Compass auto-calibration

2012-08-13
2013-05-29
  • Jyrki Kuoppala

    Jyrki Kuoppala - 2012-08-13

    from sk750

    --

    I also wondered about autocalibration - what is it doing exactly?

    Does it use some heuristic e.g. 3 consecutive GPS courses being the same?

    Does it remember the course correction based on that permanently?

    I also noticed that being close to metal elements which might be in a car,
    irritated the compass, so auto-calibration might be no good idea by
    default.

    Well, maybe these questions would rather be something for the wiki faq /
    documentation.

     
  • Jyrki Kuoppala

    Jyrki Kuoppala - 2012-08-13

    It uses the same heuristic as the normal movement rotation.

    The deviation is not remembered across reboots, and the idea is that auto-calibration will happen often.

    The influence of metal to compass direction was actually one motivation for the auto-calibration function. Assuming the influence of metal keeps the same, auto-calibration will compensate against it. As it's expected auto-calibration will happen often (always when there's movement enough to trigger movement-based rotation), so it shouldn't be a problem if different calibration is needed for walking and driving.

     
  • sk750

    sk750 - 2012-08-13

    I'd rather keep this of by default, might be irritating that when not enough movement happens when leaving the car the compass goes wrong because of metal in the car or parking backwards.

     
  • Jyrki Kuoppala

    Jyrki Kuoppala - 2012-08-13

    Switched the default off for now.

    We should have an ordinary compass needle display on the map, then it would be easy for the user to see if compass direction is different from map rotation. With no compass needle, it can be hard to understand deviation. Compass is not on by default, so in principle compass settings are easily visible when switching compass rotation on, but in practice they will probably often be ignored as they're under a different heading than rotation (compass activation).

     
  • Jyrki Kuoppala

    Jyrki Kuoppala - 2012-08-13

    Compass needle could also be used with a warning color such as yellow to indicate need for calibration by waving in an 8-shape.

    Auto-calibrating rotation by compass should also have some kind of visual information. Also, perhaps under the heading letter could have a small compass icon to indicate rotation by compass alone, a somehow higlighted icon to indicate rotation by compass plus deviation, possibly also optionally show the deviation.

     
  • sk750

    sk750 - 2012-08-13

    Would be also nice to indicate where the course comes from e.g. use a green instead of yellow background for the current point of compass, when the course comes from the compass. But that would be if done right another colors.inc entry which we unfortunately neglected recently for some other things like transparent buttons/distance background.

    Single tapping the map might also show the other (currently not used) point of compass as well below the used one.
    E.g. when course from GPS is NWW and course from compass is N:
    - when moving: top compass is yellow, showing NWW, map rotated to NWW, lower compass is green showing N
    - when not moving: top compass is green, showing N, map rotated to N, lower compass is green showing NWW
    - when compass is off or not available: everything is like it is now

     

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