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Rotation angles from matrix

Started by jtech Oct 1, 2001 at 2:43 PM 2 replies 900+ views

Original Post

Oct 1, 2001 at 2:43 PM

Give a 3x3 rotation matrix that was created using a concatentation order of R=X*Y*Z, how do you extract the rotation angles (x,y,z)? I''ve read you should convert the matrix to a quaternion first, but the explanation didn''t include any code. Anyone have some code handy to do this?

LilBudyWizer

Oct 1, 2001 at 8:22 PM

I''m not thinking too clearly tonight, but either the rows or columns of your 3X3 matrix are vectors representing the direction and scale of the x, y and z axes. If you use m*v then it is the rows and if you use v*m then it is the columns. That should at least give you a starting point.

jtech

Oct 2, 2001 at 2:32 PM

I can easily get the up, right, and direction vectors from a
rotation matrix (it's just the rows or columns of the matrix),
but I think I would be worst off then trying to figure out
the (rx,ry,rz) rotation angles that created the matrix in
the first place.

Maybe I should ask, how do you arbitrarily extract the
rotation angles from a quaternion?

Edited by - jtech on October 2, 2001 3:33:28 PM

jtech

Oct 2, 2001 at 3:14 PM

Got it!

Gramphics Gems IV: Eulerang.c, Eul_FromHMatrix and Eul_FromQuat.

Cool, both ways.

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