Abstract: In this paper, we address the problem of automatically creating a meaningful spatial representation of 3D virtual environments, suitable for spatial reasoning. We propose a spatial analysis technique that distinguishes indoor, outdoor and covered parts of the environment. It also separates buildings into floors linked by stairs and represent floors as rooms linked by doorsteps. On this basis, we compute a natural hierarchical representation of the environment. We also demonstrate that this representation can be used to handle multi-criterion queries relating to spatial reasoning including zone selection and path planning.