A computerized device for driving assistance comprises a memory (4) designed to receive data point cloud data (8) in which a point cloud associates, for a given instant, points each having coordinates in a plane associated with the point cloud and a value denoting a height. The device furthermore comprises a calculator (6) designed to access the memory (4) and, for a given point cloud, to calculate data on the probability of belonging to a reference surface, associated with each point of the data point cloud, on the one hand, and node data associating a value denoting a height (hi) and two values indicating a slope in a plane associated with the plane of the given point cloud, on the other hand, by determining a Gaussian random conditional field by way of the data point cloud data (8) corresponding to the given point cloud, which Gaussian random conditional field is represented by a mesh of nodes in said associated plane, which nodes are defined by the node data, and to return the data on the probability of belonging to a reference surface and/or at least some of the node data and values denoting a height.