我正在创建3D Compass应用程序.
我正在使用getOrientation方法来获取方向(几乎相同的实现,如here).如果我把手机放在桌子上,它的效果很好,但是当手机顶部指向天空(图片上的Z轴为零时,球体为地球),getOrientation开始给出非常糟糕的结果.它给出Z轴在0到180度之间的几个实数值的值.有什么办法抑制这种行为吗？我创建了一个little video描述问题(对质量不好的抱歉).提前致谢.
解：
当你旋转模型时,有区别：
gl.glRotatef(_angleY,0f,1f,0f); //ROLL gl.glRotatef(_angleX,0f); //ELEVATION gl.glRotatef(_angleZ,1f); //AZIMUTH gl.glRotatef(_angleX,0f); //ELEVATION gl.glRotatef(_angleY,0f); //ROLL gl.glRotatef(_angleZ,1f); //AZIMUTH
解决方法
嗯,我可以看到至少有一个问题,你的这种方法.
我假设您将与您的磁力计相对应的3D矢量与平均低通滤波器相结合,以平滑数据.虽然这种方法对于传感器值无差异,如来自加速度计的原始数据,但是从磁力计中获取的角度变量不会如此重要.为什么有人会问？
因为这些角度变量(方位角,俯仰角,滚动角)具有上限和下限,这意味着高于180度(如181度)的任何值都将绕到181-360 = -179度,任何变量低于-180度会在另一个方向缠绕.所以当这些角度变量之一接近这些阈值(180或-180)时,这个变量将倾向于摆动到接近于这2个极值的值.当您盲目地将低通滤波器应用于这些值时,您可以从180度向-180度平滑下降,或者从-180到180度平滑地增加.无论哪种方式,结果将看起来像您的视频上面…只要一个直接对getOrientation(…)的原始角度数据应用平均缓冲区,这个问题将会出现(应该不仅仅存在于电话是直立的情况,而且在方位角环绕的情况下也可能也可以测试这些错误…).
你说你用一个缓冲区大小为1测试了这个.理论上说,如果没有平均值,这个问题不应该出现,尽管在过去看到的循环缓冲区的某些实现中,可能意味着仍然平均至少有一个过去的价值,而不是没有平均.如果是这种情况,我们发现你的错误的根本原因.
不幸的是,在使用标准平均滤波器的同时,还没有很多优雅的解决方案可以实现.在这种情况下,我通常会做的是切换到另一种类型的低通滤波器,它不需要任何深度的缓冲区来操作：简单的IIR滤波器(1)：
diff = x [n] -y [n-1]
y [n] – y [n-1] = alpha *(x [n] -y [n-1])= alpha * diff
…其中y是滤波角,x是原始角,并且α<1类似于时间常数,因为α= 1对应于无滤波器情况,并且低通滤波器的频率截止获得阿尔法接近零时降低.目前,急性眼睛可能已经注意到这对应于简单的比例控制器. 这样的滤波器允许补偿角度值的包围,因为我们可以将差值360加上或减去diff,以确保abs(diff)≤180,这又确保滤波角度值总是增加/减小在最佳方向达到“设定值”. 计算周期性地调度给定原始角度值x的滤波角度值y的示例函数调用可以是这样的：
private float restrictAngle(float tmpAngle){
while(tmpAngle>=180) tmpAngle-=360;
while(tmpAngle<-180) tmpAngle+=360;
return tmpAngle;
}
//x is a raw angle value from getOrientation(...)
//y is the current filtered angle value
private float calculateFilteredAngle(float x,float y){
final float alpha = 0.1f;
float diff = x-y;
//here,we ensure that abs(diff)<=180
diff = restrictAngle(diff);
y += alpha*diff;
//ensure that y stays within [-180,180[ bounds
y = restrictAngle(y);
return y;
}
函数calculateFilteredAngle(float x,float y)可以使用这样的方式定期调用(来自getOrientation(…)函数的方位角的示例)
filteredAzimuth = calculateFilteredAngle(azimuth,filteredAzimuth);
使用这种方法,滤波器不会像OP所提到的平均滤波器那样行不通.
由于我无法加载OP上传的.apk,所以我决定实施自己的测试项目,以查看修正是否正常工作.这是整个代码(它不使用.XML作为主要的布局,所以我没有包括它).只需将其复制到测试项目中,看看它是否适用于特定的设备(在HTC Desire w / Android v.2.1上测试功能)：
文件1：Compass3DActivity.java：
package com.epichorns.compass3D;
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.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
public class Compass3DActivity extends Activity {
//Textviews for showing angle data
TextView mTextView_azimuth;
TextView mTextView_pitch;
TextView mTextView_roll;
TextView mTextView_filtered_azimuth;
TextView mTextView_filtered_pitch;
TextView mTextView_filtered_roll;
float mAngle0_azimuth=0;
float mAngle1_pitch=0;
float mAngle2_roll=0;
float mAngle0_filtered_azimuth=0;
float mAngle1_filtered_pitch=0;
float mAngle2_filtered_roll=0;
private Compass3DView mCompassView;
private SensorManager sensorManager;
//sensor calculation values
float[] mGravity = null;
float[] mGeomagnetic = null;
float Rmat[] = new float[9];
float Imat[] = new float[9];
float orientation[] = new float[3];
SensorEventListener mAccelerometerListener = new SensorEventListener(){
public void onAccuracyChanged(Sensor sensor,int accuracy) {}
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER){
mGravity = event.values.clone();
processSensorData();
}
}
};
SensorEventListener mMagnetometerListener = new SensorEventListener(){
public void onAccuracyChanged(Sensor sensor,int accuracy) {}
public void onSensorChanged(SensorEvent event) {
if (event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD){
mGeomagnetic = event.values.clone();
processSensorData();
update();
}
}
};
private float restrictAngle(float tmpAngle){
while(tmpAngle>=180) tmpAngle-=360;
while(tmpAngle<-180) tmpAngle+=360;
return tmpAngle;
}
//x is a raw angle value from getOrientation(...)
//y is the current filtered angle value
private float calculateFilteredAngle(float x,float y){
final float alpha = 0.3f;
float diff = x-y;
//here,we ensure that abs(diff)<=180
diff = restrictAngle(diff);
y += alpha*diff;
//ensure that y stays within [-180,180[ bounds
y = restrictAngle(y);
return y;
}
public void processSensorData(){
if (mGravity != null && mGeomagnetic != null) {
boolean success = SensorManager.getRotationMatrix(Rmat,Imat,mGravity,mGeomagnetic);
if (success) {
SensorManager.getOrientation(Rmat,orientation);
mAngle0_azimuth = (float)Math.toDegrees((double)orientation[0]); // orientation contains: azimut,pitch and roll
mAngle1_pitch = (float)Math.toDegrees((double)orientation[1]); //pitch
mAngle2_roll = -(float)Math.toDegrees((double)orientation[2]); //roll
mAngle0_filtered_azimuth = calculateFilteredAngle(mAngle0_azimuth,mAngle0_filtered_azimuth);
mAngle1_filtered_pitch = calculateFilteredAngle(mAngle1_pitch,mAngle1_filtered_pitch);
mAngle2_filtered_roll = calculateFilteredAngle(mAngle2_roll,mAngle2_filtered_roll);
}
mGravity=null; //oblige full new refresh
mGeomagnetic=null; //oblige full new refresh
}
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout ll = new LinearLayout(this);
LinearLayout.LayoutParams llParams = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT,LinearLayout.LayoutParams.FILL_PARENT);
ll.setLayoutParams(llParams);
ll.setOrientation(LinearLayout.VERTICAL);
ViewGroup.LayoutParams txtParams = new ViewGroup.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT);
mTextView_azimuth = new TextView(this);
mTextView_azimuth.setLayoutParams(txtParams);
mTextView_pitch = new TextView(this);
mTextView_pitch.setLayoutParams(txtParams);
mTextView_roll = new TextView(this);
mTextView_roll.setLayoutParams(txtParams);
mTextView_filtered_azimuth = new TextView(this);
mTextView_filtered_azimuth.setLayoutParams(txtParams);
mTextView_filtered_pitch = new TextView(this);
mTextView_filtered_pitch.setLayoutParams(txtParams);
mTextView_filtered_roll = new TextView(this);
mTextView_filtered_roll.setLayoutParams(txtParams);
mCompassView = new Compass3DView(this);
ViewGroup.LayoutParams compassParams = new ViewGroup.LayoutParams(200,200);
mCompassView.setLayoutParams(compassParams);
ll.addView(mCompassView);
ll.addView(mTextView_azimuth);
ll.addView(mTextView_pitch);
ll.addView(mTextView_roll);
ll.addView(mTextView_filtered_azimuth);
ll.addView(mTextView_filtered_pitch);
ll.addView(mTextView_filtered_roll);
setContentView(ll);
sensorManager = (SensorManager) this.getSystemService(Context.SENSOR_SERVICE);
sensorManager.registerListener(mAccelerometerListener,sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),SensorManager.SENSOR_DELAY_UI);
sensorManager.registerListener(mMagnetometerListener,sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),SensorManager.SENSOR_DELAY_UI);
update();
}
@Override
public void onDestroy(){
super.onDestroy();
sensorManager.unregisterListener(mAccelerometerListener);
sensorManager.unregisterListener(mMagnetometerListener);
}
private void update(){
mCompassView.changeAngles(mAngle1_filtered_pitch,mAngle2_filtered_roll,mAngle0_filtered_azimuth);
mTextView_azimuth.setText("Azimuth: "+String.valueOf(mAngle0_azimuth));
mTextView_pitch.setText("Pitch: "+String.valueOf(mAngle1_pitch));
mTextView_roll.setText("Roll: "+String.valueOf(mAngle2_roll));
mTextView_filtered_azimuth.setText("Azimuth: "+String.valueOf(mAngle0_filtered_azimuth));
mTextView_filtered_pitch.setText("Pitch: "+String.valueOf(mAngle1_filtered_pitch));
mTextView_filtered_roll.setText("Roll: "+String.valueOf(mAngle2_filtered_roll));
}
}
文件2：Compass3DView.java：
package com.epichorns.compass3D;
import android.content.Context;
import android.opengl.GLSurfaceView;
public class Compass3DView extends GLSurfaceView {
private Compass3DRenderer mRenderer;
public Compass3DView(Context context) {
super(context);
mRenderer = new Compass3DRenderer(context);
setRenderer(mRenderer);
}
public void changeAngles(float angle0,float angle1,float angle2){
mRenderer.setAngleX(angle0);
mRenderer.setAngleY(angle1);
mRenderer.setAngleZ(angle2);
}
}
文件3：Compass3DRenderer.java：
package com.epichorns.compass3D;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.FloatBuffer;
import java.nio.ShortBuffer;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;
import android.content.Context;
import android.opengl.GLSurfaceView;
public class Compass3DRenderer implements GLSurfaceView.Renderer {
Context mContext;
// a raw buffer to hold indices
ShortBuffer _indexBuffer;
// raw buffers to hold the vertices
FloatBuffer _vertexBuffer0;
FloatBuffer _vertexBuffer1;
FloatBuffer _vertexBuffer2;
FloatBuffer _vertexBuffer3;
FloatBuffer _vertexBuffer4;
FloatBuffer _vertexBuffer5;
int _numVertices = 3; //standard triangle vertices = 3
FloatBuffer _textureBuffer0123;
//private FloatBuffer _light0Position;
//private FloatBuffer _light0Ambient;
float _light0Position[] = new float[]{10.0f,10.0f,0.0f};
float _light0Ambient[] = new float[]{0.05f,0.05f,1.0f};
float _light0Diffuse[] = new float[]{0.5f,0.5f,1.0f};
float _light0Specular[] = new float[]{0.7f,0.7f,1.0f};
float _matAmbient[] = new float[] { 0.6f,0.6f,1.0f };
float _matDiffuse[] = new float[] { 0.6f,1.0f };
private float _angleX=0f;
private float _angleY=0f;
private float _angleZ=0f;
Compass3DRenderer(Context context){
super();
mContext = context;
}
public void setAngleX(float angle) {
_angleX = angle;
}
public void setAngleY(float angle) {
_angleY = angle;
}
public void setAngleZ(float angle) {
_angleZ = angle;
}
FloatBuffer InitFloatBuffer(float[] src){
ByteBuffer bb = ByteBuffer.allocateDirect(4*src.length);
bb.order(ByteOrder.nativeOrder());
FloatBuffer inBuf = bb.asFloatBuffer();
inBuf.put(src);
return inBuf;
}
ShortBuffer InitShortBuffer(short[] src){
ByteBuffer bb = ByteBuffer.allocateDirect(2*src.length);
bb.order(ByteOrder.nativeOrder());
ShortBuffer inBuf = bb.asShortBuffer();
inBuf.put(src);
return inBuf;
}
//Init data for our rendered pyramid
private void initTriangles() {
//Side faces triangles
float[] coords = {
-0.25f,-0.5f,0.25f,0f
};
float[] coords1 = {
0.25f,-0.25f,0f
};
float[] coords2 = {
0.25f,0f
};
float[] coords3 = {
-0.25f,0f
};
//Base triangles
float[] coords4 = {
-0.25f,0.25f
};
float[] coords5 = {
-0.25f,-0.25f
};
float[] textures0123 = {
// Mapping coordinates for the vertices (UV mapping CW)
0.0f,0.0f,// bottom left
1.0f,// bottom right
0.5f,1.0f,// top ctr
};
_vertexBuffer0 = InitFloatBuffer(coords);
_vertexBuffer0.position(0);
_vertexBuffer1 = InitFloatBuffer(coords1);
_vertexBuffer1.position(0);
_vertexBuffer2 = InitFloatBuffer(coords2);
_vertexBuffer2.position(0);
_vertexBuffer3 = InitFloatBuffer(coords3);
_vertexBuffer3.position(0);
_vertexBuffer4 = InitFloatBuffer(coords4);
_vertexBuffer4.position(0);
_vertexBuffer5 = InitFloatBuffer(coords5);
_vertexBuffer5.position(0);
_textureBuffer0123 = InitFloatBuffer(textures0123);
_textureBuffer0123.position(0);
short[] indices = {0,1,2};
_indexBuffer = InitShortBuffer(indices);
_indexBuffer.position(0);
}
public void onSurfaceCreated(GL10 gl,EGLConfig config) {
gl.glEnable(GL10.GL_CULL_FACE); // enable the differentiation of which side may be visible
gl.glShadeModel(GL10.GL_SMOOTH);
gl.glFrontFace(GL10.GL_CCW); // which is the front? the one which is drawn counter clockwise
gl.glCullFace(GL10.GL_BACK); // which one should NOT be drawn
initTriangles();
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
}
public void onDrawFrame(GL10 gl) {
gl.glPushMatrix();
gl.glClearColor(0,1.0f); //clipping backdrop color
// clear the color buffer to show the ClearColor we called above...
gl.glClear(GL10.GL_COLOR_BUFFER_BIT);
// set rotation
gl.glRotatef(_angleY,0f); //ROLL
gl.glRotatef(_angleX,0f); //ELEVATION
gl.glRotatef(_angleZ,1f); //AZIMUTH
//Draw our pyramid
//4 side faces
gl.glColor4f(0.5f,0.5f);
gl.glVertexPointer(3,GL10.GL_FLOAT,_vertexBuffer0);
gl.glDrawElements(GL10.GL_TRIANGLES,_numVertices,GL10.GL_UNSIGNED_SHORT,_indexBuffer);
gl.glColor4f(0.5f,_vertexBuffer1);
gl.glDrawElements(GL10.GL_TRIANGLES,_indexBuffer);
gl.glColor4f(0f,_vertexBuffer2);
gl.glDrawElements(GL10.GL_TRIANGLES,_vertexBuffer3);
gl.glDrawElements(GL10.GL_TRIANGLES,_indexBuffer);
//Base face
gl.glColor4f(0f,_vertexBuffer4);
gl.glDrawElements(GL10.GL_TRIANGLES,_indexBuffer);
gl.glVertexPointer(3,_vertexBuffer5);
gl.glDrawElements(GL10.GL_TRIANGLES,_indexBuffer);
gl.glPopMatrix();
}
public void onSurfaceChanged(GL10 gl,int w,int h) {
gl.glViewport(0,w,h);
gl.glViewport(0,h);
}
}
