. This method assumes that
the particles will lie in a stable position on the conveyor belt
so the thickness of the particle is viewed from the side and
the length and width are viewed from above. This
assumption is not completely true since particles have
several stable positions and the thinnest axis is not
necessarily perpendicular to the stable resting position.
Furthermore this method requires advanced equipment to
feed particles one at a time past the imaging point. A third
method allows particles to fall from a rotating cylinder [16].
The particles are imaged as they fall. This method assumes
that the thickness of the particles will be oriented parallel to
the rotating cylinder. This is not always true since the
particles tend to rotate during fall. All of these methods take
several individual images of each particle in the sample.