Hi Guys I am creating some sample Compass app and I am having some issues
on developing the app.Firstly i am not sure whether I am calculating eh
values correctly and secondly it seems like a lot of jittering is
happening.. I am attaching the source code below.Can you help me on steps I
need to perform
package net.test.example.compass;
import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
public class CompassExample4Activity extends Activity implements
SensorEventListener{
private SensorManager mSensorManager;
CompassView mCompassView;
Sensor accelerometer;
Sensor magnetometer;
float azimut;
float[] mGravity;
float[] mGeomagnetic;
static final float ALPHA = 0.2f;
double SmoothFactorCompass = 0.5;
double SmoothThresholdCompass = 30.0;
double oldCompass = 0.0;
int oldCompass2 = 0;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mCompassView = new CompassView(this);
//this.setRequestedOrientation(0);
setContentView(mCompassView);
mSensorManager = (SensorManager)getSystemService(SENSOR_SERVICE);
accelerometer =
mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
magnetometer =
mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
}
@Override
public void onResume() {
super.onResume();
mSensorManager.registerListener(this, accelerometer,
SensorManager.SENSOR_DELAY_UI);
mSensorManager.registerListener(this, magnetometer,
SensorManager.SENSOR_DELAY_UI);
}
@Override
public void onPause() {
super.onPause();
mSensorManager.unregisterListener(this);
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
// TODO Auto-generated method stub
}
@Override
public void onSensorChanged(SensorEvent event) {
// TODO Auto-generated method stub
if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
mGravity = lowPass(event.values, mGravity);
if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD)
mGeomagnetic = lowPass(event.values, mGeomagnetic);
if (mGravity != null && mGeomagnetic != null) {
float R[] = new float[9];
float I[] = new float[9];
boolean success = SensorManager.getRotationMatrix(R, I, mGravity,
mGeomagnetic);
// Correct if screen is in Landscape
SensorManager.remapCoordinateSystem(R, SensorManager.AXIS_X,
SensorManager.AXIS_Z, R);
if (success) {
float orientation[] = new float[3];
SensorManager.getOrientation(R, orientation);
float azimut = orientation[0]; // orientation contains: azimut,
pitch and roll
//float azimuth = (float)
Math.round((Math.toDegrees(orientation[0]))*7)/7;
//azimuth = ( azimuth + 360)%360;
mCompassView.updateDirection((float)smoothnessFunction(azimut*360/(2*3.14159f)));
//mCompassView.updateDirection(azimuth);
}
}
}
protected float[] lowPass( float[] input, float[] output ) {
if ( output == null ) return input;
for ( int i=0; i<input.length; i++ ) {
output[i] = output[i] + ALPHA * (input[i] - output[i]);
}
return output;
}
public double smoothnessFunction( double newCompass) {
if (Math.abs(newCompass - oldCompass) < 180) {
if (Math.abs(newCompass - oldCompass) > SmoothThresholdCompass) {
oldCompass = newCompass;
}
else {
oldCompass = oldCompass + SmoothFactorCompass * (newCompass -
oldCompass);
}
} else {
if (360.0 - Math.abs(newCompass - oldCompass) > SmoothThresholdCompass)
{
oldCompass = newCompass;
} else {
if (oldCompass > newCompass) {
oldCompass = (oldCompass + SmoothFactorCompass * ((360 +
newCompass - oldCompass) % 360) + 360) % 360;
} else {
oldCompass = (oldCompass - SmoothFactorCompass * ((360 -
newCompass + oldCompass) % 360) + 360) % 360;
}
}
}
return oldCompass;
}
public int smoothnessFunction2(double newCompass){
if ((int)newCompass % 360 != oldCompass2) {
oldCompass2 = (int) newCompass;
}
return oldCompass2;
}
}
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