  The volume tensor provides robust estimate of object shape and orientation in
space. The tensor is estimated from 3D data set by the Fakir probe, an
interactive method using intersections of the objects boundary with a virtual
lines. The method thus can be applied to objects that cannot be segmented
automatically. Marking the intersections instead of segmenting the whole object
reduces the workload required for obtaining sufficiently precise results. We
present theoretical results on the variance of estimate of integrals by
systematic sampling that enable calculation of the shape estimate precision. To
demonstrate the ability of Fakir technique, we measure the changes in shape and
orientation of pheasant brain compartments during development.
