  The cross covariogram g_{K,L} of two convex sets K, L in R^n is the function
which associates to each x in R^n the volume of the intersection of K with L+x.
  The problem of determining the sets from their covariogram is relevant in
stochastic geometry, in probability and it is equivalent to a particular case
of the phase retrieval problem in Fourier analysis. It is also relevant for the
inverse problem of determining the atomic structure of a quasicrystal from its
X-ray diffraction image.
  The two main results of this paper are that g_{K,K} determines
three-dimensional convex polytopes K and that g_{K,L} determines both K and L
when K and L are convex polyhedral cones satisfying certain assumptions. These
results settle a conjecture of G. Matheron in the class of convex polytopes.
  Further results regard the known counterexamples in dimension n>=4. We also
introduce and study the notion of synisothetic polytopes. This concept is
related to the rearrangement of the faces of a convex polytope.
