CODEWITHSUNDEEP
androidorientationaugmented-realitysensorscompass-geolocation
Adrian Eb
Adrian Eb

Reputation: 111

Android: Problems calculating the Orientation of the Device

i'am trying to build a simple Augmented Reality App, so I start working with sensor Data.

According to this thread (Android compass example) and example (http://www.codingforandroid.com/2011/01/using-orientation-sensors-simple.html), the calculation of the orientation using the Sensor.TYPE_ACCELEROMETER and Sensor.TYPE_MAGNETIC_FIELD doesn't really fit.

So I'm not able to get "good" values. The azimut values doesn't make any sense at all, so if I just move the Phone upside the value changes extremly. Even if I just rotate the phone, the values doesn't represent the phones orientation.

Has anybody an idea, who to improve the values quality according to the given example?

Upvotes: 11

Views: 22421

Answers (5)

Chris Sprague
Chris Sprague

Reputation: 3574

Here's a Kotlin approach with all the necessary matrices included (for some reason the previous answers leave out the array sizes, which matter)

// This is determined from the deprecated Sensor.TYPE_ORIENTATION
var lastOrientation: FloatArray = FloatArray(3)
var lastHeading: Float = 0f
var currentHeading: Float = 0f

// This is from the non deprecated Sensor.TYPE_ROTATION_VECTOR
var lastVectorOrientation: FloatArray = FloatArray(5)
var lastVectorHeading: Float = 0f
var currentVectorHeading: Float = 0f

override fun onSensorChanged(event: SensorEvent) {
    when(event.sensor?.type) {
        null -> return
        Sensor.TYPE_ORIENTATION -> {
            lastOrientation = event.values
            lastHeading = currentHeading
            currentHeading = abs(event.values[0].roundToInt().toFloat())
        }
        Sensor.TYPE_ROTATION_VECTOR -> {
            lastVectorOrientation = event.values
            lastVectorHeading = currentVectorHeading

            val tempRotationMatrix = FloatArray(9)
            val tempOrientationMatrix = FloatArray(3)
            getRotationMatrixFromVector(tempRotationMatrix, event.values)
            remapCoordinateSystem(tempRotationMatrix, AXIS_X, AXIS_Z, tempRotationMatrix)
            getOrientation(tempRotationMatrix, tempOrientationMatrix)
            currentVectorHeading = Math.toDegrees(tempOrientationMatrix[0].toDouble()).toFloat()
            
            if(currentVectorHeading < 0) {
                currentVectorHeading += 360f//heading = 360 - abs(neg heading), which is really 360 + (-heading)
            }
        }
        else -> return
    }
}

I've also included the deprecated Sensor.TYPE_ORIENTATION for anybody wanting to see the difference between the two approaches. There is a several degree difference when using the deprecated method vs the updated approach.

Upvotes: 0

Thibaud Michel
Thibaud Michel

Reputation: 353

Answer from Tíbó is good, but if you log roll value, you will expect irregular numbers. (roll is important for AR Browsers)

This is due to 

SensorManager.remapCoordinateSystem(mRotationMatrix,
                    SensorManager.AXIS_X, SensorManager.AXIS_Z,
                    mRotationMatrix);

You have to use different matrix for in and out of remap. This following code works for me with a correct roll value:

@Override
public void onSensorChanged(SensorEvent event)
{
    // It is good practice to check that we received the proper sensor event
    if (event.sensor.getType() == Sensor.TYPE_ROTATION_VECTOR)
    {
        // Convert the rotation-vector to a 4x4 matrix.
        SensorManager.getRotationMatrixFromVector(mRotationMatrixFromVector, event.values);
        SensorManager.remapCoordinateSystem(mRotationMatrixFromVector,
                    SensorManager.AXIS_X, SensorManager.AXIS_Z,
                    mRotationMatrix);
        SensorManager.getOrientation(mRotationMatrix, orientationVals);

        // Optionally convert the result from radians to degrees
        orientationVals[0] = (float) Math.toDegrees(orientationVals[0]);
        orientationVals[1] = (float) Math.toDegrees(orientationVals[1]);
        orientationVals[2] = (float) Math.toDegrees(orientationVals[2]);

        tv.setText(" Yaw: " + orientationVals[0] + "\n Pitch: "
                + orientationVals[1] + "\n Roll (not used): "
                + orientationVals[2]);

    }
}

Upvotes: 15

Jean-Paul Kouma
Jean-Paul Kouma

Reputation: 243

Probably late to the party. Anyway here is how I got the azimuth

private final int sensorType =  Sensor.TYPE_ROTATION_VECTOR;
float[] rotMat = new float[9];
float[] vals = new float[3];

@Override
public void onSensorChanged(SensorEvent event) {
    sensorHasChanged = false;
    if (event.sensor.getType() == sensorType){
        SensorManager.getRotationMatrixFromVector(rotMat,
                event.values);
        SensorManager
                .remapCoordinateSystem(rotMat,
                        SensorManager.AXIS_X, SensorManager.AXIS_Y,
                        rotMat);
        SensorManager.getOrientation(rotMat, vals);
        azimuth = deg(vals[0]); // in degrees [-180, +180]
        pitch = deg(vals[1]);
        roll = deg(vals[2]);
        sensorHasChanged = true;
    }
}

Hope it helps

Upvotes: 9

T&#237;b&#243;
T&#237;b&#243;

Reputation: 1218

In what kind of orientation do you use this sample app? From what is written is this code, the only orientation supported is Portrait or flat on the table, it depends on devices. What do you mean by "good"?

It is normal that the value is not "good" when rotating the device, the device coordinate system is supposed to be working in Portrait, or flat i don't know (Y axis vertical along the screen pointing up, Z axis pointing out of the screen coming from the center of screen, X axis perpendicular to the Y axis going on the right along the screen). Having this, rotating the device will not rotate the device coordinate system, you'll have to remap it.

But if you want the heading of the device in Portrait orientation, here is a piece of code that works good for me:

@Override
public void onSensorChanged(SensorEvent event)
{
    // It is good practice to check that we received the proper sensor event
    if (event.sensor.getType() == Sensor.TYPE_ROTATION_VECTOR)
    {
        // Convert the rotation-vector to a 4x4 matrix.
        SensorManager.getRotationMatrixFromVector(mRotationMatrix,
                event.values);
        SensorManager
                .remapCoordinateSystem(mRotationMatrix,
                        SensorManager.AXIS_X, SensorManager.AXIS_Z,
                        mRotationMatrix);
        SensorManager.getOrientation(mRotationMatrix, orientationVals);

        // Optionally convert the result from radians to degrees
        orientationVals[0] = (float) Math.toDegrees(orientationVals[0]);
        orientationVals[1] = (float) Math.toDegrees(orientationVals[1]);
        orientationVals[2] = (float) Math.toDegrees(orientationVals[2]);

        tv.setText(" Yaw: " + orientationVals[0] + "\n Pitch: "
                + orientationVals[1] + "\n Roll (not used): "
                + orientationVals[2]);

    }
}

You'll get the heading (or azimuth) in:

orientationVals[0]

Upvotes: 24

Streets Of Boston
Streets Of Boston

Reputation: 12596

Have you tried the combined (sensor-fusion) type Sensor.TYPE_ROTATION_VECTOR. This may give better results: Go to https://developer.android.com/reference/android/hardware/SensorEvent.html and search for 'rotation_vector'.

Upvotes: 0

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