Method and processing unit for determining the size of an object

A method () for determining the value of a size of an object () is described. The method () comprises determining () an occupancy grid () indicating evidence that individual cells () are vacant or occupied by the object (). Further, the method () comprises determining () a subset of cells () associated with the object (). Further, the method () comprises detecting () two opposing bounding edges of the object (), and determining () a measurement value of the size of the object () based on the distance between the detected edges of the object (). The method () further comprises determining () a quality measure indicating how well the two opposing edges of the object () could be detected, and determining () a measurement probability distribution of the size of the object () dependent on the quality measure. Further, the method () comprises determining () a cumulative probability distribution based on the measurement probability distribution, and determining () a value of the size of the object () based on the cumulative probability distribution.