Complete
over 4 years ago

Activity.Info.altitude uses barometric pressure for altitude and falls back to GPS altitude while Position.Info.altitude is GPS only.

Playing back fit file in simulator

I can't help myself, but info.object values do not match what I see in fit file (when viewing fit externally)

Even I take tcx file (so I can read it), convert it to fit, play it back in simulator I still see different values, esp for elevation (at least that's what I care about). These are not completely different values, it's like 50-100m off, but I see no reason why this is happening. Is it known behavior? 

jannk3
Parents
  • over 4 years ago in reply to subra

    I wrote:

    For my .fit e.g.
    Activity.Info.altitude = 14.397258 (wrong?)
    Position.Info.altitude = 32.592106 (seems to be correct and near at the value in .tcx)

    ----------

    The reason for the difference may be the initial value of Activity.Info.altitude = -17.998905

    Therefore it's calculated:
    Activity.Info.altitude = -17.998905 + 32.592106 ~ 14.397258
    Position.Info.altitude = 0.0 + 32.592106 = 32.592106

    The difference remains constant while replaying the .fit .

    @jannk3: Do you've also a constant difference?

Comment
  • over 4 years ago in reply to subra

    I wrote:

    For my .fit e.g.
    Activity.Info.altitude = 14.397258 (wrong?)
    Position.Info.altitude = 32.592106 (seems to be correct and near at the value in .tcx)

    ----------

    The reason for the difference may be the initial value of Activity.Info.altitude = -17.998905

    Therefore it's calculated:
    Activity.Info.altitude = -17.998905 + 32.592106 ~ 14.397258
    Position.Info.altitude = 0.0 + 32.592106 = 32.592106

    The difference remains constant while replaying the .fit .

    @jannk3: Do you've also a constant difference?

Children
  • over 4 years ago in reply to subra

    Honestly - I gave up on exploring what's exactly the difference. My data field app (number of ski lifts taken) seems to work fine on 3 fit files I recorded earlier this year despite those differences, I'm about to test it on real device soon now. Unfortunatelly it means 1 test = 1 day of skiing -> not many tests per year possible.

    But I can relate to your calculations - it matches with my observations, though I didn't took notes properly, so I can't confirm.