Talk:Conversion between quaternions and Euler angles

Needs to be explicit that this rotates a body

I was looking for the euler 123 to quaternion conversion that will rotate from one frame to another. The euler to quaternion conversion shown on the page does not line up with the SpinCalc euler 123 conversion from Matlab Central. Maybe the equation on the page rotates the points in a body while keeping the reference frame the same?

From SpinCalc.m with scalar at 4th position

Q=[s1.*c2.*c3+c1.*s2.*s3,   c1.*s2.*c3-s1.*c2.*s3,   c1.*c2.*s3+s1.*s2.*c3,   c1.*c2.*c3-s1.*s2.*s3];  —Preceding unsigned comment added by 128.157.160.13 (talk) 22:42, 3 September 2009 (UTC)[reply]

Are the "Euler angles" in this article really Tait-Bryan_angles?

Canonical form of quaternion?

The equation presented for conversion from Euler angles to Quaternion has several discontinuities that are not necessarily present in the Quaternions themselves.

For instance, for the Euler angles (0,0,-180) and (0,0,180), the conversion would produce the quaternions (0,0,0,1) and (0,0,0,-1). These refer to the same attitude, but linear interpolation or slerp between them would not work well.

It appears that the proper way to handle this is to compute the cosine of the angle between the quaternions (via the dot product) and if this is less than zero to negate one of the quaternions.

Which definition of the Euler angles is being employed in this page?

Absolutely no mention is given as to which (of the 12 possible) definitions of the Euler angles are being employed in this discussion.

Order of angles specified?

Does the order of rotation (described as "in the order yaw, pitch, roll" in first section) match the matrix given in "Rotation matrices" section? That matrix corresponding to rotation with Euler angles can be given by (Rz (Ry Rx)). Isn't that in the order x,y,z instead? — Preceding unsigned comment added by 144.212.114.62 (talk) 22:25, 2 December 2006 (UTC)[reply]

Matrix convention

It should be stated what the convention being used for the rotation matrices is. Is it supposed to be pre-multiplied by a row vector or post-multiplied by a column vector? Icalanise (talk) 23:18, 21 October 2008 (UTC)[reply]

someone seems to be confused. "The orthogonal matrix (post-multiplying a column vector) corresponding to a clockwise/left-handed rotation by the unit quaternion q=q_0+iq_1+jq_2+kq_3 is given by the inhomogeneous expression"

If you are using a column vector then the matrix is on the left of the vector and that would appear to be pre-multiplying, not post-multiplying.Eregli bob (talk) 12:17, 28 October 2012 (UTC)[reply]

Euler Conversion

Is the displayed formula correct? The link in the singularity section (http://www.euclideanspace.com/maths/geometry/rotations/conversions/quaternionToEuler/) displays a different formula ... —Preceding unsigned comment added by 83.171.153.247 (talk) 18:07, 1 March 2009 (UTC)[reply]

Could this be because the article uses a left-handed rotation (as specified on the paragraph giving the matrix for x-y-z convention rotation) ? I'mt not sure, but I think there are a LOT of different ways to convert quaternions to euler angles. See http://www.cgafaq.info/wiki/Euler_angles_from_matrix for example.

Basically, if someone knowledgeable enough could rewrite the part on conversion to discuss the various possibilities, that would be very nice. 81.63.104.6 (talk) 20:22, 8 May 2012 (UTC)[reply]

Matrices and handedness

The matrices given are for left-handed systems, whereas the drawing uses a right-handed convention. There is no way a beginner in the field can make sense of what is explained. Sam Hocevar (talk) 11:21, 30 April 2012 (UTC)[reply]

The reference does not exist anymore!

As above