The present invention relates to a setup (100) for constructing a weed map. The setup (100) comprises an image recording unit (110; 110') having a video camera (112) and a relief-tracking laser camera (114), an image process- ing and evaluating unit (120), a data storage unit (130) connected to the latter, as well as a weed database (135). The setup (100) also comprises a light source (160), a position detection unit (150) equipped with a location finding element (152) and a location refining element (154) for determining the spatial coordi¬ nates supplied by the former more accurately. The image recording unit (110; 110'), the position detection unit (150) and the light source (160) are all in data communication connection with the image processing and evaluating unit (120). Furthermore, the image processing and evaluating unit (120) is provided with one or more controlling outputs (122, 124), wherein one of the outputs (124) is capable of establishing a data communication connection with the control unit (190) of a separate weeding apparatus.