Method for determining the length of a queue

Abstract

Method for determining the length of a queue of objects in a predefined region having at least one entrance and at least one exit, in the course of which errors in the acquisition of objects entering or exiting the region are corrected during the determination of the length of the queue. In a first step, a specific entry signature E of each object entering the predefined region through the at least one entrance is determined with the aid of at least one first image sensor. Thereafter, the specific entry signature E is stored in an entry list of a calculation unit, each entry signature E being provided with an index value i reflecting the temporal sequence of the entries. In addition, a value L reflecting the length of the queue of the objects is increased by one. Furthermore, a specific exit signature A of an object exiting the predefined region through the at least one exit is determined with the aid of at least one second image sensor, the specific exit signature A being stored in an exit list of a calculation unit as exit signature Awith index value j=0. The index value of exit signatures Aalready present in the exit list is respectively increased by one, and exit signatures Awhich have an index value j that is greater than a predeterminable value M are deleted from the exit list. Subsequently, similarity values Cfor −N≦n≦+N are calculated with the aid of the calculation unit, N being a predeterminable value which defines a specific number N of entry signatures of objects which, before or after the object with the entry signature Ewhich next exits the predefined region on the basis of the length of the queue L, will exit or have already exited the predefined region. In the process, similarity metrics Uare respectively calculated between an exit signature Aand an entry signature E, M running from 0 to M, and added to C. The value L is decremented by the value one. Subsequently, the similarity values Care compared with the similarity value C. The value L is corrected by adding the index value x given the presence of a value Cwith index value n=x that indicates a higher similarity than the similarity value C.