We present a new technique for the fully automated 3D modelling of indoor environments from a point cloud. The point cloud is acquired with several scans and is afterwards processed in order to segment planar structures, which have a noticeable architectural meaning (floor, ceiling and walls) in the interior. The basic approach to data segmentation is plane sweeping based on a hypothesis-and-test strategy. From the segmentation results, the ground plan is created through cell decomposition by trimming the two-dimensional ground space using half-space primitives. An extension in height of the ground contours makes the generation of the 3D model possible. The so-reconstructed indoor model is saved in CAD format for analysis and further applications or, simply, as a record of the interior geometry.