1. A device for detecting a plant, comprising: a provider for providing at least one two-dimensional image of a plant leaf with a first two-dimensional resolution, and for providing at least one three-dimensional image of the plant leaf, the three-dimensional image comprising a two-dimensional representation of the plant leaf with a second two-dimensional resolution which is smaller than the first two-dimensional resolution, and comprising a third dimension of the three-dimensional image for points of the two-dimensional representation; and a processor for merging the two-dimensional image and the three-dimensional image so as to acquire a three-dimensional result representation of at least a portion of the plant leaf, said result representation comprising three-dimensional information for a number of points which is larger than the number of points of the portion of the three-dimensional image for which the information about the third dimension exists, to transform the three-dimensional image to a surface representation, to transform the two-dimensional image to a multi-valued three-dimensional representation wherein a third dimension is multi-valued and is restricted to having comprising points on a beam starting from a projection center, and to determine an unambiguous third dimension by calculating an intersection point of the beam with the surface representation.