PoseMath is a utility that makes it easy to work with PyKDL.Frame‘s. It can work with poses from a variety of sources: tf.Transformer.lookupTransform(), opencv and ROS messages. It has utility functions to convert between these types and the PyKDL.Frame pose representation.
>>> from geometry_msgs.msg import Pose
>>> import tf_conversions.posemath as pm
>>> import PyKDL
>>>
>>> msg = Pose()
>>> msg.position.x = 7.0
>>> msg.orientation.w = 1.0
>>>
>>> frame = PyKDL.Frame(PyKDL.Rotation.RPY(2, 0, 1), PyKDL.Vector(1,2,4))
>>>
>>> res = pm.toTf(pm.fromMsg(msg) * frame)
>>> print res
((8.0, 2.0, 4.0), (0.73846026260412856, 0.40342268011133486, 0.25903472399992566, 0.4741598817790379))