t thank you enough. How do you folks find out all this stuff about PE? Neato!

    Coincidentally, this Track is the only one I saved that had a Profile. See below. So, now I have to see some Tracks that have a relatively level course, for comparison, because I’m not familiar with reading Profiles. I’m familiar with looking at topo lines and shaded relief to get a general idea of the amount of up&down. This one looks like there’s a lot of up&down, and I know there was, but “reading” a Profile in detail will take some experience!

    Ah, I see my problem with these “cumulative” numbers as a gauge of the difficulty of the hike. They are cumulative for what I’ll call “overall elevation.” They don’t tell me how many actual feet of elevation we walked up, or down. Hah! Even when the overall trend may be down, there are still a lot of up spikes on this track. And vice versa. Interesting! So, in general, the numbers are a start, but the Profile is the secret.

    There are some oddities in this Track: the graph seems to begin and end at 1,000 feet, not 666. Because it’s supposed to be a circuit hike (beginning and ending at the same place), it should have no Alt Change at all; but I don’t know who recorded it or how. So I don’t think this is a good example for study, but it’s the one I have, and I see the principle.

    Now I have to mygpsfiles.com a couple of Tracks, and compare Profiles. Thank you so much for all your help!

    Yours truly,
    Bucky

    Circuit hike around Pic St. Loup

    #7257
    jsgblomjsgblom
    Moderator
    • Topics: 84
    • Replies: 239

    My pleasure!

    On the left Side of the graph I see a vertical orange line going down. This causes the 666-1000ft gap I reckon.

    Btw, you can overwrite the recorded altitude with mygpsfiles. A nice way to compare the two.

    Regards,
    • Johan

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