In combination with the rapid technical improvements of computers, building large virtual scenes has become a popular field in computer graphics for education, films or games. Often, virtual humans populate scenes such as real reconstructed city, disappeared building or virtual town, and they are expected to provide a real life feeling. The specific aim of this thesis is to perform action planning in order to populate these scenes with virtual humans. To achieve this goal, we use a database dedicated to urban life simulation called an Informed Environment. This report presents a design methodology and associated tools for animation purposes in large scale scenes. We propose a space decomposition of the scene into a set of entities allowing automatic path computing regardless of scene size. In order to achieve human behavioural simulation, we decide to focus on the definition of scene decomposition resulting in the creation of a database. The first stage of this work consisted of building a database simulating "urban knowledge" (knowledge about location and associated functionalities) and virtual perceptions (contact with the ground, object perception etc.). These virtual perceptions, necessary for autonomy simulation, but highly costly in time processor consuming, are simulated through database access corresponding to our Informed Environment. We decided to define an ideal 3D model as a test-bed for concepts and tools, integrating both geometrical and semantical data. We also define rules for the design, storage and display options. The "urban knowledge" attached to a simulation is the base of a generic hierarchical model of space decomposition. This model of space decomposition of the 3D scene is related to a specific type of simulation and directly applied to the modelling of the tridimensional scene. Once the database is created, some tools access the database content for path/action computation, knowledge concerning a place, display optimization, places and objects. As 3D data visibility and verification with associated semantic information are difficult to observe, we have defined some tools for database visualisation, verification and modification (the "applicity" software). These tools have been developed in order to offer assistance to the user during manipulation of three-dimensional data. This system is applied to real reconstructed scenes in the framework of the European project CROSSES, for panic simulation during accident. Our field of research has also been extended to the domain of disability help in order to compute path for people with reduced mobility. Our goal was to define some tools and a few constraint methodology that automatically generate all information needed for simulating autonomous behaviour in an urban environment.