A method for describing plant architecture which integrates topology and geometry

This paper presents a method for describing plant architecture using topological and geometric information. This method is based on the use of a multiscale model of plant topology - called multiscale tree graphs - which is extended to include geometry. The relationships between both multiscale topology and geometry are explicitly identified and topology and geometry are shown to contain redundant information. This redundancy is expressed as sets of constraints between the geometrical parameters of plant components that belong either to one scale or to different scales. These withinand between-scale constraints are used to reduce the number of measurements when digitizing plant architecture and to implement the geometrical parameters that are not specified. Different solutions for simplifying plant architectural descriptions are proposed. The method, implemented in software dedicated to plant architecture analysis (AMAPmod), does not depend on the plant species or on the geometric model used to describe the plant components. The multiscale approach allows plant architecture to be represented at different levels of accuracy. This method is illustrated on two plants, a 3-year-old apple tree and a 20-year-old walnut tree, which correspond to applications of different sizes and with different goals for the representation. (Résumé d'auteur