tf.transformations.quaternion_from_matrix() is misleading

[jbohren]

The tf.transformations.quaternion_from_matrix() function says it returns a quaternion from a rotation matrix, but it fails if you give it an actual rotation matrix (element of SO(3)). Instead it requires that the input "rotation matrix" is a 4x4 matrix (element of SE(3)).

If you try passing it a 3x3 rotation matrix, you get the following error:

  File "/opt/ros/hydro/lib/python2.7/dist-packages/tf/transformations.py", line 1206, in quaternion_from_matrix
    M = numpy.array(matrix, dtype=numpy.float64, copy=False)[:4, :4]
IndexError: too many indices

I understand the utility of extracting a quaternion directly from a rigid transform, but it should also accept an actual rotation matrix as input.

https://github.com/ros/geometry/blob/indigo-devel/tf/src/tf/transformations.py#L1196
Related to #49

[tfoote]

This is an external library pulled in for convenience. I don't want to diverge from it's API. We've had bad experiences with that in the past.

[jbohren]

This is an external library pulled in for convenience. I don't want to diverge from it's API. We've had bad experiences with that in the past.

Alright, would a PR that fixes the documentation be welcomed?

[tfoote]

Definitely.

On Tue, May 20, 2014 at 2:36 PM, Jonathan Bohren
[email protected]:

This is an external library pulled in for convenience. I don't want to
diverge from it's API. We've had bad experiences with that in the past.

Alright, would a PR that fixes the documentation be welcomed?

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[tfoote]

Closing this as #49 would be adequate.