[vtkusers] Question about object rotation

[Rienks R.J. (Rutger)]

Hello !
I'm working on a project to visualize head movements. I'm obtaining data
from a flock of bird sensor connected
to someone's head. I'd like to map the data (x,y,z, Azimuth, Elevation,
Roll) onto the position and angles of
the fran_cut face provided with VTK. I'm able to move the orientation of
the head, but the rotation axes are not
defined the way I'd like to have them. Does anyone know how I can define
rotation axes through an object. 
My best results so far come with something like
actor->SetOrigin(actor->GetCenter()). But that is not exactly as
I'd want it.  Since nodding and turning comes from the center bottom,
where as "getting your eyes vertical" should rotate
somewhere on an axes through the nose.. 

Thanks in advance !

Rutger