Building modeling for 3D city model

New development in urban planning, cityscape, real estate management and the like, calls for new demands for 3D city model. There are so many objects in 3D city model such as building,river,road,and so on. The building model is very important in 3D city model. In recent years,a lot of research work about visualization has been done. In our opinions, visualization is only a part of 3D city model, while interactive operation about buildings is rather important as well. In order to implement interactive operation (create ,edit, query, etc. ) . good data structure and model must he develoned.