Why quaternion need to be conjugated first before conversion to rotation matrix?

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Hi Stephan,

I am following the tutorial, but I have one thing that I still don't understand: Why quaternion need to be conjugated first before conversion to rotation matrix? For example in pose_sensor.cpp inside ssf_updates: C_wv = state_old.q_wv_.conjugate().toRotationMatrix(); Why it's not just: C_wv = state_old.q_wv_.toRotationMatrix();

I thought quarternion q_wv_ is already in the same reference frame as C_wv, as its name suggests???

Please give me some lights. Thanks a lot!

Best Regards,

Giovanni