In this paper

after an analysis and comparison of data structure between MapInfo and AutoCAD

first a method for distilling elevation points

elevation values and other correlative information from graphical symbols and labels in CAD by matching area and transforming types is put forward. Second a means is designed to create building polygons by the way of recurring topological relations between points and lines

on the basis of lines that represent buildings in CAD. Finally

automatically acquiring spatial and attributive features of terrain elevation and buildings is implemented. Making use of these processed data

an urban DEM model and a display usage of 3D images are constructed. Getting cross the procedure of data processing in which data transform from CAD format to GIS vector data then GIS raster data and 3D images

an integrated processing method of 3D urban modeling is formed. The method adopted in this paper is more simple and faster than the ways and means of engineering air photogrammetry

and it has a more practical value. Here

an example based on the terrain data of the 32th Jiefang in Suzhou is given by using the integrated method of 3D urban modeling and a fairy good result is attained.