Quaternion rotations not working right

Hi all,

I’m using standard quaternion routines to convert to/from Euler and to 4x4 rotation matrices. But I’m observing some bizarre stuff.

For instance, when I alter yaw (rotation about y axis), the rotation matrix that I get using a quaternion intermediate rotates instead about the z axis (roll).

Has anyone seen this problem before and have a clue as to what might be going wrong? I’m putting too many hours into this and seeing no improvement.


I have broad experience using quaternions, Euler angles and rotation matrices (direction cosine matrices). If you are a professional developer I am available for fee based consulting; if you are a student I can offer casual question answering support.
reply to nhughes1ster@gmail.com

Double check your quaternion equation: http://www.flipcode.com/documents/matrfaq.html#Q47

Maybe there is a typo there. I created a video tutorial showing how to use Quaternions here if you would like to take a look http://www.marek-knows.com/downloadSection.php?Topic=Math&pg=1#Math8

You can download the demo program from my forum