about angle axis

[Jianxiong Xiao]

Hi guys,

I have a very naive question that puzzles me for the whole day!


I have a 3D point, X = [-2.1617 -1.49118 3.61829]
and a rotation matrix:
RotMat = [
0.9288 0.0339 -0.3690
0.3695 -0.1566 0.9159
0.0267 0.9871 0.1580 ]

I transform the point X by the rotation RotMat and get RotMat * X = [
-3.3935 2.7488 -0.9580 ].

But if I covert RotMat to angle axis representation using
RotationMatrixToAngleAxis, I got.
AArep = [ 0.2316 -1.2870 1.0915 ]
and then use AngleAxisRotatePoint to rotate the point X,
I got [ -0.9921 -4.3594 -0.0117 ],

Which is a very different answer!

I am so lost now. Please help me. Thanks a lot!

--
Best,
Jianxiong

[Sameer Agarwal]

Check  the calling conventions on these functions. I think for silly historical reasons one is probably column major and the other is row major. Use the matrix adapters to get uniform access.

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[Jianxiong Xiao]

Thanks for the prompt response, Sameer!

I think I figured out the answer, inspired by your comment. My
rotation matrix is not a valid matrix. det(RotMat) = -1
I think I messed up some left hand and right hand coordinate
conversion in my system, and gave ceres the wrong matrix.
Thanks a lot!

--
Best,
Jianxiong

[Sameer Agarwal]

You are welome. I am glad my non-answer could help you :)

Sameer