Targeting Android AR

Question

I am creating a program for displaying objects from a map to a camera, and this works almost perfectly, except for a few degrees to the left and right of the vertical orientation (for example, at 80-110 and 260-280 degrees). In other + -320 degrees, it works well. I tried using TYPE_ROTATION_VECTOR and an accelerometer with a magnetometer, and they have the same result. Does anyone know a solution?

from TYPE_ROTATION_VECTOR:

if (event.sensor.getType() == Sensor.TYPE_ROTATION_VECTOR) { float[] roationV = new float[16]; SensorManager.getRotationMatrixFromVector(roationV, event.values); float[] orientationValuesV = new float[3]; SensorManager.getOrientation(roationV, orientationValuesV); tvHeading.setText(String.format( "Coordinates: lat = %1$.2f, lon = %2$.2f, time = %3$.2f", orientationValuesV[0], orientationValuesV[1], orientationValuesV[2])); float[] rotationMatrix=new float[16]; mSensorManager.getRotationMatrixFromVector(rotationMatrix, event.values); float[] orientationValues = new float[3]; SensorManager.getOrientation(rotationMatrix, orientationValues); double azimuth = Math.toDegrees(orientationValues[0]); double pitch = Math.toDegrees(orientationValues[1]); double roll = Math.toDegrees(orientationValues[2]); tvOrientation.setText(String.format( "Coordinates: lat = %1$.2f, lon = %2$.2f, time = %3$.2f", azimuth,pitch,roll)); } 

with accelerometer + magnetometer

 if (event.sensor == mAccelerometer) { System.arraycopy(event.values, 0, mLastAccelerometer, 0, event.values.length); mLastAccelerometer = meanFilterAccelSmoothing .addSamples(mLastAccelerometer); mLastAccelerometer = medianFilterAccelSmoothing .addSamples(mLastAccelerometer); for (int i = 0; i < mLastAccelerometer.length; i++) { mLastAccelerometer[i] = (float) Math.floor(mLastAccelerometer[i] * 1000) / 1000; } mLastAccelerometerSet = true; } if (event.sensor == mMagnetometer) { System.arraycopy(event.values, 0, mLastMagnetometer, 0, event.values.length); mLastMagnetometer = meanFilterMagneticSmoothing.addSamples(mLastMagnetometer); mLastMagnetometer = medianFilterMagneticSmoothing.addSamples(mLastMagnetometer); for (int i = 0; i < mLastMagnetometer.length; i++) { mLastMagnetometer[i] = (float) Math.floor(mLastMagnetometer[i] * 1000) / 1000; } mLastMagnetometerSet = true; } if (mLastAccelerometerSet && mLastMagnetometerSet) { SensorManager.getRotationMatrix(mR, null, mLastAccelerometer, mLastMagnetometer); SensorManager.getOrientation(mR, mOrientation); if (angeles.size() > 0) { for (int i = 0; i < mapObjects.size(); i++) { compassFunc(i, mOrientation[0], mOrientation[1], mOrientation[2]); } } private void compassFunc(int number, float... values) { double angularXSpeed = Math.floor(values[0] * 180 / Math.PI * 100) / 100; double angularYSpeed = Math.floor(values[1] * 180 / Math.PI * 100) / 100; double angularZSpeed = Math.floor(values[2] * 180 / Math.PI * 100) / 100; tvOrientation.setText(String.format( "Screen: lt= %1$.2f : %2$.2f,rt= %3$.2f : %4$.2f,lb= %5$.2f : %6$.2f,rb= %7$.2f : %8$.2f", xLeftTop, yLeftTop, xRightTop,yRightTop,xLeftBottom,yLeftBottom,xRightBottom,yRightBottom)); } 

Answer 1

This sounds like a typical Gimbal Lock case. Your description of how rotation around one axis acts when the other reaches + -90 degrees indicates that this is indeed so.

This is a fundamental problem with Euler angles (Yaw / Azimuth, Pitch, Roll), so most of these calculations are performed using a rotation matrix or quaternions, and Euler angles are most often used only when a specific orientation should be displayed to a person (people are usually poorly versed in matrices rotation and quaternions).

The ROTATION_VECTOR sensor outputs data in the quaternion format ( source ), although with the changed values ​​and the getRotationMatrixFromVector() method it turns it into a rotation matrix. I would suggest using one of these descriptions for your internal calculations.

The answers to this similar question contain some specific suggestions on how to solve the problem.