Process and apparatus for modelling an ambient field

Modelling an ambient field of an object, in particular of a vehicle, comprises providing at least one cell 1 having a unique identification, neighbourhood relationships whichfor each direction 11, 12 in which further linking cells may be located includes an identification of an existing adjacent cell or information indicating no adjacent cell is present, and items of occupancy information that are formed by a spatial discretisation of the cell. The current position of the object and an obstacle is determined in the environment of the object and the occupancy value or occupancy probability of the discrete obstacle position is changed. An intermediate position between the object and the obstacle is changed to indicate a vacant position. The occupancy values can indicate, occupied, vacant and unknown and the cells may represent a two dimensional or three dimensional environment occupancy map. Information about the environment may be obtained by sensors on the vehicle.