探戈项目:确定相交点平面模型对是否与重力对齐

Question

剧透警报：我不确定我是否以正确的方式使用四元数。

我使用TangoSupport.fitPlaneModelNearClick(...)方法得到了一个IntersectionPointPlaneModelPair pair。我现在想知道这个平面是否与重力对齐（或多或少）。我的方法是从pair.planeModel创建一个Quaternion（Rajawali），从ScenePoseCalculator.TANGO_WORLD_UP创建另一个，并旋转0.0，将它们相乘，确定原始和乘积之间的角度：

IntersectionPointPlaneModelPair pair= TangoSupport.fitPlaneModelNearClick(...);
double x = 0.05; // subject to change
double[] p = pair.planeModel;
Quaternion plane = new Quaternion(p[0], p[1], p[2], p[3]);
plane.normalize();
Quaternion gravity = Quaternion(ScenePoseCalculator.TANGO_WORLD_UP.clone(), 0.0);
Quaternion product = plane.multiply(gravity);
if (plane.angleBetween(product) > x){
     ...   
}

然而，这不起作用，因为product与plane完全相同。提前感谢！

Answer 1

我发现我对Quaternion s有错误的理解。我还发现了这个平面角度计算公式。因此，我将我的实现更改为以下内容：

编辑：新答案（下面是旧答案）

private boolean isAlignedWithGravity(IntersectionPointPlaneModelPair candidate,
                                         TangoPoseData devicePose, double maxDeviation) {
    Matrix4 adfTdevice = ScenePoseCalculator.tangoPoseToMatrix(devicePose);
    Vector3 gravityVector = ScenePoseCalculator.TANGO_WORLD_UP.clone();
    adfTdevice.clone().multiply(mExtrinsics.getDeviceTDepthCamera()).inverse().
            rotateVector(gravityVector);
    double[] gravity = new double[]{gravityVector.x, gravityVector.y, gravityVector.z};
    double angle = VectorUtilities.getAngleBetweenVectors(candidate.planeModel, gravity);
    // vectors should be perpendicular => 90° => PI / 2 in radians
    double target = Math.PI / 2; 
    return (Math.abs(target - angle) <= maxDeviation);
}

在类VectorUtilities:中

/**
 * Calculates the angle between two planes according to http://www.wolframalpha
 * .com/input/?i=dihedral+angle
 */
public static double getAngleBetweenVectors(double[] a, double[] b) {
    double numerator = 0;
    for (int i = 0; i < Math.min(a.length, b.length); i++){
        numerator += a[i] * b[i];
    }
    double denominator = getLength(a) * getLength(b);
    return Math.acos(numerator / denominator);
}

public static double getLength(double[] vector) {
    double sum = 0.0;
    for (double dimension : vector) {
        sum += (dimension * dimension);
    }
    return Math.sqrt(sum);
}

---

老答案

private boolean isAlignedWithGravity(IntersectionPointPlaneModelPair pair,
                                     TangoPoseData devicePose) {
    Matrix4 adfTdevice = ScenePoseCalculator.tangoPoseToMatrix(devicePose);
    Vector3 gravityVector = ScenePoseCalculator.TANGO_WORLD_UP.clone();
    adfTdevice.clone().multiply(mExtrinsics.getDeviceTDepthCamera()).inverse().
            rotateVector(gravityVector);
    double[] gravity = new double[]{gravityVector.x, gravityVector.y, gravityVector.z};
    double angle = getAngleBetweenPlanes(pair.planeModel, gravity);
    Log.d(TAG, "angle: " + angle);
    if (angle < 0.1) {
        return false;
    }
    return true;
}
/**
 * Calculates the angle between two planes according to http://mathworld.wolfram
 * .com/DihedralAngle.html
 */
private double getAngleBetweenPlanes(double[] a, double[] b) {
    double numerator = Math.abs(a[0] * b[0] + a[1] * b[1] + a[2] * b[2]);
    double aFactor = Math.sqrt(a[0] * a[0] + a[1] * a[1] + a[2] * a[2]);
    double bFactor = Math.sqrt(b[0] * b[0] + b[1] * b[1] + b[2] * b[2]);
    double denumerator = aFactor * bFactor;
    double result = Math.acos(numerator / denumerator);
    return result;
}