The automatic reconstruction of 3D buildings has been an important research topic during the last years.In this paper,a novel method is proposed to automatically reconstruct the 3D building models from segmented data based on pre-defined formal grammar and rules.Such segmented data can be extracted e.g.from terrestrial or mobile laser scanning devices.Two steps are considered in detail.The first step is to transform the segmented data into 3D shapes,for instance using the DXF (Drawing Exchange Format) format which is a CAD data file format used for data interchange between AutoCAD and other program.Second,we develop a formal grammar to describe the building model structure and integrate the pre-defined grammars into the reconstruction process.Depending on the different segmented data,the selected grammar and rules are applied to drive the reconstruction process in an automatic manner.Compared with other existing approaches,our proposed method allows the model reconstruction directly from 3D shapes and takes the whole building into account.