CODEWITHSUNDEEP
androidandroid-sensors
Bart Friederichs
Bart Friederichs

Reputation: 33491

Get orientation in degrees

I am trying to create a simple compass app (for learning purposes) and I am using the rotation matrix using the magnetic sensor and accelerometer. This is my code:

@Override
public void onSensorChanged(SensorEvent event) {
    if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) {
        geomagnetic[0] = event.values[0];
        geomagnetic[1] = event.values[1];
        geomagnetic[2] = event.values[2];
        havemag = true;
    }
    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
        gravity[0] = event.values[0];
        gravity[1] = event.values[1];
        gravity[2] = event.values[2];
        haveacc = true;
    }

    if (haveacc && havemag) {
        if (SensorManager.getRotationMatrix(Rm, I, gravity, geomagnetic)) {
            float[] result = new float[3];
            SensorManager.getOrientation(Rm, result);

            azimuth = result[0];
            pitch = result[1];
            roll = result[2];
        }
    }
}

When I look at these values while moving my phone though (outputing using Log.d), I get incorrect values. I use this code to make degrees out of them:

int deg = (int)(azimuth * (float)57.295);

But this value never reaches zero (which is supposed to be on the exact opposite side of 180/-180). Instead, the opposite of where 180/-180 is, I get -85 (approx).

Upvotes: 2

Views: 5302

Answers (1)

Rubberducker
Rubberducker

Reputation: 1137

You should use the proper JavaMath function to convert your radian angle to degree. Furthermore converting the angle (in degree) to a [0 - 360] degree interval is very useful.

// angle in degree [-180 - 0 - 180] degree
azimuth = Math.toDegrees( result[0] )

// angle in degree [0 - 360] degree
azimuth = ( Math.toDegrees( result[0] ) + 360 ) % 360;

Upvotes: 7

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