Adventurer altitude calculations — TomTom Community

Adventurer altitude calculations

coljaycoljay Posts: 3 [Apprentice Traveler]
edited January 2019 in TomTom Adventurer
Has anybody figured out how the altitude function on the new Adventurer works yet?

I can see, on a relevant activity setting such as hiking, display options for two different altitude data items. It's not clear to me what the two are.

Further, given that the altitude data is partly (substantially?) dependent on barometric information, I can't find any way of calibrating or zeroing that.

There was no manual in the box, of course, and the support pages are linking an old manual. The pdf you get doesn't refer to the new products (I've emailed support about that).

Anybody got it sussed?

Comments

  • tfarabaughtfarabaugh Posts: 16,344
    Superusers
    coljay wrote:
    Has anybody figured out how the altitude function on the new Adventurer works yet?

    I can see, on a relevant activity setting such as hiking, display options for two different altitude data items. It's not clear to me what the two are.

    Further, given that the altitude data is partly (substantially?) dependent on barometric information, I can't find any way of calibrating or zeroing that.

    There was no manual in the box, of course, and the support pages are linking an old manual. The pdf you get doesn't refer to the new products (I've emailed support about that).

    Anybody got it sussed?

    The barometric altimeter calibrates itself to GPS at the beginning of the run. The relevant metrics are the current elevation, the elevation delta, the grade % and the total climb. I have checked the current elevation against known points during a run and it has been pretty spot on, but you can get variations due to weather and other factors as it is a barometer. The delta (the difference between where you are and the starting point) is also fairly accurate. The grade % has a small lag (5-10 seconds) and seems fairly accurate (no way to tell but it seems to match what I expect) and the cumulative climb is fine. Bear in mind that since it is a barometer, it is going to pick up every elevation change, even tiny ones, unlike one based on a Digital Elevation Model, which factors out immaterial changes. They are actually tweaking this a bit to bring them closer together I think. You will also get a more accurate (and generally longer) distance with a barometric watch as it is calculating 3d distance, to 2d, so it picks up the added distance on climbs.

    I hope this helped answer your question. If so, please mark it as a solution so others can look for it if they have the same question.
  • coljaycoljay Posts: 3 [Apprentice Traveler]
    Many thanks for the info.

    I'll be interested to see how well the calibration works at the beginning of an activity as that must be dependent upon gps and gps isn't that great at determining altitude (that, after all, being the point of adding the barometric tools). I've used handheld units in the past that required either a known spot height, or a pressure reading, to be entered for calibration.

    I was testing other aspects of the watch today. All good so far.
  • gl00gl00 Posts: 965 [Revered Pioneer]
    coljay wrote:
    Many thanks for the info.

    I'll be interested to see how well the calibration works at the beginning of an activity as that must be dependent upon gps and gps isn't that great at determining altitude (that, after all, being the point of adding the barometric tools). I've used handheld units in the past that required either a known spot height, or a pressure reading, to be entered for calibration.

    I was testing other aspects of the watch today. All good so far.

    yup, you're right, GPS is not great for altitude... but it gets better over time (during the activity).
    what you get is a rough estimate of your absolute altitude for the beginning of your activity (within +/- 30m of actual altitude), BUT the watch keeps calibrating over time (when it gets a better signal) and it gets more accurate after a few minutes.

    if the signal is good enough (blue sky, open field), I can get accuracy down to the meter pretty quick... but if conditions are bad (dense trees, many clouds...), it can remain within 10-30m of the actual altitude... it all depends on the conditions... (checked with national survey maps in France, went as far as checking altitude in front of the markers used for the survey :P )

    Note that thanks to the barometer, all relative data (cumulated climb, slope %, altitude delta...) are always as good as can be and the altitude profile is correct: you won't see crazy changes of altitude due to the calibration phases.

    as far as I'm concerned, it's a lot easier than having to calibrate manually and more efficient and gives results that are good enough... just don't trust absolute altitude too much, especially at the beginning of an activity
  • reethreeth Posts: 1 [Apprentice Traveler]
    I'm afraid that I have some problems with the altitude calculations on my watch.

    This week I went to the snow and each day my max gradiënt was + 100%. One day, it was even 200%.

    Back home, I went walking under sea level and when I play tennis or football, I can be on 2m or on 6m on the same pitch...

    Can this be more accurate?
  • PhilippeCHPhilippeCH Posts: 3 [Apprentice Traveler]
    I also had the same problem, eventually I discovered that the hiking option did offer data on altitude and altitude delta, you can choose to display this data on your metric screen to check at a glance your altitude when walking.
    This function does not seem to exist with other options like cycling, which is annoying as when cycling you also want to know your altitude, simply to know how many more metres you need to climb, if you head for the top of a hill for instance. As a result I continue using my Garmin edge 520 which offer this option, although I have to say that the navigation in the Tomtom adventurer is extremely user friendly. By the way it is interesting to note that data on distance , height etc.. does not match between Garmin and TT Adventurer????
    and last a question how do you guys check the altitude when cycling?? do you get out of the cycling option into the hiking to check altitude? if you do so can you get back into into thee cycling option and continue your ride without having lost the previous history??
  • tfarabaughtfarabaugh Posts: 16,344
    Superusers
    Garmin recalculates the elevation data based on the GPS points using a digital elevation model, it ignores the barometer data, which is why they don't match.
  • gl00gl00 Posts: 965 [Revered Pioneer]
    PhilippeCH wrote:
    how do you guys check the altitude when cycling?? do you get out of the cycling option into the hiking to check altitude? if you do so can you get back into into thee cycling option and continue your ride without having lost the previous history??

    alas, altitude is not a data available in Cycling mode. What I do is use Freestyle instead, and then change the activity type in Mysports. the most notable difference between these 2 modes is that there is no connection to speed/cadence sensor possible in Freestyle mode...

    you cannot get out of a mode without stopping the activity.
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