Rotation doesn't work with JointOrientation from kinect in Unity3D 5

Questions & Answers
1

A weird thing happen to my code, I don’t know why I worked like this, but it did.

My code is like this:

            // Getting joint orientation data from kinect 
            // and construct it with Unity Quaternion
            Kinect.Vector4 targetRotaV4 = body.JointOrientations[jt].Orientation;
            Quaternion targetRotaQ = new Quaternion(targetRotaV4.X, targetRotaV4.Y, targetRotaV4.Z, targetRotaV4.W);
            Debug.Log("target rotation: " + targetRotaQ); // it did print something

            // Rotate the gameobject from its local rotation 
            // to the rotation I got from kinect
            jointObj.localRotation = Quaternion.RotateTowards(jointObj.localRotation, targetRotaQ, 45.0f);
            Debug.Log("Joint Object rotation: " + jointObj.localRotation); 
            // It did print value, too, not just (0, 0, 0, 0), 
            // but in the game, the gameobject didn't rotate, and the rotation didn't change in properties which kept 0

            // But!! When I ran the following code, it rotated! Everything looked good.
            /*
            Quaternion testRote = new Quaternion(0.1f, 0.1f, 0.1f, 0.1f);
            jointObj.localRotation = Quaternion.RotateTowards(jointObj.localRotation, testRote, 15);
            Debug.Log("Joint local rotation" + jointObj.localRotation);
            */

So my question is, why! Why the rotation couldn’t work with my JointOrientation data from kinect which I did get the data because I print the value and it was not null or 0.

Plz help me out!

2

Because the Kinect quaternions seem to assume that any bone points to the sky before rotating,
I turned the bones of my model to the sky before applying the quaternions.

I think you observed your model was jerky and unstable because the quaternions rotated wrongly oriented objects.
Suppose a quaternion rotates objects around y-axis and consider rotating the following two objects by it.

leftArm.transform.rotation = ElbowLeft * Quaternion.AngleAxis(90, new Vector3(0, 1, 0)) * Quaternion.AngleAxis(-90, new Vector3(0, 0, 1));