Fork-lift truck and method for operating a fork-lift truck

The disclosure relates to a fork-lift truck comprising a load carrier, a first optical detector having a first field of view, at least one optical analysing unit arranged to receive and to analyse information from the first optical detector, a second optical detector having a second field of view, wherein the at least one optical analysing unit is arranged to receive and to analyse information from the second optical detector, wherein the first and second optical detector are movable together with the load carrier, wherein the first optical detector is positioned at a first position in relation to the load carrier, such that the first field of view, if the load carrier is empty, includes at least a part of the load carrier and an extension of the load carrier so one or more potential objects positioned within a predetermined distance from the load carrier in the direction of the extension of the load carrier can be detected, wherein the second optical detector is positioned at a second position, such that the second field of view includes, if the load carrier is loaded, a predetermined volume above the load so that potential objects positioned within the predetermined volume can be detected, and wherein the position and orientation of the second detector is calibrated in relation to a predetermined position on the fork-lift truck, preferably a position on the load carrier, such that, in case one or more objects are positioned in the predetermined volume, at least one three-dimensional relative position can be determined by the at least one optical analysing unit between, on one side, the load and/or load carrier, and, on the other side, the one or more objects positioned in the predetermined volume. The disclosure also relates to a method for operating a fork-lift truck and to a computer program product.