使用 getRotationMatrix() 和 getOrientation() 查找方向 [英] finding orientation using getRotationMatrix() and getOrientation()

问题描述

我试图获得指向相机外的矢量方向，相对于磁北.我的印象是我需要使用从 getOrientation() 返回的值，但我不确定它们代表什么.当我改变手机的方向(旋转 90 度不会改变 90 度的值)时，我从 getOrientation() 获得的值不会发生可预测的变化.我需要知道 getOrientation() 返回的值是什么意思.到目前为止，我所写的内容如下:

Im trying to get the direction of the vector pointing out of the camera, with respect to magnetic north. I'm under the impression that I need to use the values returned from getOrientation(), but I'm not sure what they represent. The values I get from getOrientation() don't change predictably when I change the orientation of the phone (rotating 90 degrees does not change values by 90 degrees). I need to know what the values returned by getOrientation() mean. What I have so far is written below:

package com.example.orientation;

import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.Toast;

public class Orientation extends Activity{

 private SensorManager mSM;
 private mSensorEventListener mSEL;

    float[] inR = new float[16];
    float[] outR= new float[16];
    float[] I = new float[16];
    float[] gravity = new float[3];
    float[] geomag = new float[3];
    float[] orientVals = new float[3];

    final float pi = (float) Math.PI;
    final float rad2deg = 180/pi;    

 /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mSM = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
        mSEL = new mSensorEventListener();  

        mSM.registerListener(mSEL, 
       mSM.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
       SensorManager.SENSOR_DELAY_NORMAL);

     mSM.registerListener(mSEL, 
       mSM.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD), 
       SensorManager.SENSOR_DELAY_NORMAL);

 }



 private class mSensorEventListener implements SensorEventListener{

  @Override
  public void onAccuracyChanged(Sensor arg0, int arg1) {}

  @Override
  public void onSensorChanged(SensorEvent event) {

   // If the sensor data is unreliable return
   if (event.accuracy == SensorManager.SENSOR_STATUS_UNRELIABLE)
    return;

   // Gets the value of the sensor that has been changed
   switch (event.sensor.getType()){  
   case Sensor.TYPE_ACCELEROMETER:
    gravity = event.values.clone();
    break;
   case Sensor.TYPE_MAGNETIC_FIELD:
    geomag = event.values.clone();
    break;
   }

   // If gravity and geomag have values then find rotation matrix
   if (gravity != null && geomag != null){

    // checks that the rotation matrix is found
    boolean success = SensorManager.getRotationMatrix(inR, I, gravity, geomag);
    if (success){

     // Re-map coordinates so y-axis comes out of camera
     SensorManager.remapCoordinateSystem(inR, SensorManager.AXIS_X, 
       SensorManager.AXIS_Z, outR);

     // Finds the Azimuth and Pitch angles of the y-axis with 
     // magnetic north and the horizon respectively
     SensorManager.getOrientation(outR, orientVals);
     float azimuth = orientVals[0]*rad2deg;
     float pitch = orientVals[1]*rad2deg;
     float roll = orientVals[2]*rad2deg;

     // Displays a pop up message with the azimuth and inclination angles
     String endl = System.getProperty("line.separator");
     Toast.makeText(getBaseContext(), 
       "Rotation:" +
       outR[0] + " " + outR[1] + " " + outR[2] + endl +
       outR[4] + " " + outR[5] + " " + outR[6] + endl +
       outR[8] + " " + outR[9] + " " + outR[10] + endl +endl +
       "Azimuth: " + azimuth + " degrees" + endl + 
       "Pitch: " + pitch + " degrees" + endl +
       "Roll: " + roll + " degrees", 
       Toast.LENGTH_LONG).show();
    } /*else
     Toast.makeText(getBaseContext(), 
       "Get Rotation Matrix Failed", Toast.LENGTH_LONG).show();*/
   }   
  }

    }

}

我查看了关于 sensorManager 类的文档，但它没有帮助解决这个问题.如果有人能帮助我从中获得意义，我将不胜感激.我正在运行 Android 2.1 的 Nexus One 上进行测试

I've looked at the documentation on the sensorManager class, but it hasn't helped solve this. If anyone could help me get meaning out of the this I would really appreciate it. I'm testing on a Nexus One running Android 2.1

推荐答案

因为我是 android 新手，所以我使用 toast 在屏幕上显示信息.我将其更改为仅更新视图上的文本，这似乎解决了它.我还发现我认为 orientVals 实际上是正确的.对于我需要的东西，不使用卷.也没有意识到有一种内置的从 rad 转换为 deg 的方法，所以我只是使用了它.

Because I was new to android I was using toast to display the information on the screen. I changed it to just update text on a view and that seemed to fix it. I also figured out that what I assumed the orientVals actually were is correct. For what I need the roll is not used. Also didnt realize there was a way to convert from rad to deg built in so I just used that.

这篇关于使用 getRotationMatrix() 和 getOrientation() 查找方向的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！