A grain transfer system for automatically controlling the transfer of grain from a harvesting machine to a receiving container while the harvesting machine and the receiving container are situated in generally side by side relative positions, comprising: an unloading system including an unloading tube having a discharge nozzle, the unloading system configured and operable for directing a flow of grain from the harvesting machine to the receiving container through the discharge nozzle at a known flow rate, characterised in that the grain transfer system further comprises: a sensing system including a reading device mounted near or on the nozzle and a first data device disposed in or in predetermined relation to a first region of the receiving container through an nth data device disposed in or in predetermined relation to an nth region of the receiving container, respectively, the first data device including at least information representative of a location of the first region of the receiving container and the nth data device including at least information representative of a location of the nth region of the receiving container, respectively, the reading device being configured to acquire information from the first data device through the nth data device, the sensing system being configured to determine positions of the nozzle relative to the first region through the nth region as a function of time; a modeling system including a processor configured to communicate with the sensing system and to model a real time fill level profile for at least one region (40, 44) of the receiving container as a function of the positions of the nozzle as a function of time and the known flow rates of grain; a display system configured to display information representative of the modeled fill level profile in real time; and a controller in communication with the modeling system and configured to automatically provide a control indication for adjusting the position of the nozzle relative to the first region through the nth region for directing the flow of grain to each of the n regions, respectively, for achieving a generally even fill of the receiving container. an unloading system including an unloading tube having a discharge nozzle, the unloading system configured and operable for directing a flow of grain from the harvesting machine to the receiving container through the discharge nozzle at a known flow rate, a sensing system including a reading device mounted near or on the nozzle and a first data device disposed in or in predetermined relation to a first region of the receiving container through an nth data device disposed in or in predetermined relation to an nth region of the receiving container, respectively, the first data device including at least information representative of a location of the first region of the receiving container and the nth data device including at least information representative of a location of the nth region of the receiving container, respectively, the reading device being configured to acquire information from the first data device through the nth data device, the sensing system being configured to determine positions of the nozzle relative to the first region through the nth region as a function of time; a modeling system including a processor configured to communicate with the sensing system and to model a real time fill level profile for at least one region (40, 44) of the receiving container as a function of the positions of the nozzle as a function of time and the known flow rates of grain; a display system configured to display information representative of the modeled fill level profile in real time; and a controller in communication with the modeling system and configured to automatically provide a control indication for adjusting the position of the nozzle relative to the first region through the nth region for directing the flow of grain to each of the n regions, respectively, for achieving a generally even fill of the receiving container.