6-d polyhedral models give a periodic description of aperiodic quasicrystals.
There are powerful tools to describe their structural surface properties. Basis
of the model for icosahedral quasicrystals are given. This description is
further used to interpret high resolution STM images of the surface of i-AlPdMn
which surface preparation was followed by He diffraction. It is found that both
terrace structure and step-terrace height profiles in STM images can be
consistently interpreted by the described model