Hi,
Thanks for the explanation. It was very useful. I am trying to get 2
variables to store the lat/lon. Can we do that continuously? As in
have 3 variables. One each for current azimuth, Lat and lon. What
changes would we need to make in the code you provided here?
implementing LocationListener along with the this listener should do I
guess? But I tried and am unable to get both location and orientation
at the 'same time'.
thanks
Ricky
On Jun 17, 9:56 am, lawrizy <lawr...@gmail.com> wrote:
> Hi,
>
> I wanna thank you very much for your explanation. The official
> documentation was very difficult to understand. And the example in the
> api sample (the compass) does use a depreciated methods (with
> sensorlistener).
>
> I don't understand what does remapCoordinateSystem and his parameters,
> could you help?
>
> Thank you.
>
> On 16 juin, 06:28, "repDetect()" <n6mba50...@gmail.com> wrote:
>
> > Hi,
> > While trying to retrieve orientation data I found some pretty straight
> > forward code making use of SensorEventListener for
> > Sensor.TYPE_ORIENTATION and it works fine, but the
> > Sensor.TYPE_ORIENTATION constant has been deprecated recently - I
> > believe it was on 8 (API level) - which I understand to mean that
> > while I can still use it, I shouldn't.
> > The documentation [1] only says "use SensorManager.getOrientation()
> > instead." [2] but as a newbie, I had difficulties following that
> > "detailed" instruction.
>
> > So the question is:
> > How to properly get device orientation data?
>
> > In an attempt to make this discussion constructive, here is what I
> > managed to figure out, hopefully it will attract corrections relevant
> > to my limitations and not just general pointers to material I already
> > read (and misunderstood) and perhaps also benefit other newbies
> > struggling with this task.
> > So please fix any misconceptions or errors you find below.
>
> > The most important thing to realize is that
> > SensorManager.getOrientation() doesn't get the orientation from the
> > sensors (as with SensorEvent for Sensor.TYPE_ORIENTATION), it merely
> > "Computes the device's orientation based on the rotation matrix" which
> > you must provide as the first parameter.
> > In a similar fashion SensorManager.getRotationMatrix() doesn't read
> > sensors data to produce the rotation matrix, it depends on you to
> > provide the data through the third and forth arguments (gravity,
> > geomagnetic), also note that the values of these arguments must be
> > within expected limits or the method will fail. This holds in
> > particular for the case where these are initialized to zeros, as this
> > will imply free fall for gravity and something even more disturbing
> > for geomagnetic.
> > Don't take my word on it look it up for yourself in the source [3],
> > for the Java end at list.
>
> > Once that was digested it appears the only way to get sensor data is
> > through registering a sensor event listener (I thought it would be
> > really nice if I could query the sensors's readings at will and that
> > what I naively assumed was done by the get methods in SensorManager,
> > could anyone comment why this is not made available?), then that data
> > may be used to calculate the orientation as outlined below:
>
> > 1) Retrieve sensor data from accelerometer and magnetic field sensor
> > as required by getRotationMatrix():
> > This actually involves a number of steps in the Activity class:
> > 1.1) Obtain a sensor manager.
> > NOTE: Context.getSystemService needs a Context, typically called
> > within an Activity's context.
> > mSensMan = (SensorManager) getSystemService(SENSOR_SERVICE);
>
> > 1.2) Register a sensor event listener for each of the above sensor
> > types.
> > mSensMan.registerListener(this,
> > mSensMan.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),
> > SensorManager.SENSOR_DELAY_UI);
> > mSensMan.registerListener(this,
> > mSensMan.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
> > SensorManager.SENSOR_DELAY_UI);
>
> > 1.3) In the listener's onSensorChanged method copy the data from the
> > SensorEvent.values.
> > NOTE: The data must be copied off the event.values as the system is
> > reusing that array in all SensorEvents, simply assigning won't work.
> > public void onSensorChanged(SensorEvent event) {
> > switch (event.sensor.getType()) {
> > case Sensor.TYPE_ACCELEROMETER:
> > System.arraycopy(event.values, 0, mGravs, 0, 3);
> > break;
> > case Sensor.TYPE_MAGNETIC_FIELD:
> > System.arraycopy(event.values, 0, mGeoMags, 0, 3);
> > break;
> > default:
> > return;
> > }
>
> > }
>
> > 2) Pass the copied sensor data as arrays to
> > SensorManager.getRotationMatrix() to receive the rotation matrix.
> > SensorManager.getRotationMatrix(mRotationM, null, mGravs, mGeoMags)
>
> > Optionally transform the returned rotation matrix through
> > SensorManager.remapCoordinateSystem() or multiplying by a
> > transformation matrix.
>
> > 3) Pass the rotation matrix to SensorManager.getOrientation() to
> > receive the orientation as yaw, pitch and roll expressed in radians.
> > SensorManager.getOrientation(mRotationM, mOrientation);
>
> > Voila.
>
> > Below the relevant code is wrapped with a complete Activity to allow
> > for testing and to get the whole picture, once again - corrections and
> > remarks are requested - the TODO: tags would also indicate areas where
> > knowledge is lacking.
>
> > Please handle with care, this newbie is still a little wet and
> > slippery!
>
> > [1]http://developer.android.com/reference/android/hardware/Sensor.html#T...
> > [2]http://developer.android.com/reference/android/hardware/SensorManager...[],%20float[]%29
> > [3]http://android.git.kernel.org/?p=platform/frameworks/base.git;a=blob;...
>
> > <<------------------------------------------------------------------------------------------------------------------------
>
> > package my.odd.demo.orientation;
>
> > import android.app.Activity;
> > import android.hardware.Sensor;
> > import android.hardware.SensorEvent;
> > import android.hardware.SensorEventListener;
> > import android.hardware.SensorManager;
> > import android.os.Bundle;
> > import android.view.ViewGroup.LayoutParams;
> > import android.widget.TextView;
>
> > public class OrientationDemo extends Activity implements
> > SensorEventListener {
> > TextView mOrientationData;
> > private SensorManager mSensMan;
> > private float mAzimuth;
> > private float[] mGravs = new float[3];
> > private float[] mGeoMags = new float[3];
> > private float[] mOrientation = new float[3];
> > private float[] mRotationM = new float[9]; // Use [16]
> > to co-operate with android.opengl.Matrix
> > private float[] mRemapedRotationM = new float[9];
> > private boolean mFailed;
>
> > /** Called when the activity is first created. */
> > @Override
> > public void onCreate(Bundle savedInstanceState) {
> > super.onCreate(savedInstanceState);
>
> > // I'd like to actually see something so let's have a view:
> > mOrientationData = new TextView(this);
> > setContentView(mOrientationData, new
> > LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
>
> > // Initiate the Sensor Manager and register this as Listener for
> > the required sensor types:
> > // TODO: Find how to get a SensorManager outside an Activity, to
> > implement as a utility class.
> > mSensMan = (SensorManager) getSystemService(SENSOR_SERVICE);
> > mSensMan.registerListener(this,
> >
> > mSensMan.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD), //
> > Anonymous Sensors- no further use for them.
> > SensorManager.SENSOR_DELAY_UI);
> > mSensMan.registerListener(this,
> > mSensMan.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
> > SensorManager.SENSOR_DELAY_UI);
> > }
>
> > @Override
> > public void onAccuracyChanged(Sensor sensor, int accuracy) {
> > // Do nothing
> > }
>
> > @Override
> > public void onSensorChanged(SensorEvent event) {
> > switch (event.sensor.getType()) {
> > case Sensor.TYPE_ACCELEROMETER:
> > /*
> > * NOTE: The data must be copied off the
> > event.values
> > * as the system is reusing that array in all
> > SensorEvents.
> > * Simply assigning:
> > * mGravs = event.values won't work.
> > *
> > * I use a member array in an attempt to reduce
> > garbage production.
> > */
> > System.arraycopy(event.values, 0, mGravs, 0, 3);
> > break;
> > case Sensor.TYPE_MAGNETIC_FIELD:
> > // Here let's try another way:
> > for (int i=0;i<3;i++) mGeoMags[i] = event.values[i];
> > break;
> > default:
> > return;
> > }
>
> > if (SensorManager.getRotationMatrix(mRotationM, null,
> > mGravs,
> > mGeoMags)){
> > // Rotate to the camera's line of view (Y axis along
> > the camera's
> > axis)
> > // TODO: Find how to use android.opengl.Matrix to
> > rotate to an
> > arbitrary coordinate system.
> > SensorManager.remapCoordinateSystem(mRotationM,
> > SensorManager.AXIS_X,
> > SensorManager.AXIS_Z,
>
> ...
>
> read more »
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