  We propose a calculus integrating two calculi well-known in Qualitative
Spatial Reasoning (QSR): Frank's projection-based cardinal direction calculus,
and a coarser version of Freksa's relative orientation calculus. An original
constraint propagation procedure is presented, which implements the interaction
between the two integrated calculi. The importance of taking into account the
interaction is shown with a real example providing an inconsistent knowledge
base, whose inconsistency (a) cannot be detected by reasoning separately about
each of the two components of the knowledge, just because, taken separately,
each is consistent, but (b) is detected by the proposed algorithm, thanks to
the interaction knowledge propagated from each of the two compnents to the
other.
