1. A vehicle, comprising: a structure defining an interior space for containing one or more objects; and an arrangement mounted on said structure for determining whether an object is present in said interior space, said arrangement comprising: at least one optical imaging device arranged to receive images of said interior space defined by said structure; and a processor coupled to said at least one optical imaging device and arranged to determine whether one or more objects are present in said interior space and when one or more objects are determined to be present, to obtain information about the object or objects, whereby said processor is arranged to distinguish between different objects or different arrangements of objects.