Android Compass orientation on unreliable (Low pass filter)

Posted by madsleejensen on Stack Overflow See other posts from Stack Overflow or by madsleejensen
Published on 2011-01-15T11:50:42Z Indexed on 2011/01/15 11:53 UTC
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Hi all

Im creating an application where i need to position a ImageView depending on the Orientation of the device. I use the values from a MagneticField and Accelerometer Sensors to calculate the device orientation with

SensorManager.getRotationMatrix(rotationMatrix, null, accelerometerValues, magneticFieldValues)
SensorManager.getOrientation(rotationMatrix, values);
double degrees = Math.toDegrees(values[0]);

My problem is that the positioning of the ImageView is very sensitive to changes in the orientation. Making the imageview constantly jumping around the screen. (because the degrees change)

I read that this can be because my device is close to things that can affect the magneticfield readings. But this is not the only reason it seems. I tried downloading some applications and found that the "3D compass" application remains extremely steady in its readings, i would like the same behavior in my application.

I read that i can tweak the "noise" of my readings by adding a "Low pass filter", but i have no idea how to implement this (because of my lack of Math).

Im hoping someone can help me creating a more steady reading on my device, Where a little movement to the device wont affect the current orientation. Right now i do a small

if (Math.abs(lastReadingDegrees - newReadingDegrees) > 1) { updatePosition() }

To filter abit of the noise. But its not working very well :)

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