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I have a couple of IMUs (rotation devices), I'm trying to attach them on fingers and make a glove. I get confused because I don't have a good way to think about rotation in the physical and virtual world.

Right now, the way I'm thinking about it is that, in the physical world, there is a world coordinate (XYZ). The IMU's rotation quaternion is probably based on that. I'm also thinking that each IMU has slightly different physical world coordinate from one other (because they give slightly different quaternion values when they point the same direction). In the virtual world, each IMU has another virtual world coordinate system.

I'm confusing that maybe it's just one coordinate system that cannot be separated as world or virtual? I'm not sure how to think about all of this and it makes it hard to ask questions.

Please tell me which concepts/terminologies I need to understand to gain intuition about how to think rotations in the physical and virtual world.

The motivation? I am trying to calibrate my glove (each finger has one IMU, the palm has one IMU) so that it shows correct hand model in the Unity scene. But it's hard to wrap my head around it.

off99555
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    Remember that all transfromation (translation, rotation ) is a transformation from one coordinate frame into other coordinate frame (CF). So you need to define for every transformation, "from" and "into" CF. And it is usual situation , when physical (world) CS is indentical to virtual CF – minorlogic Oct 22 '18 at 13:12

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The main concept to understand about how Unity handles the rotation of your object is that every element has a World rotation and a Local rotation.

The local rotation is the rotation of the object relative to it's parent, and the world rotation is the rotation to the object relative to the root of your scene.

These variables are stored as Quaternions, but if you want to work effectively with them, you will probably want to use Vector3 values. This is what eulerAngles are for :

The Euler angles of your quaternion are actually the XYZ values of your rotation you mentionned in your post.

alpha_rats
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