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

ethzasl_sensor_fusion

asked 2014-06-24 20:14:43 -0600

giovanni.sutanto
56 ●2 ●2 ●6

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

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answered 2014-06-25 21:55:41 -0600

giovanni.sutanto
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Hi Folks,

I eventually contacted Stephan Weiss personally thru e-mail. This is his respond: "The naming of the variables is not very consistent, unfortunately. q_wv should be q_vw, hence the confusion."

Hope this helps!

Cheers,

Giovanni

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Asked: 2014-06-24 20:14:43 -0600

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