[Interest] Questions about QtSensors and QCompass

[maitai]

Thanks Lorn for your reply,

Since then I have also tried on iOS and it works pretty well, with the 
exception that if the compass is not calibrated iOS is trying hard to 
show the calibration screen, but do not succeed and the result is that 
my app is flashing during a minute or 2 and then all is back to normal.

Is there a way to catch something like a "sensorNeedCalibration signal" 
and call automatic calibration if it exists? Or should I implement 
(BOOL)locationManagerShouldDisplayHeadingCalibration in iOS and try to 
find something similar for Android?

Philippe Lelong

Le 06-01-2016 23:50, Lorn Potter a écrit :
> Hi,
> 
> On 05/01/16 21:25, maitai wrote:
>> Hello,
>> 
>> I am trying to use QCompass sensor on Android and iOS.
>> 
>> It works well on Android (didn't test on iOS yet), but I have 
>> questions
>> regarding calibration:
>> 
>> The link in qt documentation is dead (
>> http://wiki.forum.qt.com/index.php/CS001671_-_Calibrating_the_magnetometer_sensor
>> ). Does anyone knows where to find it or can explain how to proceed to
>> calibrate the magnetometer? I tried to move the device in 8 figures 
>> and
>> such but that does not seem to improve anything.
>> 
>> I have two real devices. On the first one the north reported by the
>> sensor is more or less ok, but on the second one it is completely 
>> false
>> and not stable at all. Strangely both devices are reporting 0.0 as
>> calibrationLevel... is it normal?
> 
> It really depends on the device and the android version. I have seen
> some versions of sensors on android that had only a proprietary
> calibration routine hidden for that specific device that was not
> hooked up to the usual calibration gesture and no automatic
> calibration.
> I have also seen devices that take a long time to get calibrated (due
> to very (cheap) noisy magnetometers)
> 
> Then there is the issue with magnetic variance/deviation, and if it
> gets applied or not.
> 
> and on top of that, this all depends on local magnetic interferences
> like computers, metal objects and even components in the phone itself.
> :)
> 
> There are some android apps that will do compass calibration, but your
> mileage will vary on different devices.
> 
> Having a calibrationLevel of 0 or SENSOR_STATUS_UNRELIABLE means
> calibration is needed.
> 
> Hope this helps!
> 
> -
> Lorn
> 
>> 
>> Thanks for any insight
>> Philippe Lelong
>> 
>> 
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