Developing such multi-agent systems has to deal with multiple scales and multiple viewpoints. The organization of multi-agent simulations must be considered as an evolving interaction among agents of various granularity, which proceed at different time and space scales, and give birth, due to their collective activity, to new types of agents, coexisting within the same simulation. In this approach, the change of scales from a microscopic to a macroscopic level lies, to a certain extent, in the regrouping of agents. The user providing the system with additional information, such as a map of the vegetation, or the soil nature, the topography, etc. Idea outsketched by figure bellow.
Current development focuses on runoff dynamics on a topographic surface under rainfall.
Spatial densities of waterballs locally induce various water depths. At each time step, given simple rules, particles move on the surface downslope according to water depth and topography elevation gradients, their velocities updated accordingly. Visualisation output of waterballs motions on a 3D topographic surface. January 15th-17th 1996.