Crop container monitoring

A crop container monitor for monitoring a fill-state during a harvesting operation, the crop container monitor comprising:

• an open-top crop container comprising a first wall, a second wall opposite the first wall, a third wall extending between the first wall and the second wall, and a fourth wall opposite the third wall and extending between the first wall and the second wall such that the first wall, the second wall, the third wall, and the fourth wall define an opening at a top of the open-top crop container through which harvested crop discharged from a harvesting vehicle enters and interior of the open-top crop container;
• at least one radiation sensor positioned at an upper end of one of the first wall, the second wall, the third wall, or the fourth wall of the open-top crop container to receive radiation reflected off the harvested crop within the interior of the open-top crop container;
• and
• a controller that:
• receives a sensing signal from the at least one radiation sensor, wherein the sensing signal is representative of the received radiation;
• determines a propagation distance from the at least one radiation sensor to a point from which the received radiation was scattered, reflected, or emitted by the harvested crop within the interior of the open-top crop container based on the sensing signal;
• and
• outputs the fill-state of the harvested crop within the interior of the open-top crop container based on the propagation distance.