An apparatus for surface treating particulate material with surface treatment particles includes a substantially cylindrical body having a top, bottom and sidewall. Motion vectors in the global motion compensation are found by the interpolation andor extrapolation of the motion vectors of a plurality of representative points 602, 603 and 604 having particular features in the spatial distance thereof. Such N material is useful as a substrate for epitaxial growth of Group III-V nitride device structures thereon.