Most classic ecophysiological models rely on crude representations of canopies as stacks of vegetation layers. Therefore, their use in complex canopies implies complicated adaptations as well as simplifying assumptions that are difficult to validate. Alternatively, the ARCHIMED simulation platform uses 3D virtual stands as a support for numerical simulations of biophysical processes such as leaf irradiation, transpiration and temperature and ultimately carbon assimilation. By doing so, detailed information can be integrated from the individual leaf scale up to the individual plant scale, even within complex stands such as agroforestry systems. Simple numerical methods are used for solving multiple feedbacks between light, energy, water and CO2 transfers at leaf, plant and plot scales. Numerical calculations applied at different scales allow simple implementation of complex models involving intricate processes.