Hi! On 01/11/2011 01:56 PM, Raphael Favier wrote: > I finally started to get something working using KDL and its rotation > objects. Thanks! > Still, there are a few cases when the value of yaw pitch and roll cannot be > guessed. > > Anyway, all I wanted to do was to get the Z rotation value of one observed > frame. If feels strange to have gone all the way with using KDL for that. Did you have a look at ? That's what I usually use for these transformations and it wraps most code nicely for you without depending on KDL. "createQuaternionFromRPY" could be useful for you, and you can also use "quat.getRPY(roll, pitch,yaw)" as a tf::Quaternion is simply a bullet quaternion. Cheers, Armin -- Armin Hornung Humanoid Robots Lab, Albert-Ludwigs-Universität Freiburg Contact: http://www.informatik.uni-freiburg.de/~hornunga