A system for determining one or more attributes of a target object being transported by a conveyance mechanism, the conveyance mechanism having a traverse measurement and a longitudinal measurement and a direction of transport that corresponds to the longitudinal measurement, and the target object having a diameter in a plane substantially parallel to a conveying plane of the conveyance mechanism, the system comprising: - a first photoelectric sensor that emits a first light ray; - a second photoelectric sensor that emits a second light ray, the first and second photoelectric sensors (114, 116) being positioned at respective angles (α 1, α 2) relative to the direction of transport such that each of the first and second light rays (126, 128) extends across a width of the conveyance mechanism and such that the first and second light rays (126, 128) cross one another at a first intersection point; and - a third photoelectric sensor that emits a third light ray, the third light ray extending across the width of the conveyance mechanism, crossing one of the first light ray and the second light ray at a second intersection point and being substantially parallel to the other one of the first light ray and second light rays; wherein a speed at which the conveyance mechanism transports the target object is unknown but constant, whereby said system comprises means configured to determine said speed using the third light ray and the one of the first light ray and second light ray which is parallel to the third light ray; wherein based, at least in part, upon a respective time of interruption of each of the first and second light rays (126, 128) by the target object, a location of interruption of each of the first and second light rays (126, 128) by the target object relative to the first intersection point and the determined speed, said means are further configured to determine the location of the target object relative to the conveyance mechanism, the first photoelectric sensor and the second photoelectric sensor. - a first photoelectric sensor that emits a first light ray; - a second photoelectric sensor that emits a second light ray, the first and second photoelectric sensors (114, 116) being positioned at respective angles (α 1, α 2) relative to the direction of transport such that each of the first and second light rays (126, 128) extends across a width of the conveyance mechanism and such that the first and second light rays (126, 128) cross one another at a first intersection point; and - a third photoelectric sensor that emits a third light ray, the third light ray extending across the width of the conveyance mechanism, crossing one of the first light ray and the second light ray at a second intersection point and being substantially parallel to the other one of the first light ray and second light rays; wherein a speed at which the conveyance mechanism transports the target object is unknown but constant, whereby said system comprises means configured to determine said speed using the third light ray and the one of the first light ray and second light ray which is parallel to the third light ray; wherein based, at least in part, upon a respective time of interruption of each of the first and second light rays (126, 128) by the target object, a location of interruption of each of the first and second light rays (126, 128) by the target object relative to the first intersection point and the determined speed, said means are further configured to determine the location of the target object relative to the conveyance mechanism, the first photoelectric sensor and the second photoelectric sensor. wherein a speed at which the conveyance mechanism transports the target object is unknown but constant, whereby said system comprises means configured to determine said speed using the third light ray and the one of the first light ray and second light ray which is parallel to the third light ray; wherein based, at least in part, upon a respective time of interruption of each of the first and second light rays (126, 128) by the target object, a location of interruption of each of the first and second light rays (126, 128) by the target object relative to the first intersection point and the determined speed, said means are further configured to determine the location of the target object relative to the conveyance mechanism, the first photoelectric sensor and the second photoelectric sensor.