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## Main Question or Discussion Point

Hi All,

I think this is right, but not sure after doing some of the maths.

If I have two rotated objects...lets say two sticks...and each has a rotation, in quaternions q0 and q1.

Now the difference, can be calculated as

qdiff = q0 * Conjugate( q1 )

Okay?

Of course both my object quaternions are normalized rotation quaternions.

But if I calculated the axis angle for my qdiff, I would have guess it to give the shortest angle error to rotate one to the other?...and the axis would be that by which its rotated to get it?

But I found after some debugging it doesn't seem right...if I work out the rotation angle on the two sticks, the rotation axis is different, and if I do the dot product on the two sticks to get the minimum angle to rotate one to the other, its different than what my qdiff axis angle value gives.

Is there something I' missing?

Many Thanx,

Ben.

I think this is right, but not sure after doing some of the maths.

If I have two rotated objects...lets say two sticks...and each has a rotation, in quaternions q0 and q1.

Now the difference, can be calculated as

qdiff = q0 * Conjugate( q1 )

Okay?

Of course both my object quaternions are normalized rotation quaternions.

But if I calculated the axis angle for my qdiff, I would have guess it to give the shortest angle error to rotate one to the other?...and the axis would be that by which its rotated to get it?

But I found after some debugging it doesn't seem right...if I work out the rotation angle on the two sticks, the rotation axis is different, and if I do the dot product on the two sticks to get the minimum angle to rotate one to the other, its different than what my qdiff axis angle value gives.

Is there something I' missing?

Many Thanx,

Ben.

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