8

请忍受我的长问题，我试图尽可能清楚。

我想要做的是，在使用相机拍摄照片时获取姿态（滚动俯仰和偏航），然后将姿态值保存到 nsuserdefaults。保存后，改变方向，然后通过不断比较姿态值（保存的和当前的），尝试使手机保持与拍照时相同的姿态。

出于界面的目的，用户界面在屏幕上有 3 个点（每个姿态参数一个），用于指导拍摄照片的正确方向。达到正确的姿态后，屏幕上会显示比赛标志。

我一直在寻找滚动，俯仰和偏航值：

CMQuaternion quat = self.motionManager.deviceMotion.attitude.quaternion;
myRoll = radiansToDegrees(atan2(2*(quat.y*quat.w - quat.x*quat.z), 1 - 2*quat.y*quat.y - 2*quat.z*quat.z)) ;
myPitch = radiansToDegrees(atan2(2*(quat.x*quat.w + quat.y*quat.z), 1 - 2*quat.x*quat.x - 2*quat.z*quat.z));
myYaw = radiansToDegrees(2*(quat.x*quat.y + quat.w*quat.z));

当我注意到偏航值存在一些差异时，我搜索并可以从这里找到：link，那个

yaw, pitch and roll 从一个四元数你会遇到和你只使用 yaw, pitch 和 roll 一样的问题。你必须在代码中到处使用四元数，忘记偏航、俯仰和滚动

所以现在我想我必须重新编写所有代码......请你能指出我为此目的使用四元数的示例代码吗？

这是我正在处理的代码：

在 ViewController.m 中，图像内：didFinishSavingWithError：

[self.motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue mainQueue] withHandler:^(CMDeviceMotion *motion, NSError *error) {

        CMQuaternion quat = self.motionManager.deviceMotion.attitude.quaternion;
        double tempYaw = radiansToDegrees(asin(2*(quat.x*quat.y + quat.w*quat.z)));
        double tempRoll = radiansToDegrees(atan2(2*(quat.y*quat.w - quat.x*quat.z), 1 - 2*quat.y*quat.y - 2*quat.z*quat.z)) ;
        double tempPitch = radiansToDegrees(atan2(2*(quat.x*quat.w + quat.y*quat.z), 1 - 2*quat.x*quat.x - 2*quat.z*quat.z));

        if (savingGyroOrientation == YES) {

            NSLog(@"Roll = %f degrees",tempRoll);
            NSLog(@"Pitch = %f degrees",tempPitch);
            NSLog(@"Yaw = %f degrees",tempYaw);

            [self.deviceStatus setDouble:tempRoll forKey:@"DeviceRoll"];
            [self.deviceStatus setDouble:tempPitch forKey:@"DevicePitch"];
            [self.deviceStatus setDouble:tempYaw forKey:@"DeviceYaw"];
            [self.deviceStatus synchronize];

            savingGyroOrientation = NO;
            checkingGyroOrientation = YES;
            self.savingLabel.hidden = YES;
            self.startTimerButton.hidden = NO;

        }
        savingGyroOrientation = NO;
        checkingGyroOrientation = YES;
        self.savingLabel.hidden = YES;
        self.startTimerButton.hidden = NO;
    }

     if (timerRunning == YES) {
         if (checkingGyroOrientation == YES) {

             self.takePicButton.hidden = YES;

             int xRoll, yPitch, xYaw, yYaw;
             // Roll Checking
             if (tempRoll >= [self.deviceStatus doubleForKey:@"DeviceRoll"]-1 && tempRoll <= [self.deviceStatus doubleForKey:@"DeviceRoll"]+1 ) {

                 [self.rollDot setFrame:CGRectMake(150, 195, 20, 20)];
                 self.rollToR.hidden = YES;
                 self.rollToL.hidden = YES;
                 self.rollDot.hidden = NO;
                 rollOk = YES;
             }else{
                 rollOk = NO;
                 self.rollDot.hidden = YES;
                 self.rollToR.hidden = NO;
                 self.rollToL.hidden = NO;

                 if (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"] < 0) {
                     xRoll = 150 + (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"]);
                     self.rollToR.hidden = YES;
                     if (xRoll <= 0) {
                         [self.rollToL setFrame:CGRectMake(0, 195, 20, 20)];
                     }else if (xRoll>= 300){
                         [self.rollToL setFrame:CGRectMake(300, 195, 20, 20)];
                     }else{
                         [self.rollToL setFrame:CGRectMake(xRoll, 195, 20, 20)];
                     }
                 }
                 if (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"] > 0){
                     xRoll = 150 + (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"]);
                     self.rollToL.hidden = YES;
                     if (xRoll <= 0) {
                         [self.rollToR setFrame:CGRectMake(0, 195, 20, 20)];
                     }else if (xRoll>=300){
                         [self.rollToR setFrame:CGRectMake(300, 195, 20, 20)];
                     }else{
                         [self.rollToR setFrame:CGRectMake(xRoll, 195, 20, 20)];
                     }
                 }
                 if (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"] > 180){
                     xRoll = 150 + (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"]-360);
                     self.rollToR.hidden = YES;
                     if (xRoll <= 0) {
                         [self.rollToL setFrame:CGRectMake(0, 195, 20, 20)];
                     }else if (xRoll>=300){
                         [self.rollToL setFrame:CGRectMake(300, 195, 20, 20)];
                     }else{
                         [self.rollToL setFrame:CGRectMake(xRoll, 195, 20, 20)];
                     }
                 }
                 if (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"] < -180){
                     xRoll = 150 + (tempRoll - [self.deviceStatus doubleForKey:@"DeviceRoll"]+360);
                     self.rollToL.hidden = YES;
                     if (xRoll <= 0) {
                         [self.rollToR setFrame:CGRectMake(0, 195, 20, 20)];
                     }else if (xRoll >= 300){
                         [self.rollToR setFrame:CGRectMake(300, 195, 20, 20)];
                     }else{
                         [self.rollToR setFrame:CGRectMake(xRoll, 195, 20, 20)];
                     }
                 }
             }
             //Pitch Checking
             if (tempPitch >= [self.deviceStatus doubleForKey:@"DevicePitch"]-1 && tempPitch <= [self.deviceStatus doubleForKey:@"DevicePitch"]+1) {
                 [self.pitchDot setFrame:CGRectMake(150, 195, 20, 20)];
                 self.pitchDot.hidden = NO;
                 self.pitchToDown.hidden = YES;
                 self.pitchToUp.hidden = YES;
                 pitchOk = YES;
             }else{
                 pitchOk = NO;
                 self.pitchDot.hidden = YES;
                 self.pitchToDown.hidden = NO;
                 self.pitchToUp.hidden = NO;
                 if (tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"] < 0) {
                     yPitch = 195+(tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"]);
                     //                         NSLog(@"tempPitch is %0.02f Difference is %0.02f, yPitch is %0.02f",tempPitch, tempPitch-[self.deviceStatus doubleForKey:@"DevicePitch"],195+(tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"]));
                     self.pitchToDown.hidden = YES;
                     if (yPitch <= 0) {
                         [self.pitchToUp setFrame:CGRectMake(150, 0, 20, 20)];
                     }else if (yPitch >= 390) {
                         [self.pitchToUp setFrame:CGRectMake(150, 390, 20, 20)];
                     }else{
                         [self.pitchToUp setFrame:CGRectMake(150, yPitch, 20, 20)];
                     }
                 }
                 if (tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"] > 0){
                     yPitch = 195+(tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"]);
                     //                         NSLog(@"tempPitch is %0.02f Difference is %0.02f, yPitch is %0.02f",tempPitch, tempPitch-[self.deviceStatus doubleForKey:@"DevicePitch"],195+(tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"]));
                     self.pitchToUp.hidden = YES;
                     if (yPitch <= 0) {
                         [self.pitchToDown setFrame:CGRectMake(150, 0, 20, 20)];
                     }else if (yPitch >= 390) {
                         [self.pitchToDown setFrame:CGRectMake(150, 390, 20, 20)];
                     }else{
                         [self.pitchToDown setFrame:CGRectMake(150, yPitch, 20, 20)];
                     }
                 }
                 if (tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"] < -180){
                     yPitch = 195+tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"] + 360;
                     //                         NSLog(@"tempPitch is %0.02f Difference is %0.02f, yPitch is %0.02f",tempPitch, tempPitch-[self.deviceStatus doubleForKey:@"DevicePitch"],195+(tempPitch - [self.deviceStatus doubleForKey:@"DevicePitch"]));
                     //                         NSLog(@"*yPitch is %d",yPitch);
                     self.pitchToUp.hidden = YES;
                     self.pitchToDown.hidden = NO;
                     if (yPitch <= 0 ) {
                         [self.pitchToDown setFrame:CGRectMake(150, 0, 20, 20)];
                     }else if (yPitch >= 390) {
                         [self.pitchToDown setFrame:CGRectMake(150, 390, 20, 20)];
                     }else{
                         [self.pitchToDown setFrame:CGRectMake(150, yPitch, 20, 20)];
                     }
                 }
             }
             if (tempYaw >= [self.deviceStatus doubleForKey:@"DeviceYaw"]-2 && tempYaw <= [self.deviceStatus doubleForKey:@"DeviceYaw"]+2) {

                 [self.yawDot setFrame:CGRectMake(150, 195, 20, 20)];
                 self.yawDot.hidden = NO;
                 self.rotateRight.hidden = YES;
                 self.rotateLeft.hidden = YES;
                 yawOk = YES;
             }else{
                 yawOk = NO;
                 self.yawDot.hidden = YES;
                 self.rotateRight.hidden = NO;
                 self.rotateLeft.hidden = NO;

                 if (tempYaw - [self.deviceStatus doubleForKey:@"DeviceYaw"] < 0 ) {
                     xYaw = 150+(tempYaw - [self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     yYaw = 195-1.3*(tempYaw - [self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     NSLog(@"current yaw is %0.02f Difference is %0.02f",tempYaw, tempYaw-[self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     NSLog(@"saved Yaw is %0.02f",[self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     NSLog(@"xYaw is %d, yYaw is %d",xYaw,yYaw);
                     self.rotateRight.hidden = YES;
                     if (xYaw <=0 && yYaw >=390) {
                         [self.rotateLeft setFrame:CGRectMake(0, 390, 20, 20)];
                     }else{
                         [self.rotateLeft setFrame:CGRectMake(xYaw, yYaw, 20, 20)];
                     }

                 }if (tempYaw - [self.deviceStatus doubleForKey:@"DeviceYaw"] > 0){
                     xYaw = 150+(tempYaw - [self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     yYaw = 195-1.3*(tempYaw - [self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     NSLog(@"current yaw is %0.02f Difference is %0.02f",tempYaw, tempYaw-[self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     NSLog(@"saved Yaw is %0.02f",[self.deviceStatus doubleForKey:@"DeviceYaw"]);
                     NSLog(@"*xYaw is %d, yYaw is %d",xYaw,yYaw);
                     self.rotateLeft.hidden = YES;
                     if (xYaw >=300 && yYaw <=0) {
                         [self.rotateRight setFrame:CGRectMake(300, 0, 20, 20)];
                     }else{
                         [self.rotateRight setFrame:CGRectMake(xYaw, yYaw, 20, 20)];
                     }
                 }
             }

             if (rollOk == YES && pitchOk == YES && yawOk ==YES) {
                 self.orientationOkay.hidden = NO;
                 self.centerCircle.hidden = YES;
                 self.rollDot.hidden = YES;
                 self.pitchDot .hidden =YES;
                 self.yawDot.hidden = YES;
                 [self.clickTimer invalidate];
                 self.clickTimer = nil;
                 self.takePicButton.hidden = NO;
                 timerRunning = NO;
                 [self.motionManager stopDeviceMotionUpdates];
                 [self.deviceStatus removeObjectForKey:@"DeviceRoll"];
                 [self.deviceStatus removeObjectForKey:@"DevicePitch"];
                 [self.deviceStatus removeObjectForKey:@"DeviceYaw"];
                 [self.deviceStatus removeObjectForKey:@"DeviceAngle"];

             }else{

                 self.orientationOkay.hidden = YES;
                 if (flagger == YES) {
                     self.centerCircle.hidden = NO;
                 }
                 else{
                     self.centerCircle.hidden = YES;
                 }
             }
         }
     }else{
         self.rotateRight.hidden = YES;
         self.rotateLeft.hidden = YES;
         self.rollToL.hidden = YES;
         self.rollToR.hidden = YES;
         self.pitchToDown.hidden = YES;
         self.pitchToUp.hidden = YES;
         self.rollDot.hidden = NO;
         self.pitchDot .hidden =NO;
         self.yawDot.hidden = NO;
         [self.yawDot setFrame:CGRectMake(0, 390, 20, 20)];
         [self.rollDot setFrame:CGRectMake(0, 195, 20, 20)];
         [self.pitchDot setFrame:CGRectMake(150, 0, 20, 20)];

     }
     }];

如果需要任何进一步的细节，请告诉我。

任何建议或建议总是受欢迎的，:) 我是编程和 ios 的菜鸟。

谢谢！！

4

2 回答 2

5

我认为以下几点是管理任务所必需的：

  1. 首先，您需要对四元数有很好的了解（如果您已经与他们交上了朋友，请跳过此部分）。我推荐OpenGL:Tutorials:Using Quaternions to representation rotation或The Matrix and Quaternions FAQ。请记住，(x, y, z) 表示要围绕旋转的轴（未标准化），w = cos (alpha/2) 即大约代表旋转量。

  2. 由于CMQuaternion只是一个结构，因此很难进行所有计算。使用功能齐全的四元数类，而不是像cocoamath（您至少需要来自trunk的 Quaternion.h、.m 和 QuaternionOperation.m ）。

  3. 现在基本考虑：

    1. 两个四元数之间的差异（或有时称为除法）被定义为从一个方向到另一个方向的角位移可能是要走的路。它被定义为
      d = a -1 * b
      所以这表示从当前位置到目标位置的增量。

    2. 有了这个增量，您需要定义要满足的条件，以考虑达到目标方向。我的第一个想法是使用三角角。这可以通过以下计算的 d 四元数的 w 分量轻松检索：
      alpha = 2 * arccos (w)
      arccos 的域是有限的，但在这种情况下这应该不是问题，因为我们对小值特别感兴趣.

也许值得强调的是，每个 3D 旋转都有两个单位四元数表示，q和-q。这可能会令人困惑，但没关系。

更新： 所以一些伪代码看起来像：

CMQuaternion cmQ = attitude.quaternion;
// Get an instance of cocoamath's Quaternion for our currently reported quaternion
Quaternion current = [Quaternion initWithRe:(double)cmQ.w i:(double)cmQ.x j:(double)cmQ.y k:(double)cmQ.z];
// the complex conjugate and normalised to be on the safe side
Quaternion inverse = [current inverse];
// build the delta, assuming you have your stored direction as class member targetQuaternion
Quaternion diff = [inverse multiply:targetQuaternion];
float alpha = 2 * acos (diff.Re);
// maxDeltaAngle is your class member variable defining the angle from which you assume the position as restored (radians)
if (fabs (alpha) < maxDeltaAngle) {
    // do my fancy camera things
}

是的，一开始并不是那么微不足道。正如阿里在他的回答中所说，可视化也是一个重要问题。我的解决方案只是解决了原始数学部分。

于 2013-10-08T08:35:26.320 回答
1

我并不是说以下是您问题的解决方案，我不知道这将是多么用户友好，但我相信它值得一试。我看到了两个问题：你如何存储态度以及如何形象化它们。

贮存。我会将姿态保存为四元数或旋转矩阵；CMAttitude 两者都提供。（我个人更喜欢旋转矩阵而不是四元数，因为我认为旋转矩阵更容易理解。这只是个人喜好。）

可视化。您正在使用 3 个标记使手机保持与保存的相同的姿态。这 3 个标记来自 yaw、pitch 和 roll，有效地破坏了应用程序的稳定性。而不是这 3 个标记，我将可视化保存的姿态和当前姿态之间的旋转。一种方法是将旋转的 3 个基向量投影到手机屏幕上。旋转矩阵的好处是它们无需任何额外的计算就可以准确地为您提供这一点。例如，要可视化

| 1 0 0 |
| 0 1 0 |
| 0 0 1 |

旋转这个旋转矩阵表示，我只需要绘制从[0, 0, 0]到 (i) [1, 0, 0]、 (ii)[0, 1, 0]和 (iii)的 3 个箭头[0, 0, 1]。也就是说，我只需要绘制矩阵的行或列（也取决于您想要的行或列是否更好）。

要获得保存的旋转矩阵S和当前旋转矩阵之间的旋转，C您需要计算 C T S （用文字表示：C转置时间S）。如果您的旋转矩阵如上图所示，则您已将手机与保存的姿态对齐。

旋转矩阵的优秀教程是方向余弦矩阵 IMU：理论手稿。

另一种可视化保存的姿态和当前姿态之间的旋转的方法是将其转换为角轴形式。然后，我会将轴投影到手机屏幕上。用户首先将手机与轴对齐，然后需要围绕轴旋转以匹配保存的姿态。四元数基本上代表轴角形式，尽管以一种不平凡的方式。

根据您的需要，您需要做大量的进一步工作来改变这个想法；这绝对不是一个完整的答案。不过，我希望这会有所帮助。

于 2013-10-08T10:56:26.907 回答