Digital tree mapping for precision spraying
Precision agriculture tools were specifically developed by the PRECI SPRAY project partners to be able to reduce the amount of pesticides applied to orchard trees. By matching the volume and direction of the spray to the tree foliage shape and volume, pest control materials could be saved. Moreover, the promise for both economic and environmental benefits could be realised. The introduction of information technologies to orchard management led to the development of a high-precision system for sprayers. To define the amount of pesticides that match each tree's needs, the locations and shapes of all trees in the orchard need to be mapped accurately in three dimensions. The sprayer automatically controls the direction and volume of spraying on the basis of all the information collected. More specifically, the sprayer nozzles can open or close and their distance from the target vary, while moving between rows of trees. Tree-mapping and guidance data, for this purpose, are obtained from stereoscopic aerial surveys over the plantation by applying automated image processing and photogrammetry techniques. Aerial triangulation is used to determine accurate space and ground coordinates of any premarked point. These values provide the information needed to reference individual photogrammetric stereo models to data obtained earlier in the growing year and compile tree shape and volume maps. These updated maps, combined with additional management data are passed to the sprayer as a work plan. The spraying vehicle finds its location in real time by means of satellite navigation systems. During the development and testing of this high-precision spraying system, valuable insight was gained in the positive contribution of technical solutions to tree health and protection of the environment.