  Evidential grids have been recently used for mobile object perception. The
novelty of this article is to propose a perception scheme using prior map
knowledge. A geographic map is considered an additional source of information
fused with a grid representing sensor data. Yager's rule is adapted to exploit
the Dempster-Shafer conflict information at large. In order to distinguish
stationary and mobile objects, a counter is introduced and used as a factor for
mass function specialisation. Contextual discounting is used, since we assume
that different pieces of information become obsolete at different rates. Tests
on real-world data are also presented.
