Android获取四元数数据

Question

快速简单。如何从传感器获取四元数数据？基本上我需要：

float quaternion_x = ?
float quaternion_y = ?
float quaternion_z = ?
float quaternion_w = ?

我有这样的东西：

if (event.sensor.getType() == Sensor.TYPE_ROTATION_VECTOR)
{
    float[] values = event.values;

    float quaternion_x = values[0];
    float quaternion_y = values[1];
    float quaternion_z = values[2];
    float quaternion_w = values[3];  <----- ERROR HERE 
}

我得到一个索引超出范围的异常，因为 values 里面只有 3 个值。根据此页面： http://developer.android.com/guide/topics/sensors/sensors_motion.html 应该有 4 个值还是我理解有误？

Answer 1

SensorManager class 提供了一个帮助函数来为您转换：

SensorManager.getQuaternionFromVector(Q, values);
float[] quaternion_w = Q[0];
float[] quaternion_x = Q[1];
float[] quaternion_y = Q[2];
float[] quaternion_z = Q[3];

Answer 2

android 执行 getOrientation returns 与 getQuaterionFromVector[ 相同的值=19=]。因此，如果需要，您可以采用这些值并构造四元数；

float[] quaternion = new float[4]; quaternion[0] = 0; //w quaternion[1] = orientation[0]; //x quaternion[2] = orientation[1]; //y quaternion[3] = orientation[2]; //z

我用这个代码查了一下。

@Override public void onSensorChanged(SensorEvent event) { if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD) mMagneticField = event.values; if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) mGravity = event.values; if ((mGravity == null) || (mMagneticField == null)) return; float R[] = new float[9]; float I[] = new float[9]; boolean success = SensorManager.getRotationMatrix(R, I, mGravity, mMagneticField); if (success) { mOrientation = new float[3]; mQuaternion = new float[4]; SensorManager.getOrientation(R, mOrientation); mAzimut = mOrientation[0]; // orientation contains: azimut, pitch and roll mPitch = mOrientation[1]; mRoll = mOrientation[2]; SensorManager.getQuaternionFromVector(mQuaternion, mOrientation); if(mAzimut - mQuaternion[1] == 0 && mPitch - mQuaternion[2] == 0 && mRoll - mQuaternion[3] == 0){ Log.d("ORIENTATION", "QUATERNION IS THE SAME"); } notifyObservers(); } }

Android获取四元数数据

Android get quaternion data

android

quaternions

android-sensors