Sensor quaternion to Unity conversion [duplicate]

Question

I want to convert rotations given as quaternion from sensors to Unity. The sensors (documentation here) axis are the following ones:

Unity is the following one:

I don't know how to map axis other than Z is up for the axis. Note that I don't really mind if I have a global rotation offset. I just want the sensors (they are multiple ones) relative orientation to be the same in Unity that in real life

Given this other answer I think the following code should to the transformation:

Quaternion ConvertToUnity(Quaternion input) {
    return new Quaternion(
        -input.y,
        -input.z,
        -input.x,
        input.w
    );
}

Is that correct?

Answer 1

Summarizing the diagram:

Attribute      Unity Coordinates     Sensor Coordinates
-------------------------------------------------------
Right                 +X                   -Y
Up                    +Y                   +Z
Forward               +Z                   +X
Handedness        Left Handed          Right Handed

So to convert to Unity...

• Unity's x axis should use the sensor's y axis, negated
• Unity's y axis should use the sensor's z axis
• Unity's z axis should use the sensor's x axis
• ...and since we're changing handedness, we need to negate the angle, which means negating all imaginary components of the quaternion and leaving the real part w unchanged.

So you were close, you just missed the double-flip of the sign on the first argument:

Quaternion ConvertToUnity(Quaternion sensorQuaternion) {
    return new Quaternion(
         sensorQuaternion.y, // -1 * (   Right = -Left    )
        -sensorQuaternion.z, // -1 * (      Up =  Up      )
        -sensorQuaternion.x, // -1 * ( Forward =  Forward )
         sensorQuaternion.w
    );
}