  We propose a new recursive method for simultaneous estimation of both the
pose and the shape of a three-dimensional extended object. The key idea of the
presented method is to represent the shape of the object using spherical
harmonics, similar to the way Fourier series can be used in the two-dimensional
case. This allows us to derive a measurement equation that can be used within
the framework of nonlinear filters such as the UKF. We provide both simulative
and experimental evaluations of the novel techniques.
