A device measures positions of a plurality of objects. The device comprises a memory arranged to store positioning data for a plurality of objects having mutual constant positions, an input interface arranged to obtain measurement data of relative positions for at least a subset of the plurality of objects, and a processor arranged to calculate an adapted measurement position for at least one of the objects of the subset of the plurality of objects by correlating the measured relative positions for the at least a subset of the plurality of objects with the acquired positioning data. Another device provides position data of a plurality of objects. The device comprises an interface arranged to acquire an image of the plurality of objects, a position of an apparatus acquiring the image, and a position relationship between the respective object and the determined position, an image processing device arranged to identify respective object from the image, a processor arranged to assign a position estimate for each of at least a subset of the identified objects by calculating the position estimates from the position of the apparatus and the position relationship to the respective object. Corresponding methods and computer programs are also disclosed.Fig. 1 elected for publication
